PCV680, PCV680LE, PCV740, PCV740LE
Service Manual
KohlerEngines.com24 690 31 Rev. H 1
2 Safety
3 Maintenance
5 Specifi cations
13 Tools and Aids
16 Troubleshooting
21 Air Cleaner/Intake
22 Propane Electronic Fuel Injection (EFI) System
52 Lubrication System
54 Electrical System
59 Starter System
63 Disassembly/Inspection and Service
81 Reassembly
IMPORTANT: Read all safety precautions and instructions carefully before operating equipment. Refer to operating
instruction of equipment that this engine powers.
Ensure engine is stopped and level before performing any maintenance or service.
Safety
2 24 690 31 Rev. HKohlerEngines.com
SAFETY PRECAUTIONS
WARNING: A hazard that could result in death, serious injury, or substantial property damage.
CAUTION: A hazard that could result in minor personal injury or property damage.
NOTE: is used to notify people of important installation, operation, or maintenance information.
WARNING
Explosive Fuel can
cause fi res and severe
burns.
If a gaseous odor is
detected, ventilate
area and contact an
authorized service
technician.
Propane is extremely fl ammable
and is heavier than air and tends
to settle in low areas where a
spark or fl ame could ignite gas.
Do not start or operate this engine
in a poorly ventilated area where
leaking gas could accumulate and
endanger safety of persons in
area.
To ensure personal safety,
installation and repair of propane
fuel supply systems must be
performed only by qualifi ed
propane system technicians.
Improperly installed and
maintained propane equipment
could cause fuel supply system or
other components to malfunction,
causing gas leaks.
Observe federal, state and local
laws governing propane fuel,
storage, and systems.
WARNING
Rotating Parts can cause
severe injury.
Stay away while engine
is in operation.
Keep hands, feet, hair, and
clothing away from all moving
parts to prevent injury. Never
operate engine with covers,
shrouds, or guards removed.
CAUTION
Failure to utilize or
reassemble debris
screen as designed could
result in debris screen
failure and serious
personal injury.
WARNING
Carbon Monoxide can
cause severe nausea,
fainting or death.
Take precautions
against exposure to
carbon monoxide
(CO)
emissions. Only operate
an engine in well
ventilated areas.
Engine exhaust gases contain
poisonous carbon monoxide.
Carbon monoxide is odorless,
colorless, and can cause death if
inhaled.
WARNING
Accidental Starts can
cause severe injury or
death.
Disconnect and ground
spark plug lead(s) before
servicing.
Before working on engine or
equipment, disable engine as
follows: 1) Disconnect spark plug
lead(s). 2) Disconnect negative (–)
battery cable from battery.
WARNING
Hot Parts can cause
severe burns.
Do not touch engine
while operating or just
after stopping.
Never operate engine with heat
shields or guards removed.
WARNING
Cleaning Solvents can
cause severe injury or
death.
Use only in well
ventilated areas away
from ignition sources.
Carburetor cleaners and solvents
are extremely fl ammable. Follow
cleaner manufacturer’s warnings
and instructions on its proper and
safe use. Never use gasoline as a
cleaning agent.
CAUTION
Electrical Shock can
cause injury.
Do not touch wires while
engine is running.
CAUTION
Damaging Crankshaft
and Flywheel can cause
personal injury.
Using improper procedures can
lead to broken fragments. Broken
fragments could be thrown from
engine. Always observe and use
precautions and procedures when
installing fl ywheel.
WARNING
High Pressure Fluids can
puncture skin and cause
severe injury or death.
Do not work on fuel
system without proper
training or safety
equipment.
Fluid puncture injuries are highly
toxic and hazardous. If an injury
occurs, seek immediate medical
attention.
Maintenance
324 690 31 Rev. H KohlerEngines.com
MAINTENANCE INSTRUCTIONS
WARNING
Before working on engine or equipment, disable engine as
follows: 1) Disconnect spark plug lead(s). 2) Disconnect
negative (–) battery cable from battery.
Accidental Starts can cause severe injury or
death.
Disconnect and ground spark plug lead(s)
before servicing.
Normal maintenance, replacement or repair of emission control devices and systems may be performed by any repair
establishment or individual; however, warranty repairs must be performed by a Kohler authorized dealer.
MAINTENANCE SCHEDULE
Every 25 Hours
1
● Service/replace low-profi le precleaner (if equipped). Air Cleaner/Intake
Every 100 Hours¹
● Check oil cooler fi ns, clean as necessary (if equipped). Air Cleaner/Intake
● Change oil. Lubrication System
● Replace low-profi le air cleaner element (if equipped). Air Cleaner/Intake
● Remove cooling shrouds and clean cooling areas. Air Cleaner/Intake
Every 150 Hours¹
● Check heavy-duty fi lter minder. Air Cleaner/Intake
● Inspect heavy-duty air fi lter paper element and inlet screen area. Air Cleaner/Intake
Every 200 Hours
● Change oil fi lter. Lubrication System
● Replace unique EFI fuel fi lters.
Every 300 Hours¹
● Replace heavy-duty air cleaner element and check inner element. Air Cleaner/Intake
Every 300 Hours³ (Not available for PCV680LE, PCV740LE engine models)
● Change oil and fi lter (KOHLER PRO 10W-50 oil and KOHLER PRO fi lter only). Lubrication System
Every 500 Hours or Annually¹
● Check all lines (high pressure/vacuum) including fi ttings for leaks. Fuel System
● Drain vaporizer/regulator of accumulated fuel deposits. Fuel System
● Replace spark plugs and set gap. Electrical System
Every 500 Hours or Annually
1,2
● Inspect lock-off assembly for damage/leakage. Fuel System
Every 600 Hours or Annually
1
● Replace heavy-duty air cleaner inner element. Air Cleaner/Intake
Every 1500 Hours
1,2
● Have vaporizer/regulator tested. Fuel System
1
Perform these procedures more frequently under severe, dusty, dirty conditions.
2
Must be performed by a Kohler authorized dealer or qualifi ed propane personnel only.
³ Option only if using KOHLER
®
PRO oil and PRO oil fi lter.
REPAIRS/SERVICE PARTS
Kohler genuine service parts can be purchased from Kohler authorized dealers. To fi nd a local Kohler authorized
dealer visit KohlerEngines.com or call 1-800-544-2444 (U.S. and Canada).
Maintenance
4 24 690 31 Rev. HKohlerEngines.com
OIL RECOMMENDATIONS
PCV680, PCV740
All-season KOHLER
®
PRO 10W-50 Synthetic Oil is the
ideal oil for KOHLER engines. It is specifi cally formulated
to extend the oil and oil fi lter change interval to 300
Hours when paired with a KOHLER PRO Extended Life
Oil Filter.
300-Hour oil and oil fi lter change intervals are exclusive
to and only authorized on KOHLER engines that utilize
both the KOHLER PRO 10W-50 Synthetic Oil and
KOHLER PRO Extended Life Oil Filter. Alternative
engine oils and oil fi lters may be used with KOHLER
engines but require 100-Hour oil and 200-Hour oil fi lter
change intervals for proper maintenance. Oil must be
API (American Petroleum Institute) service class SJ or
higher. Select viscosity based on air temperature at time
of operation as shown below.
°F
-20
020324060
50 80 100
°C
-30 -20
-10 0
10 20 30
40
5W-30
10W-30
SAE 30
Kohler PRO 10W-50
PCV680LE, PCV740LE
Only use Full Synthetic ILSAC (International Lubricants
Standardization and Approval Committee) GF-5 or
higher motor oils and API (American Petroleum Institute)
service class SN or higher to meet emissions life of
this engine and protect catalyst muffler. Select viscosity
based on air temperature at time of operation as shown
in table below.
FUEL RECOMMENDATIONS
WARNING
Explosive Fuel can cause fi res and severe
burns.
If a gaseous odor is detected, ventilate area
and contact an authorized service technician.
Propane is extremely fl ammable and is heavier than
air and tends to settle in low areas where a spark or
fl ame could ignite gas. Do not start or operate this
engine in a poorly ventilated area where leaking gas
could accumulate and endanger safety of persons in
area.
To ensure personal safety, installation and repair of
propane fuel supply systems must be performed only
by qualifi ed propane system technicians. Improperly
installed and maintained propane equipment could
cause fuel supply system or other components to
malfunction, causing gas leaks.
Observe federal, state and local laws governing
propane fuel, storage, and systems.
This engine is certifi ed to operate on commercial
propane with a minimum propane content of 85% (per
GPA STD 2140). If you have any questions, contact your
propane supplier.
This engine requires propane fuel in a
gaseous/vapor
source from a supply tank designed for use with
gaseous/vapor draw.
Propane from an appropriate propane fuel tank (supplied
separately) is required to operate this engine.
STORAGE
If engine will be out of service for 2 months or more
follow procedure below.
1. Change oil while engine is still warm from operation
(NOT required if using KOHLER PRO 10W-50
full-synthetic oil). Remove spark plug(s) and pour
about 1 oz. of engine oil into cylinder(s). Replace
spark plug(s) and crank engine slowly to distribute
oil.
2. Disconnect negative (-) battery cable.
3. Separate propane tank from unit and store
separately in an area designated for safe propane
tank storage.
4. Store engine in a clean, dry place.
Specifi cations
524 690 31 Rev. H KohlerEngines.com
Dimensions in millimeters.
Inch equivalents shown in [ ].
412.98
[16.259]
296.38
[11.668]
269.48
[10.609]
96.02
[3.780]
135.00
[5.315]
AIR FILTER RAIN CAP
REMOVAL
130.00
[5.118]
AIR FILTER
COVER ASSEMBLY
REMOVAL
73.06
[2.877]
SPARK PLUG REMOVAL
52.36 [2.061]
SPARK PLUG
BOOT REMOVAL
22.84 [0.899]
SPARK PLUG BOOT
246.07
[9.688]
SPARK
PLUG
BOOT
REMOVAL
253.53
[9.982]
SPARK
PLUG
REMOVAL
417.98 [16.456]
SAFETY AIR FILTER
ELEMENT REMOVAL
530.30 [20.878]
PRIMARY AIR FILTER
ELEMENT REMOVAL
OIL FILL & DIPSTICK
MOUNTING
HOLE “A”
ENGINE
495.66
[19.514]
ENGINE
152.99
[6.023]
45.35
[1.786]
137.09
[5.397]
15.70
[0.618]
OIL FILTER
REMOVAL
81.86
[3.223]
73.23 [2.883]
SPARK PLUG REMOVAL
52.45
[2.065]
SPARK PLUG
BOOT REMOVAL
27.43
[1.080]
SPARK PLUG
BOOT
246.28
[9.696]
SPARK
PLUG
BOOT
REMOVAL
253.53
[9.982]
SPARK
PLUG
REMOVAL
20˚
20˚
FLYWHEEL SIDE
154.08
[6.066]
92.08
[3.625]
EXHAUST
PORT #1
72.08
[2.838]
EXHAUST
PORT #2
STARTER SIDE
367.38
[14.464]
13.38
[0.527]
40.80
[1.606]
ENGINE MOUNTING
SURFACE
OIL DRAIN PLUG
3/8 N.P.T INCH
405.85
[15.978]
247.85
[9.758]
445.32
[17.532]
OIL COOLER
REGULATOR RECTIFIER
REGULATOR ASSEMBLY
143.17
[5.636]
134.45
[5.293]
50.78
[1.999]
13.72
[0.540]
11.81
[0.465]
26.80
[1.055]
86.30
[3.398]
24.895 ± 0.10 [0.980 ± 0.0039]
Ø 28.56 ± 0.01 [1.125 ± 0.005]
OXYGEN
SENSOR
SPARK
PLUG
ENGINE MOUNTING
SURFACE
OIL FILTER SIDE
7/16-20 UNF 2B IN
97.2
[3.827]
38.1 +0.00 -3.81
[1.500 +0.00 -0.150]
ENGINE MOUNTING SURFACE
PTO END
334.4
[13.164]
94.26
[3.711]
15˚
MOUNTING
HOLE “D”
152.25
[5.994]
104.03
[4.096]
89.80
[3.536]
MOUNTING
HOLE “A”
MOUNTING
HOLE “B”
MOUNTING
HOLE “C”
242.22
[9.536]
48.39
[1.905]
50
[1.969]
EXHAUST
PORT #2
SOLENOID
SHIFT STARTER
45˚ ± 0.135˚
45˚ ± 0.135˚
35˚ ± 0.135˚
35˚ ± 0.135˚
72.84 ± 0.30
[2.868 ± 0.118]
15˚
4X Ø 8.64.7.54 [0.340/0.297 THRU
Ø 254.00 ± 0.3 [10.000] B.C.
2X 89.80
[3.536]
50
[1.969]
EXHAUST
PORT #2
Engine Dimensions
Specifi cations
6 24 690 31 Rev. HKohlerEngines.com
ENGINE IDENTIFICATION NUMBERS
Kohler engine identifi cation numbers (model, specifi cation and serial) should be referenced for effi cient repair,
ordering correct parts, and engine replacement.
Model . . . . . . . . . . . . . . . . . . . . . PCV680
Propane EFI Command Engine
Vertical Shaft
Numerical Designation
Specifi cation . . . . . . . . . . . . . . . PCV680-3001
Serial . . . . . . . . . . . . . . . . . . . . . 4923500328
Year Manufactured Code Factory Code
Code Year
49 2019
50 2020
51 2021
GENERAL SPECIFICATIONS
4,7
PCV680, PCV680LE, PCV740, PCV740LE
Bore 83 mm (3.27 in.)
Stroke 69 mm (2.72 in.)
Displacement 747 cc (45.6 cu. in.)
Oil Capacity (refi ll) 1.6-1.9 L (1.7-2.0 U.S. qt.)
Maximum Angle of Operation
(@ full oil level)
5
25°
TORQUE SPECIFICATIONS
4,6
PCV680, PCV680LE, PCV740, PCV740LE
Blower Housing
Into cored aluminum hole or weld nut
M5
M6
Into extruded hole in sheet metal
M5
M6
6.2 N·m (55 in. lb.) into new holes
4.0 N·m (35 in. lb.) into used holes
10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
2.8 N·m (25 in. lb.) into new holes
2.3 N·m (20 in. lb.) into used holes
2.8 N·m (25 in. lb.) into new holes
2.3 N·m (20 in. lb.) into used holes
Connecting Rod
Cap Fastener (torque in increments)
6 mm straight shank
6 mm straight shank gray metallic color
11.6 N·m (103 in. lb.)
13.6 N·m (120 in. lb.)
4
Values are in Metric units. Values in parentheses are English equivalents.
5
Exceeding maximum angle of operation may cause engine damage from insuffi cient lubrication.
6
Lubricate threads with engine oil prior to assembly.
7
Any and all horsepower (hp) references by Kohler are Certifi ed Power Ratings and per SAE J1940 & J1995 hp
standards. Details on Certifi ed Power Ratings can be found at KohlerEngines.com.
Specifi cations
724 690 31 Rev. H KohlerEngines.com
TORQUE SPECIFICATIONS
4,6
PCV680, PCV680LE, PCV740, PCV740LE
Crankcase
Breather Cover Fastener 11.3 N·m (100 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Oil Temperature Sensor (into breather cover) 7.3 N·m (65 in. lb.)
Oil Drain Plug 13.6 N·m (10 ft. lb.)
Cylinder Head
Hex Flange Nut (torque in 2 increments) fi rst to 16.9 N·m (150 in. lb.)
fi nally to 33.9 N·m (300 in. lb.)
Rocker Arm Screw
Black Screw (M6x1.0x34)
Silver Screw (M6x1.0x45)
18.1 N·m (160 in. lb.)
13.6 N·m (120 in. lb.)
Fan/Flywheel
Flywheel Retaining Screw 71.6 N·m (52.8 ft. lb.)
Metal Debris Screen Fastener (to fl ywheel) 9.9 N·m (88 in. lb.)
Fuel Vaporizer/Regulator/Lock-Off
Regulator to Bracket Nut 19.8 N·m (175 in. lb.)
Regulator Bracket Mounting Screw 11.9 N·m (105 in. lb.)
Lock-Off Valve Body Nut 6.5 N·m (57 in. lb.)
Lock-Off Valve Body 20 N·m (177 in. lb.)
Fuel Outlet Fitting Mounting Screws 2.9 N·m (26 in. lb.)
Fuel Inlet Fitting 20 N·m (177 in. lb.)
Governor
Lever Nut 7.1 N·m (63 in. lb.)
Ignition
Spark Plug 27 N·m (20 ft. lb.)
Coil Fastener 10.2 N·m (90 in. lb.)
Electronic Control Unit Screw 6.2 N·m (55 in. lb.)
Rectifi er-Regulator Ground Strap/Ground Lead Fastener
(into backing plate)
2.8 N·m (25 in. lb.) into new holes
2.3 N·m (20 in. lb.) into used holes
Rectifi er-Regulator Ground Lead Fastener to Ground
Lug/Backing Plate
5.6 N·m (50 in. lb.) into new holes
4.0 N·m (35 in. lb.) into used holes
Rectifi er-Regulator Fastener 1.4 N·m (12.6 in. lb.)
Crankshaft Position Sensor
Earlier Design Bracket
Crankshaft Position Sensor to Bracket Screw 11.3 N·m (100 in. lb.)
Crankshaft Position Sensor Bracket to Crankcase Screw 8.3 N·m (73 in. lb.)
Crankshaft Position Sensor
Later Design Bracket
Crankshaft Position Sensor to Bracket Screw 6.8 N·m (60 in. lb.)
Crankshaft Position Sensor Bracket to Crankcase Screw 7.3 N·m (65 in. lb.)
4
Values are in Metric units. Values in parentheses are English equivalents.
6
Lubricate threads with engine oil prior to assembly.
Specifi cations
8 24 690 31 Rev. HKohlerEngines.com
TORQUE SPECIFICATIONS
4,6
PCV680, PCV680LE, PCV740, PCV740LE
Intake Manifold
Fastener (torque in 2 increments) fi rst to 7.8 N·m (69 in. lb.)
fi nally to 10.5 N·m (93 in. lb.)
Manifold Absolute Pressure (MAP) Sensor Fastener
(Engines with Separate MAP and Intake Air Temperature
Sensors)
7.3 N·m (65 in. lb.)
Temperature/Manifold Absolute Pressure (TMAP) Sensor
Fastener (Engines with Combined Sensor)
7.3 N·m (65 in. lb.)
Air Cleaner to Throttle Body Fastener Nut 8.2 N·m (73 in. lb.)
Air Cleaner Mounting Bracket Fastener 5.8 N·m (51 in. lb.)
Fuel Injector Cap Fastener 7.3 N·m (65 in. lb.)
Muffl er
Retaining Nut 27.8 N·m (246 in. lb.)
Oxygen Sensor 50.1 N·m (37 ft . lb.)
Main Support Bracket to Muffl er Fastener (into weld nut)
PCV680LE & PCV740LE engines 9.9 N·m (88 in. lb.)
Oil Cooler
Oil Cooler/Adapter Nipple 28.5 N·m (21 ft . lb.)
Fastener
Into Blower Housing
Between Oil Cooler Hoses
2.8 N·m (25 in. lb.)
2.3 N·m (20 in. lb.)
Oil Pan
Fastener 25.6 N·m (227 in. lb.)
Speed Control Bracket
Fastener assembled to cylinder heads 10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Fastener assembled to blower housing 2.8 N·m (25 in. lb.) into new holes
2.3 N·m (20 in. lb.) into used holes
Starter Assembly
Thru Bolt 5.6-9.0 N·m (49-79 in. lb.)
Mounting Screw 16.0 N·m (142 in. lb.)
Brush Holder Mounting Screw 2.5-3.3 N·m (22-29 in. lb.)
Starter Solenoid
Mounting Hardware 4.0-6.0 N·m (35-53 in. lb.)
Nut, Positive (+) Brush Lead 8.0-11.0 N·m (71-97 in. lb.)
Stator
Mounting Screw 6.2 N·m (55 in. lb.) into new holes
4.0 N·m (35 in. lb.) into used holes
Valve Cover
Fastener 9.0 N·m (80 in. lb.)
4
Values are in Metric units. Values in parentheses are English equivalents.
6
Lubricate threads with engine oil prior to assembly.
Specifi cations
924 690 31 Rev. H KohlerEngines.com
CLEARANCE
SPECIFICATIONS
4
PCV680, PCV680LE, PCV740, PCV740LE
Camshaft
End Play (with shim) 0.101/0.406 mm (0.0040/0.0160 in.)
Running Clearance 0.025/0.105 mm (0.001/0.004 in.)
Bore I.D.
New
Max. Wear Limit
20.000/20.025 mm (0.7874/0.7884 in.)
20.038 mm (0.7889 in.)
Bearing Surface O.D.
New
Max. Wear Limit
19.920/19.975 mm (0.7843/0.7864 in.)
19.914 mm (0.7840 in.)
Connecting Rod
Connecting Rod-to-Crankpin
Running Clearance @ 21°C
(70°F)
New
Max. Wear Limit
0.043/0.073 mm (0.0017/0.0029 in.)
0.088 mm (0.0035 in.)
Connecting Rod-to-Crankpin
Side Clearance 0.26/0.63 mm (0.0102/0.0248 in.)
Connecting Rod-to-Piston Pin
Running Clearance @ 21°C
(70°F)
0.015/0.028 mm (0.0006/0.0011 in.)
Piston Pin End I.D. @ 21°C
(70°F)
New
Max. Wear Limit
17.015/17.023 mm (0.6699/0.6702 in.)
17.036 mm (0.6707 in.)
Crankcase
Governor Cross Shaft Bore I.D.
New
Max. Wear Limit
8.025/8.075 mm (0.3159/0.3179 in.)
8.088 mm (0.3184 in.)
Crankshaft
End Play (free) 0.025/0.635 mm (0.001/0.025 in.)
Bore (in crankcase)
New
Max. Wear Limit
40.972/40.997 mm (1.6131/1.6141 in.)
41.011 mm (1.6146 in.)
Bore (in oil pan)
New 40.974/41.000 mm (1.6131/1.6141 in.)
Crankshaft to Sleeve Bearing
(oil pan) Running Clearance
New 0.03/0.12 mm (0.001/0.005 in.)
Crankshaft Bore (oil pan)-to-
Crankshaft Running Clearance
New 0.039/0.087 mm (0.0015/0.0034 in.)
Flywheel End Main Bearing
Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper Limit
Max. Out-of-Round Limit
40.913/40.935 mm (1.6107/1.6116 in.)
40.843 mm (1.608 in.)
0.022 mm (0.0009 in.)
0.025 mm (0.0010 in.)
4
Values are in Metric units. Values in parentheses are English equivalents.
Specifi cations
10 24 690 31 Rev. HKohlerEngines.com
CLEARANCE
SPECIFICATIONS
4
PCV680, PCV680LE, PCV740, PCV740LE
Crankshaft (continued)
Oil Pan End Main Bearing
Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper Limit
Max. Out-of-Round Limit
40.913/40.935 mm (1.6107/1.6116 in.)
40.843 mm (1.608 in.)
0.022 mm (0.0009 in.)
0.025 mm (0.0010 in.)
Connecting Rod Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper Limit
Max. Out-of-Round Limit
35.950/35.973 mm (1.4153/1.4163 in.)
35.941 mm (1.415 in.)
0.018 mm (0.0007 in.)
0.025 mm (0.0010 in.)
Crankshaft T.I.R.
PTO End, Crank in Engine
Entire Crank, in V-Blocks
0.279 mm (0.0110 in.)
0.10 mm (0.0039 in.)
Cylinder Bore
Bore I.D.
New 83.006/83.031 mm (3.2680/3.2689 in.)
O.D. - Max. Wear Limit 83.081 mm (3.2709 in.)
Max. Out-of-Round Limit 0.120 mm (0.0047 in.)
Max. Taper 0.05 mm (0.0020 in.)
Cylinder Head
Max. Out-of-Flatness 0.076 mm (0.003 in.)
Governor
Governor Cross Shaft -to-
Crankcase Running Clearance
0.025/0.126 mm (0.0009/0.0049 in.)
Cross Shaft O.D.
New
Max. Wear Limit
7.949/8.000 mm (0.3129/0.3149 in.)
7.936 mm (0.3124 in.)
Governor Gear Shaft -to-
Governor Gear Running
Clearance
0.090/0.160 mm (0.0035/0.0063 in.)
Gear Shaft O.D.
New
Max. Wear Limit
5.990/6.000 mm (0.2358/0.2362 in.)
5.977 mm (0.2353 in.)
Ignition
Spark Plug Gap 0.76 mm (0.030 in.)
Crankshaft Position Sensor Air
Gap (only on earlier design
sensor bracket)
0.2-0.7 mm (0.008-0.027 in.)
Crankshaft Position Sensor
Max. Air Gap (only on later
design sensor bracket)
2.794 mm (0.110 in.)
4
Values are in Metric units. Values in parentheses are English equivalents.
Specifi cations
1124 690 31 Rev. H KohlerEngines.com
CLEARANCE
SPECIFICATIONS
4
PCV680, PCV680LE, PCV740, PCV740LE
Piston, Piston Rings, and Piston Pin
Piston-to-Piston Pin Running
Clearance
0.006/0.017 mm (0.0002/0.0007 in.)
Pin Bore I.D.
New
Max. Wear Limit
17.006/17.012 mm (0.6695/0.6698 in.)
17.025 mm (0.6703 in.)
Pin O.D.
New
Max. Wear Limit
16.995/17.000 mm (0.6691/0.6693 in.)
16.994 mm (0.6691 in.)
Top Compression Ring-to-
Groove Side Clearance
0.030/0.070 mm (0.001/0.0026 in.)
Middle Compression Ring-to-
Groove Side Clearance
0.030/0.070 mm (0.001/0.0026 in.)
Oil Control Ring-to-Groove Side
Clearance
0.060/0.190 mm (0.0022/0.0073 in.)
Top Compression Ring End Gap
New Bore 0.189/0.277 mm (0.0074/0.0109 in.)
Used Bore (Max.) 0.531 mm (0.0209 in.)
Center Compression Ring End
Gap
New Bore 1.519/1.797 mm (0.0598/0.0708 in.)
Used Bore (Max.) 2.051 mm (0.0808 in.)
Thrust Face O.D.
8
82.978 mm (3.2668 in.)
Max. Wear Limit 82.833 mm (3.2611 in.)
Piston Thrust Face-to Cylinder
Bore
8
Running Clearance
New 0.019/0.062 mm (0.0007/0.0024 in.)
Valves and Valve Lifters
Hydraulic Lifter to Crankcase
Running Clearance
0.011/0.048 mm (0.0004/0.0019 in.)
Intake Valve Stem-to-Valve
Guide Running Clearance
0.040/0.078 mm (0.0016/0.0031 in.)
Exhaust Valve Stem-to-Valve
Guide Running Clearance
0.052/0.090 mm (0.0020/0.0035 in.)
Intake Valve Guide I.D.
New
Max. Wear Limit
7.040/7.060 mm (0.2772/0.2780 in.)
7.134 mm (0.2809 in.)
Exhaust Valve Guide I.D.
New
Max. Wear Limit
7.040/7.060 mm (0.2772/0.2780 in.)
7.159 mm (0.2819 in.)
Valve Guide Reamer Size
Standard
0.25 mm O.S.
7.050 mm (0.2776 in.)
7.300 mm (0.2874 in.)
Intake Valve Minimum Lift 8.07 mm (0.3177 in.)
Exhaust Valve Minimum Lift 8.07 mm (0.3177 in.)
Nominal Valve Seat Angle 45°
4
Values are in Metric units. Values in parentheses are English equivalents.
8
Measure 6 mm (0.236 in.) above bottom of piston skirt at right angles to piston pin.
Specifi cations
12 24 690 31 Rev. HKohlerEngines.com
GENERAL TORQUE VALUES
Metric Fastener Torque Recommendations for Standard Applications
Property Class
Noncritical
Fasteners
Into Aluminum
Size
4.8
5.8
8.8
10.9 12.9
Tightening Torque: N·m (in. lb.) ± 10%
M4 1.2 (11) 1.7 (15) 2.9 (26) 4.1 (36) 5.0 (44) 2.0 (18)
M5 2.5 (22) 3.2 (28) 5.8 (51) 8.1 (72) 9.7 (86) 4.0 (35)
M6 4.3 (38) 5.7 (50) 9.9 (88) 14.0 (124) 16.5 (146) 6.8 (60)
M8 10.5 (93) 13.6 (120) 24.4 (216) 33.9 (300) 40.7 (360) 17.0 (150)
Tightening Torque: N·m (ft. lb.) ± 10%
M10 21.7 (16) 27.1 (20) 47.5 (35) 66.4 (49) 81.4 (60) 33.9 (25)
M12 36.6 (27) 47.5 (35) 82.7 (61) 116.6 (86) 139.7 (103) 61.0 (45)
M14 58.3 (43) 76.4 (56) 131.5 (97) 184.4 (136) 219.7 (162) 94.9 (70)
Torque Conversions
N·m = in. lb. x 0.113 in. lb. = N·m x 8.85
N·m = ft. lb. x 1.356 ft. lb. = N·m x 0.737
English Fastener Torque Recommendations for Standard Applications
Bolts, Screws, Nuts and Fasteners Assembled Into Cast Iron or Steel
Grade 2 or 5 Fasteners
Into Aluminum
Size Grade 2 Grade 5 Grade 8
Tightening Torque: N·m (in. lb.) ± 20%
8-32 2.3 (20) 2.8 (25) — 2.3 (20)
10-24 3.6 (32) 4.5 (40) — 3.6 (32)
10-32 3.6 (32) 4.5 (40) — —
1/4-20 7.9 (70) 13.0 (115) 18.7 (165) 7.9 (70)
1/4-28 9.6 (85) 15.8 (140) 22.6 (200) —
5/16-18 17.0 (150) 28.3 (250) 39.6 (350) 17.0 (150)
5/16-24 18.7 (165) 30.5 (270) — —
3/8-16 29.4 (260) — — —
3/8-24 33.9 (300) — — —
Tightening Torque: N·m (ft. lb.) ± 20%
5/16-24 — — 40.7 (30) —
3/8-16 — 47.5 (35) 67.8 (50) —
3/8-24 — 54.2 (40) 81.4 (60) —
7/16-14 47.5 (35) 74.6 (55) 108.5 (80) —
7/16-20 61.0 (45) 101.7 (75) 142.5 (105) —
1/2-13 67.8 (50) 108.5 (80) 155.9 (115) —
1/2-20 94.9 (70) 142.4 (105) 223.7 (165) —
9/16-12 101.7 (75) 169.5 (125) 237.3 (175) —
9/16-18 135.6 (100) 223.7 (165) 311.9 (230) —
5/8-11 149.5 (110) 244.1 (180) 352.6 (260) —
5/8-18 189.8 (140) 311.9 (230) 447.5 (330) —
3/4-10 199.3 (147) 332.2 (245) 474.6 (350) —
3/4-16 271.2 (200) 440.7 (325) 637.3 (470) —
Tools and Aids
1324 690 31 Rev. H KohlerEngines.com
Certain quality tools are designed to help you perform specifi c disassembly, repair, and reassembly procedures. By
using these tools, you can properly service engines easier, faster, and safer! In addition, you’ll increase your service
capabilities and customer satisfaction by decreasing engine downtime.
Here is a list of tools and their source.
NOTE: Not all tools listed are required to service this engine.
SEPARATE TOOL SUPPLIERS
Kohler Tools
Contact your local Kohler source of
supply.
SE Tools
415 Howard St.
Lapeer, MI 48446
Phone 810-664-2981
Toll Free 800-664-2981
Fax 810-664-8181
Design Technology Inc.
768 Burr Oak Drive
Westmont, IL 60559
Phone 630-920-1300
Fax 630-920-0011
TOOLS
Description Source/Part No.
Alcohol Content Tester
For testing alcohol content (%) in reformulated/oxygenated fuels.
Kohler 25 455 11-S
Camshaft Endplay Plate
For checking camshaft endplay.
SE Tools KLR-82405
Camshaft Seal Protector (Aegis)
For protecting seal during camshaft installation.
SE Tools KLR-82417
Dual Gauge Cylinder Leakdown Tester
For checking combustion retention and if cylinder, piston, rings, or valves are worn.
Individual component available:
Adapter 12 mm x 14 mm (Required for leakdown test on XT-6 engines)
Kohler 25 761 46-S
Design Technology Inc.
DTI-731-03
Dealer Tool Kit
Complete kit of Kohler required tools.
Components of 25 761 39-S
Ignition System Tester
Dual Gauge Cylinder Leakdown Test Tool
Oil Pressure Test Kit
Digital Vacuum/Pressure Tester
Kohler 25 761 39-S
Kohler 25 455 01-S
Kohler 25 761 46-S
Kohler 25 761 06-S
Kohler 25 455 22-S
Digital Vacuum/Pressure Tester
For checking crankcase vacuum.
Individual component available:
Rubber Adapter Plug
Kohler 25 455 22-S
Design Technology Inc.
DTI-721-10
EFI Service Kit
For troubleshooting and setting up an EFI engine.
Components of 24 761 01-S
Fuel Pressure Tester
Noid Light
90° Adapter
Code Plug, Red Wire
Code Plug, Blue Wire
Code Plug, Yellow Wire
Can Bus Reset Tool, Green Wire
Shrader Valve Adapter Hose
Wire Probe Set (2 pieces regular wire with clip; 1 piece fused wire)
Hose Removal Tool, Dual Size/End (also sold as individual Kohler tool)
K-Line Adapter Jumper Lead Wiring Harness
Kohler 24 761 01-S
Design Technology Inc.
DTI-019
DTI-021
DTI-023
DTI-027
DTI-029
DTI-028
DTI-030
DTI-037
DTI-031
DTI-033
Kohler 25 176 23-S
KOHLER
®
Diagnostic System (KDS) Gen 2
For Laptop or Desktop PC.
Components of 25 761 50-S
Engine Communication Module
7 Pin to DB9 Cable
USB Module to PC Cable
7 Pin to 4 Pin Adapter
Kohler 25 761 50-S
Kohler 25 761 47-S
Kohler 25 761 48-S
Kohler 25 761 49-S
Kohler 25 761 53-S
Mobile KDS (Wireless) Module
For mobile Android or iOS EFI diagnostics.
Individual component available:
Wireless Diagnostic System Interface Cable
Kohler 25 761 45-S
Kohler 25 761 44-S
Tools and Aids
14 24 690 31 Rev. HKohlerEngines.com
TOOLS
Description Source/Part No.
Flywheel Puller
For properly removing fl ywheel from engine.
SE Tools KLR-82408
Flywheel Anchor Bolts, Washers, Nuts Tool
Used with Flywheel Puller for properly removing fl ywheel from 5400 Series engine.
Kohler 25 086 753-S
Hose Removal Tool, Dual Size/End (also available in EFI Service Kit)
Used to properly remove fuel hose from engine components.
Kohler 25 455 20-S
Ignition System Tester
For testing output on all systems, including CD.
Kohler 25 455 01-S
Inductive Tachometer (Digital)
For checking operating speed (RPM) of an engine.
Design Technology Inc.
DTI-110
Oil Pressure Test Kit
For testing/verifying oil pressure on pressure lubricated engines.
Kohler 25 761 06-S
Rectifi er-Regulator Tester (120 volt current)
Rectifi er-Regulator Tester (240 volt current)
For testing rectifi er-regulators.
Components of 25 761 20-S and 25 761 41-S
CS-PRO Regulator Test Harness
Special Regulator Test Harness with Diode
Kohler 25 761 20-S
Kohler 25 761 41-S
Design Technology Inc.
DTI-031R
DTI-033R
Spark Advance Module (SAM) Tester
For testing SAM (ASAM and DSAM) on engines with SMART-SPARK
™
.
Kohler 25 761 40-S
Starter Servicing Kit (All Starters)
For removing and reinstalling drive retaining rings and brushes.
Individual component available:
Starter Brush Holding Tool (Solenoid Shift)
SE Tools KLR-82411
SE Tools KLR-82416
Stepper Motor Controller Tool
For testing operation of stepper motor/Digital Linear Actuator (DLA).
Kohler 25 455 21-S
Jumper Lead Tool
For use with Stepper Motor Controller Tool to test rotary stepper motor.
Kohler 25 518 43-S
Triad/OHC Timing Tool Set
For holding cam gears and crankshaft in timed position while installing timing belt.
Kohler 28 761 01-S
Valve Guide Reamer (K and M Series)
For properly sizing valve guides after installation.
Design Technology Inc.
DTI-K828
Valve Guide Reamer O.S. (Command Series)
For reaming worn valve guides to accept replacement oversize valves. Can be used
in low-speed drill press or with handle below for hand reaming.
Kohler 25 455 12-S
Reamer Handle
For hand reaming using Kohler 25 455 12-S reamer.
Design Technology Inc.
DTI-K830
AIDS
Description Source/Part No.
Camshaft Lubricant (Valspar ZZ613) Kohler 25 357 14-S
Dielectric Grease (GE/Novaguard G661) Kohler 25 357 11-S
Dielectric Grease Loctite
®
51360
Kohler Electric Starter Drive Lubricant (Inertia Drive) Kohler 52 357 01-S
Kohler Electric Starter Drive Lubricant (Solenoid Shift) Kohler 52 357 02-S
RTV Silicone Sealant
Loctite
®
5900
®
Heavy Body in 4 oz. aerosol dispenser.
Only oxime-based, oil resistant RTV sealants, such as those listed, are approved
for use. Permatex
®
the Right Stuff
®
1 Minute Gasket™ or Loctite
®
Nos. 5900
®
or
5910
®
are recommended for best sealing characteristics.
Kohler 25 597 07-S
Loctite
®
5910
®
Loctite
®
Ultra Black 598™
Loctite
®
Ultra Blue 587™
Loctite
®
Ultra Copper 5920™
Permatex
®
the Right Stuff
®
1
Minute Gasket™
Spline Drive Lubricant Kohler 25 357 12-S
Tools and Aids
1524 690 31 Rev. H KohlerEngines.com
FLYWHEEL HOLDING TOOL ROCKER ARM/CRANKSHAFT TOOL
A fl ywheel holding tool can be made out of an old junk
fl ywheel ring gear and used in place of a strap wrench.
1. Using an abrasive cut-off wheel, cut out a six tooth
segment of ring gear as shown.
2. Grind off any burrs or sharp edges.
3. Invert segment and place it between ignition bosses
on crankcase so tool teeth engage fl ywheel ring
gear teeth. Bosses will lock tool and fl ywheel in
position for loosening, tightening, or removing with a
puller.
A spanner wrench to lift rocker arms or turn crankshaft
may be made out of an old junk connecting rod.
1. Find a used connecting rod from a 10 HP or larger
engine. Remove and discard rod cap.
2. Remove studs of a Posi-Lock rod or grind off
aligning steps of a Command rod, so joint surface is
fl at.
3. Find a 1 in. long capscrew with correct thread size to
match threads in connecting rod.
4. Use a fl at washer with correct I.D. to slip on
capscrew and approximately 1 in. O.D. Assemble
capscrew and washer to joint surface of rod.
Troubleshooting
16 24 690 31 Rev. HKohlerEngines.com
Exhaust System PCV680LE, PCV740LE
NOTE: Overfueling can cause overheating of muffl er
and premature failure.
● PCV680LE and PCV740LE engines are designed
with lower emissions with a catalyst in exhaust
system. If run quality, including misfi ring, is in
question, shut engine down and obtain service right
away.
Engine Cranks But Will Not Start
● Battery connected backwards.
● Blown fuse.
● Carburetor solenoid malfunction.
● Choke not closing.
● Clogged fuel line or fuel fi lter.
● Diode in wiring harness failed in open circuit mode.
● DSAI or DSAM malfunction.
● Empty fuel tank.
● Faulty electronic control unit.
● Faulty ignition coil(s).
● Faulty spark plug(s).
● Fuel pump malfunction-vacuum hose clogged or
leaking.
● Fuel shut-off valve closed.
● Ignition module(s) faulty or improperly gapped.
● Insuffi cient voltage to electronic control unit.
● Interlock switch is engaged or faulty.
● Key switch or kill switch in OFF position.
● Low oil level.
● Quality of fuel (dirt, water, stale, mixture).
● SMART-SPARK
TM
malfunction.
● Spark plug lead(s) disconnected.
Engine Starts But Does Not Keep Running
● Faulty carburetor.
● Faulty cylinder head gasket.
● Faulty or misadjusted choke or throttle controls.
● Fuel pump malfunction-vacuum hose clogged or
leaking.
● Intake system leak.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Quality of fuel (dirt, water, stale, mixture).
● Restricted fuel tank cap vent.
TROUBLESHOOTING GUIDE
When troubles occur, be sure to check simple causes which, at fi rst, may seem too obvious to be considered. For
example, a starting problem could be caused by an empty fuel tank.
Some general common causes of EFI engine troubles are listed below and vary by engine specifi cation. Use these to
locate causing factors.
Engine Starts Hard
● Clogged fuel line or fuel fi lter.
● Engine overheated.
● Faulty ACR mechanism.
● Faulty or misadjusted choke or throttle controls.
● Faulty spark plug(s).
● Flywheel key sheared.
● Fuel pump malfunction-vacuum hose clogged or
leaking.
● Interlock switch is engaged or faulty.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Low compression.
● Quality of fuel (dirt, water, stale, mixture).
● Weak spark.
Engine Will Not Crank
● Battery is discharged.
● Faulty electric starter or solenoid.
● Faulty key switch or ignition switch.
● Interlock switch is engaged or faulty.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Pawls not engaging in drive cup.
● Seized internal engine components.
Engine Runs But Misses
● Carburetor adjusted incorrectly.
● Engine overheated.
● Faulty spark plug(s).
● Ignition module(s) faulty or improperly gapped.
● Incorrect crankshaft position sensor air gap.
● Interlock switch is engaged or faulty.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Quality of fuel (dirt, water, stale, mixture).
● Spark plug lead(s) disconnected.
● Spark plug lead boot loose on plug.
● Spark plug lead loose.
Engine Will Not Idle
● Engine overheated.
● Faulty spark plug(s).
● Idle fuel adjusting needle(s) improperly set.
● Idle speed adjusting screw improperly set.
● Inadequate fuel supply.
● Low compression.
● Quality of fuel (dirt, water, stale, mixture).
● Restricted fuel tank cap vent.
1724 690 31 Rev. H KohlerEngines.com
Troubleshooting
Engine Overheats
● Cooling fan broken.
● Excessive engine load.
● Fan belt failed/off .
● Faulty carburetor.
● High crankcase oil level.
● Lean fuel mixture.
● Low cooling system fl uid level.
● Low crankcase oil level.
● Radiator, and/or cooling system components clogged,
restricted, or leaking.
● Water pump belt failed/broken.
● Water pump malfunction.
Engine Knocks
● Excessive engine load.
● Hydraulic lifter malfunction.
● Incorrect oil viscosity/type.
● Internal wear or damage.
● Low crankcase oil level.
● Quality of fuel (dirt, water, stale, mixture).
Engine Loses Power
● Dirty air cleaner element.
● Engine overheated.
● Excessive engine load.
● Restricted exhaust.
● Faulty spark plug(s).
● High crankcase oil level.
● Incorrect governor setting.
● Low battery.
● Low compression.
● Low crankcase oil level.
● Quality of fuel (dirt, water, stale, mixture).
Engine Uses Excessive Amount of Oil
● Loose or improperly torqued fasteners.
● Blown head gasket/overheated.
● Breather reed broken.
● Clogged, broken, or inoperative crankcase breather.
● Crankcase overfi lled.
● Incorrect oil viscosity/type.
● Worn cylinder bore.
● Worn or broken piston rings.
● Worn valve stems/valve guides.
Oil Leaks from Oil Seals, Gaskets
● Breather reed broken.
● Clogged, broken, or inoperative crankcase breather.
● Loose or improperly torqued fasteners.
● Piston blow by, or leaky valves.
● Restricted exhaust.
EXTERNAL ENGINE INSPECTION
NOTE: It is good practice to drain oil at a location away
from workbench. Be sure to allow ample time for
complete drainage.
Before cleaning or disassembling engine, make a
thorough inspection of its external appearance and
condition. This inspection can give clues to what
might be found inside engines (and cause) when it is
disassembled.
● Check for buildup of dirt and debris on crankcase,
cooling fi ns, grass screen, and other external surfaces.
Dirt or debris on these areas can cause overheating.
● Check for obvious fuel and oil leaks, and damaged
components. Excessive oil leakage can indicate a
clogged or inoperative breather, worn or damaged
seals or gaskets, or loose fasteners.
● Check air cleaner cover and base for damage or
indications of improper fi t and seal.
● Check air cleaner element. Look for holes, tears,
cracked or damaged sealing surfaces, or other
damage that could allow unfi ltered air into engine. A
dirty or clogged element could indicate insuffi cient or
improper maintenance.
● Check throttle body throat for dirt. Dirt in throat is
further indication that air cleaner was not functioning
properly.
● Check if oil level is within operating range on dipstick.
If it is above, sniff for gasoline odor.
● Check condition of oil. Drain oil into a container; it
should fl ow freely. Check for metal chips and other
foreign particles.
Sludge is a natural by-product of combustion; a small
accumulation is normal. Excessive sludge formation
could indicate over rich fuel settings, weak ignition,
overextended oil change interval or wrong weight or
type of oil was used.
CLEANING ENGINE
WARNING
Cleaning Solvents can cause severe injury or
death.
Use only in well ventilated areas away from
ignition sources.
Carburetor cleaners and solvents are extremely
fl ammable. Follow cleaner manufacturer’s warnings
and instructions on its proper and safe use. Never use
gasoline as a cleaning agent.
After inspecting external condition of engine, clean
engine thoroughly before disassembly. Clean individual
components as engine is disassembled. Only clean
parts can be accurately inspected and gauged for wear
or damage. There are many commercially available
cleaners that will quickly remove grease, oil, and grime
from engine parts. When such a cleaner is used, follow
manufacturer’s instructions and safety precautions
carefully.
Make sure all traces of cleaner are removed before
engine is reassembled and placed into operation. Even
small amounts of these cleaners can quickly break down
lubricating properties of engine oil.
Troubleshooting
18 24 690 31 Rev. HKohlerEngines.com
Condition Conclusion
Crankcase breather clogged or inoperative. NOTE: If breather is integral part of valve cover and
cannot be serviced separately, replace valve
cover and recheck pressure.
Disassemble breather, clean parts thoroughly, check
sealing surfaces for fl atness, reassemble, and recheck
pressure.
Seals and/or gaskets leaking. Loose or improperly torque
fasteners.
Replace all worn or damaged seals and gaskets. Make
sure all fasteners are tightened securely. Use appropriate
torque valves and sequences when necessary.
Piston blow by or leaky valves (confi rm by inspecting
components).
Recondition piston, rings, cylinder bore, valves and
valves guides.
Restricted exhaust. Check exhaust screen/spark arrestor (if equipped). Clean
or replace as needed. Repair or replace any other
damaged/restricted muffl er or exhaust system parts.
CRANKCASE VACUUM TEST
WARNING
Carbon Monoxide can cause severe nausea,
fainting or death.
Take precautions against exposure to carbon
monoxide
(CO)
emissions. Only operate an
engine in well ventilated areas.
Engine exhaust gases contain poisonous carbon
monoxide. Carbon monoxide is odorless, colorless,
and can cause death if inhaled.
To test crankcase vacuum with manometer:
1. Insert rubber stopper into oil fi ll hole. Be sure pinch
clamp is installed on hose and use tapered adapters
to connect hose between stopper and one
manometer tube. Leave other tube open to
atmosphere. Check that water level in manometer is
at 0 line. Make sure pinch clamp is closed.
2. Start engine and run no-load high speed.
3. Open clamp and note water level in tube.
Level in engine side should be a minimum of 10.2
cm (4 in.) above level in open side.
If level in engine side is less than specifi ed (low/no
vacuum), or level in engine side is lower than level in
open side (pressure), check for conditions in table
below.
4. Close pinch clamp before stopping engine.
To test crankcase vacuum with vacuum/pressure gauge
(inches of water gauge only):
1. Remove dipstick or oil fi ll plug/cap.
2. Install adapter into oil fi ll//dipstick tube opening,
upside down over end of a small diameter dipstick
tube, or directly into engine if a tube is not used.
Insert barbed gauge fi tting into hole in stopper.
3. Run engine and observe gauge reading.
Analog tester–needle movement to left of 0 is a
vacuum, and movement to right indicates a
pressure.
Digital tester–depress test button on top of tester.
Crankcase vacuum should be a minimum of 10.2 cm
(4 in.) of water. If reading is below specifi cation, or if
pressure is present, check table below for possible
causes and conclusions.
WARNING
Rotating Parts can cause severe injury.
Stay away while engine is in operation.
Keep hands, feet, hair, and clothing away from all
moving parts to prevent injury. Never operate engine
with covers, shrouds, or guards removed.
A partial vacuum should be present in crankcase when engine is operating. Pressure in crankcase (normally caused
by a clogged or improperly assembled breather) can cause oil to be forced out at oil seals, gaskets, or other available
spots.
Crankcase vacuum is best measured with either a water manometer or a vacuum gauge (inches of water gauge only).
Complete instructions are provided in kits.
1924 690 31 Rev. H KohlerEngines.com
Troubleshooting
COMPRESSION TEST
A compression test is best performed on a warm engine. Clean any dirt or debris away from base of spark
plug(s) before removing them. Be sure battery is fully charged, unplug ECU, and throttle is wide open during test.
Compression should be at least 160 psi and should not vary more than 15% between cylinders.
Some models may be equipped with an automatic compression release (ACR) mechanism. It is diffi cult to obtain an
accurate compression reading because of ACR mechanism. As an alternative, use cylinder leakdown test described
below.
CYLINDER LEAKDOWN TEST
A cylinder leakdown test can be a valuable alternative to a compression test. By pressurizing combustion chamber
from an external air source you can determine if valves or rings are leaking, and how badly.
Cylinder leakdown tester is a relatively simple, inexpensive leakdown tester for small engines. This tester includes a
quick-connect for attaching adapter hose and a holding tool.
Dual Gauge Test Procedure
1. Run engine until oil temperature reaches and
maintains 150°F (66°C) or more for a minimum of 5
minutes. Ideally, engine should be run under normal
load conditions.
2. Remove spark plug(s) and air fi lter from engine.
3. Rotate crankshaft until piston (of cylinder being
tested) is at top dead center (TDC) of compression
stroke. Hold engine in this position while testing.
Holding tool from kit can be used if PTO end of
crankshaft is accessible. Lock holding tool onto
crankshaft. Install a 3/8 in. breaker bar into hole/slot
of holding tool, so it is perpendicular to both holding
tool and crankshaft PTO.
If fl ywheel end is more accessible, use a breaker bar
and socket on fl ywheel nut/screw to hold it in
position. An assistant may be needed to hold
breaker bar during testing. If engine is mounted in a
piece of equipment, it may be possible to hold it by
clamping or wedging a driven component. Just be
certain engine cannot rotate off TDC in either
direction.
4. Connect an air source (at least 100 PSI) to tool.
5. Turn regulator knob clockwise (increase direction).
Confi rm both gauges read approximately the same
air pressure from 0 to 80 PSI. Note any
discrepancies between gauges for leakage
calculation. Release pressure by turning regulator
knob completely counterclockwise before
proceeding.
6. Install adapter hose into spark plug hole of cylinder
being tested. Use 12 mm x 14 mm adapter if
required.
7. Firmly hold engine at TDC. Connect other end of
adapter hose to tool quick connect. Turn regulator
knob clockwise (increase direction) until left gauge
needle reads 20 PSI.
NOTE: When piston is at TDC, little to no holding force
should be required when air pressure is applied
to cylinder. If excess holding force is required,
this indicates piston is not at TDC. Readjust as
necessary before proceeding.
8. Slowly turn regulator knob clockwise until left hand
gauge maintains selected test pressure (see chart
below).
Left Gauge Regulated Pressure Selection
80 PSI
Recommended for engines over 200 cc
or those exhibiting high leakage at 35 PSI setting.
35 PSI
Recommended for single cylinder
walk-behind push mower applications.
9. Compare right gauge reading to Test Pressure Chart
on next page to identify percentage of leakage. Also
refer to Leakdown Test Results chart on next page
for colors, conditions, and action required.
10. For engines exhibiting leakage in yellow or red zone,
repeat test procedure. Operate engine under normal
load conditions prior to test. Confi rm piston is at TDC
during test.
NOTE: To prevent damage to gauge assembly, always
turn pressure regulator knob to zero
(counterclockwise) after each test.
Troubleshooting
20 24 690 31 Rev. HKohlerEngines.com
Test Pressure Chart for Dual Gauge Tool
Left Gauge Regulated Pressure
Selection Right Gauge Reading in PSI
80 PSI
Recommended for engines over 200
cc or those exhibiting high leakage at
35 PSI setting.
80 72 64 56 48 40 32 24 16 8 0
35 PSI
Recommended for single cylinder
walk-behind push mower
applications.
35 31.5 28 24.5 21 17.5 14 10.5 7 3.5 0
Percentage of leakage 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Green Zone Yellow Zone Red Zone
Leakdown Test Results
Test Result Condition Action
Gauge reading in low
(green) zone.
Piston rings and cylinder in
good condition.
No further action required.
Gauge reading in
moderate (yellow)
zone.
Air escaping from crankcase
breather and/or dipstick tube.
Some wear present causing leakage from
combustion chamber to crankcase. Repair not
required at this time if breather system is
functioning normally.
Air escaping from exhaust. Exhaust valve leakage present, possibly due to
carbon deposits. Repair not required. Carbon
cleaning could be performed to reduce leakage.
Air escaping from intake. Intake valve leakage present, possibly due to
carbon deposits. Repair not required. Carbon
cleaning could be performed to reduce leakage.
Gauge reading in
high (red) zone.
Confi rm consecutive leakdown
test has been performed AFTER
engine has been operated under
normal load conditions.
Air escaping from crankcase
breather and/or dipstick tube.
Excess wear present causing leakage from
combustion chamber to crankcase. Breather
system will not function normally and will fail
crankcase vacuum test if this condition is truly
present. Engine disassembly and analysis
required to determine root cause and
correction.
Air escaping from exhaust. Excess exhaust valve leakage present, possibly
due to carbon deposits and/or valve to seat
sealing issues. Carbon cleaning may reduce
leakage. Valve grind and/or component
replacement may be necessary. Excess oil
consumption and/or excess heat is a suspect
cause and must be resolved to prevent
reoccurrence.
Air escaping from intake. Excess intake valve leakage present, possibly
due to carbon deposits and/or valve to seat
sealing issues. Carbon cleaning may reduce
leakage. Valve grind and/or component
replacement may be necessary. Excess oil
consumption through intake valve and/or
excess heat is a suspect cause and must be
resolved to prevent reoccurrence. Inspect
breather system components and intake valve
stem sealing.
2124 690 31 Rev. H KohlerEngines.com
Air Cleaner/Intake
AIR CLEANER
These systems are CARB/EPA certifi ed and components
should not be altered or modifi ed in any way.
Low-Profi le Air Cleaner Components
B
E
F
H
A
C
D
G
A Air Cleaner Cover B Air Cleaner Knob
C Wing Nut D Element Cover
E Rubber Seal F Precleaner
G Paper Element H Air Cleaner Base
Heavy-Duty Air Cleaner Components
I
J
M
L
K
O
N
P
I Air Cleaner Housing J End Cap
K Element L Inner Element
M Ejector Area N Inlet Screen
O Retaining Clip P Filter Minder
NOTE: Operating engine with loose or damaged air
cleaner components could cause premature
wear and failure. Replace all bent or damaged
components.
NOTE: Paper element cannot be blown out with
compressed air.
Low-Profi le
Loosen knob and remove air cleaner cover.
Precleaner
1. Remove precleaner from paper element.
2. Replace or wash precleaner in warm water with
detergent. Rinse and allow to air dry.
3. Saturate precleaner with new engine oil; squeeze
out excess oil.
4. Reinstall precleaner over paper element.
Paper Element
1. Clean area around element. Remove wing nut,
element cover, and paper element with precleaner.
2. Separate precleaner from element; service
precleaner and replace paper element.
3. Check condition of rubber seal and replace if
necessary.
4. Install new paper element on base; install precleaner
over paper element; reinstall element cover and
secure with wing nut.
Reinstall air cleaner cover and secure with knob.
Heavy-Duty
1. Unhook retaining clips and remove end cap(s).
2. Check and clean inlet screen (if equipped).
3. Pull air cleaner element out of housing and replace.
Check condition of inner element; replace when
dirty.
4. Check all parts for wear, cracks, or damage, and that
ejector area is clean.
5. Install new element(s).
6. Reinstall end cap(s) with dust ejector valve/screen
down; secure with retaining clips.
BREATHER TUBE
Ensure sure both ends of breather tube are properly
connected.
AIR COOLING
WARNING
Hot Parts can cause severe burns.
Do not touch engine while operating or just
after stopping.
Never operate engine with heat shields or guards
removed.
Proper cooling is essential. To prevent over heating,
clean screens, cooling fi ns, and other external surfaces
of engine. Avoid spraying water at wiring harness or any
electrical components. Refer to Maintenance Schedule.
Propane EFI System
22
24 690 31 Rev. HKohlerEngines.com
WARNING
Explosive Fuel can cause fi res and severe
burns.
If a gaseous odor is detected, ventilate area
and contact an authorized service technician.
Propane is extremely fl ammable and is heavier than air
and tends to settle in low areas where a spark or fl ame
could ignite gas. Do not start or operate this engine
in a poorly ventilated area where leaking gas could
accumulate and endanger safety of persons in area.
To ensure personal safety, installation and repair of
propane fuel supply systems must be performed only
by qualifi ed propane system technicians. Improperly
installed and maintained propane equipment could
cause fuel supply system or other components to
malfunction, causing gas leaks.
Observe federal, state and local laws governing
propane fuel, storage, and systems.
Typical propane electronic fuel injection (EFI) system
and related components include:
● Vaporizer/regulator.
● Fuel fi lter.
● High pressure fuel line.
● Fuel line(s).
● Gaseous propane fuel injectors.
● Throttle body/intake manifold.
● Electronic control unit (ECU).
● Ignition coils.
● Engine (oil) temperature sensor.
● Throttle position sensor (TPS). Earlier engines have a
contacting (brushes) TPS. Later engines have a
contactless (magnetic) TPS.
● Crankshaft position sensor.
● Oxygen sensor.
● Earlier engines have a separate manifold absolute
pressure sensor (MAP) and an intake air temperature
(IAT) sensor (located in throttle body).
● Later engines have a combined temperature/manifold
absolute pressure (TMAP) sensor.
● Wire harness assembly & affi liated wiring.
● Malfunction indicator light (MIL) - optional.
FUEL RECOMMENDATIONS
Refer to Maintenance.
FUEL LINE
High pressure fuel line meeting a minimum of SAE
R7 standard must be installed on Kohler Co. engines
equipped with propane EFI system (from vaporizer/
regulator to injectors).
OPERATION
NOTE: When performing voltage or continuity tests,
avoid putting excessive pressure on or against
connector pins. Flat pin probes are
recommended for testing to avoid spreading or
bending terminals.
EFI system is designed to provide peak engine
performance with optimum fuel effi ciency and lowest
possible emissions. Ignition and injection functions
are electronically controlled, monitored and continually
corrected during operation to maintain ideal air/fuel ratio.
Central component of system is Electronic Control Unit
(ECU) which manages system operation, determining
best combination of fuel mixture and ignition timing for
current operating conditions.
Fuel is delivered from tank to integrated lock-off valve at
tank pressure. Fuel travels to vaporizer/regulator which
reduces pressure to 24-26 psi (typical). Fuel then passes
through a fi ne high pressure fi lter, is delivered from
vaporizer/regulator through high pressure fuel line into
injectors, which inject fuel into intake ports. ECU controls
amount of fuel by varying length of time that injectors
are on. This can range from 2 to over 12 milliseconds
depending on fuel requirements. Controlled injection of
fuel occurs every other crankshaft revolution, or once for
each 4-stroke cycle. When intake valve opens, air/fuel
mixture is drawn into combustion chamber, compressed,
ignited, and burned.
ECU controls amount of fuel being injected and ignition
timing by monitoring primary sensor signals for engine
temperature, speed (RPM), and throttle position (load).
These primary signals are compared to preprogrammed
maps in ECU computer chip, and ECU adjusts fuel
delivery to match mapped values. After engine reaches
operating temperature, an exhaust gas oxygen sensor
provides feedback to ECU based upon amount of
unused oxygen in exhaust, indicating whether fuel
mixture being delivered is rich or lean. Based upon this
feedback, ECU further adjusts fuel input to re-establish
ideal air/fuel ratio. This operating mode is referred to as
closed loop operation. EFI system operates closed loop
when all three of following conditions are met:
● Oil temperature is greater than 50-60°C (122-140°F).
● Oxygen sensor has warmed suffi ciently to provide a
signal (minimum 400°C, 752°F).
● Engine operation is at a steady state (not starting,
warming up, accelerating, etc.).
During closed loop operation ECU has ability to readjust
temporary and learned adaptive controls, providing
compensation for changes in overall engine condition
and operating environment, so it will be able to maintain
ideal air/fuel ratio. This system requires a minimum
engine oil temperature greater than 60-70°C (140-158°F)
to properly adapt. These adaptive values are maintained
as long as ECU is not reset.
During certain operating periods such as cold starts,
warm up, acceleration, high load, etc., a richer air/fuel
ratio is required and system operates in an open loop
mode. In open loop operation oxygen sensor output is
used to ensure engine is running rich, and controlling
adjustments are based on primary sensor signals and
programmed maps only. This system operates open
loop whenever three conditions for closed loop operation
(above) are not being met.
ECU is brain or central processing computer of entire
EFI system. During operation, sensors continuously
gather data which is relayed through wiring harness
to input circuits within ECU. Signals to ECU include:
ignition (on/off ), crankshaft position and speed (RPM),
throttle position, oil temperature, intake air temperature,
exhaust oxygen levels, manifold absolute pressure, and
battery voltage.
2324 690 31 Rev. H KohlerEngines.com
Propane EFI System
ECU compares input signals to programmed maps in
its memory to determine appropriate fuel and spark
requirements for immediate operating conditions. ECU
then sends output signals to set injector duration and
ignition timing.
ECU continually performs a diagnostic check of itself,
each of sensors, and system performance. If a fault
is detected, ECU can turn on a Malfunction Indicator
Light (MIL) (if equipped) on equipment control panel,
store fault code in its fault memory, and go into a default
operating mode. Depending on signifi cance or severity
of fault, normal operation may continue. A technician can
access stored fault code using a blink code diagnosis
fl ashed out through MIL. An optional computer software
diagnostic program is also available, see Tools and Aids.
ECU requires a minimum of 6.0 volts to operate.
To prevent engine over-speed and possible failure, a
rev-limiting feature is programmed into ECU. If maximum
RPM limit (4500) is exceeded, ECU suppresses injection
signals, cutting off fuel fl ow. This process repeats itself in
rapid succession, limiting operation to preset maximum.
Wiring harness used in EFI system connects electrical
components, providing current and ground paths for
system to operate. All input and output signaling occurs
through two special all weather connectors that attach
and lock to ECU. Connectors are Black and Grey and
keyed diff erently to prevent being attached to ECU
incorrectly.
Condition of wiring, connectors, and terminal
connections is essential to system function and
performance. Corrosion, moisture, and poor connections
are as likely cause of operating problems and system
errors as an actual component. Refer to Electrical
System for additional information.
EFI system is a 12 VDC negative ground system,
designed to operate down to a minimum of 6.0 volts.
If system voltage drops below this level, operation of
voltage sensitive components such as ECU, lock-off
valve, ignition coils, and injectors will be intermittent or
disrupted, causing erratic operation or hard starting.
A fully charged, 12 volt battery with a minimum of 350
cold cranking amps is important in maintaining steady
and reliable system operation. Battery condition and
state of charge should always be checked fi rst when
troubleshooting an operational problem.
Keep in mind that EFI-related problems are often caused
by wiring harness or connections. Even small amounts
of corrosion or oxidation on terminals can interfere with
milliamp currents used in system operation.
Cleaning connectors and grounds will solve problems
in many cases. In an emergency situation, simply
disconnecting and reconnecting connectors may clean
up contacts enough to restore operation, at least
temporarily.
If a fault code indicates a problem with an electrical
component, disconnect ECU connector and test for
continuity between component connector terminals and
corresponding terminals in ECU connector using an
ohmmeter. Little or no resistance should be measured,
indicating that wiring of that particular circuit is OK.
Crankshaft Position Sensor Bracket
B
A
A Earlier Design Bracket B Later Design Bracket
Crankshaft position sensor is essential to engine
operation; constantly monitoring rotation and speed
(RPM) of crankshaft. There are 23 consecutive teeth
cast into fl ywheel. One tooth is missing and is used
to reference crankshaft position for ECU. Inductive
crankshaft position sensor with earlier design bracket is
mounted 0.20-0.70 mm (0.008-0.027 in.) from fl ywheel.
Later design bracket requires no adjustment.
During rotation, an AC voltage pulse is created within
sensor for each passing tooth. ECU calculates engine
speed from time interval between consecutive pulses.
gap from missing tooth creates an interrupted input
signal, corresponding to specifi c crankshaft position near
BDC for cylinder #1. This signal serves as a reference
for control of ignition timing by ECU. Synchronization of
inductive speed pickup and crankshaft position takes
place during fi rst two revolutions each time engine is
started. Sensor must be properly connected at all times.
If sensor becomes disconnected for any reason, engine
will quit running.
Throttle position sensor (TPS) is used to indicate throttle
plate angle to ECU. Since throttle (by way of governor)
reacts to engine load, angle of throttle plate is directly
related to load on engine.
Mounted on throttle body and operated directly off end
of throttle shaft, TPS works as a potentiometer, varying
voltage signal to ECU in direct correlation to angle
of throttle plate. This signal, along with other sensor
signals, is processed by ECU and compared to internal
preprogrammed maps to determine required fuel and
ignition settings for amount of load.
Correct position of TPS is established and set at factory.
Do not loosen TPS or alter mounting position unless
absolutely required by fault code diagnosis. If TPS
is loosened or repositioned, appropriate TPS Learn
Procedure must be performed to re-establish baseline
relationship between ECU and TPS.
Engine (oil) temperature sensor is used by system to
help determine fuel requirements for starting (a cold
engine needs more fuel than one at or near operating
temperature).
Mounted in breather cover, it has a temperature-
sensitive resistor that extends into oil fl ow. Resistance
changes with oil temperature, altering voltage sent
to ECU. Using a table stored in its memory, ECU
correlates voltage drop to a specifi c temperature. Using
fuel delivery maps, ECU then knows how much fuel is
required for starting at that temperature.
Propane EFI System
24
24 690 31 Rev. HKohlerEngines.com
Earlier engines have a separate intake air temperature
(IAT) sensor (located in throttle body) and a manifold
absolute pressure (MAP) sensor. Later engines have
a combined temperature/manifold absolute pressure
(TMAP) sensor.
Intake Air Temperature (IAT) sensor is a thermally
sensitive resistor that exhibits a change in electrical
resistance with a change in its temperature. When
sensor is cold, resistance of sensor is high. As sensor
warms up, resistance drops and voltage signal
increases. From voltage signal, ECU can determine
temperature of intake air.
Purpose of an air temperature sensor is to help ECU
calculate air density. Higher air temperature less dense
air becomes. As air becomes less dense ECU knows
that it needs to lessen fuel fl ow to achieve correct air/fuel
ratio. If fuel ratio was not changed engine would become
rich, possibly losing power and consuming more fuel.
Manifold absolute pressure (MAP) sensor provides
immediate manifold pressure information to ECU.
MAP measures diff erence in pressure between outside
atmosphere and vacuum level inside intake manifold
and monitors pressure in manifold as primary means
of detecting load. Data is used to calculate air density
and determine engine's mass air fl ow rate, which in
turn determines required ideal fueling. MAP also stores
instant barometric pressure reading when key is turned
ON.
Later engines have a Temperature/Manifold Absolute
Pressure (TMAP) sensor. This is an integrated sensor
that checks both intake air temperature and manifold
absolute pressure. This combined sensor is located in
intake manifold.
Oxygen sensor functions like a small battery, generating
a voltage signal to ECU based upon diff erence in oxygen
content between exhaust gas and ambient air.
Tip of sensor, protruding into exhaust gas, is hollow.
Outer portion of tip is surrounded by exhaust gas, with
inner portion exposed to ambient air. When oxygen
concentration on one side of tip is diff erent than that of
other side, a voltage signal up to 1.0 volt is generated
and sent to ECU. Voltage signal tells ECU if engine is
straying from ideal fuel mixture, and ECU then adjusts
injector pulse accordingly.
Oxygen sensor functions after being heated to a
minimum of 400°C (752°F). A heater inside sensor heats
electrode to optimum temperature in about 10 seconds.
Oxygen sensor receives ground through wire, eliminating
need for proper grounding through muffl er. If problems
indicate a bad oxygen sensor, check all connections and
wire harness. Oxygen sensor can also be contaminated
by leaded fuel, certain RTV and/or other silicone
compounds, fuel injector cleaners, etc. Use only those
products indicated as O2 Sensor Safe.
Fuel injectors mount into intake manifold, and high
pressure fuel line attaches to them at top end.
Replaceable O-rings on both ends of injector prevent
external fuel leakage and also insulate it from heat and
vibration. A special clip connects each injector to high
pressure fuel line and holds it in place. O-rings and
retaining clip must be replaced any time fuel injector is
separated from its normal mounting position.
When key switch is on, lock-off valve will open briefl y
and allow fuel into system at 24-26 psi, and voltage is
present at injector. At proper instant, ECU completes
ground circuit, energizing injector. Valve needle in
injector is opened electromagnetically, and pressure in
high pressure fuel line forces fuel down through inside.
Director plate at tip of injector contains a series of
calibrated openings which directs fuel into manifold.
Injectors have sequential fueling that open and close
once every other crankshaft revolution. Amount of fuel
injected is controlled by ECU and determined by length
of time valve needle is held open, also referred to as
injection duration or pulse width. Time injector is open
(milliseconds) may vary in duration depending on speed
and load requirements of engine.
A high-voltage, solid-state, battery ignition system is
used with EFI system. ECU controls ignition output and
timing through transistorized control of primary current
delivered to coils. Based on input from crankshaft
position sensor, ECU determines correct fi ring point
for speed at which engine is running. At proper instant,
it interrupts fl ow of primary current in coil, causing
electromagnetic fl ux fi eld to collapse. Flux collapse
induces an instantaneous high voltage in coil secondary
which is strong enough to bridge gap on spark plug.
Each coil fi res every other revolution.
EFI engines are equipped with either a 20 or 25 amp
charging system to accommodate combined electrical
demands of ignition system and specifi c application.
Charging system troubleshooting information is provided
in Electrical System.
When key switch is turned ON and all safety switch
requirements are met, ECU activates lock-off valve for
about six seconds, which pressurizes system for start-
up. If key switch is not promptly turned to start position,
engine fails to start, or engine is stopped with key
switch ON (as in case of an accident), ECU switches off
lock-off valve preventing continued delivery of fuel. In
this situation, MIL will go on, but it will go back off after
4 cranking revolutions if system function is OK. Once
engine is running, lock-off valve remains on.
There are two fi lters in system, one on inlet of vaporizer/
regulator will be a 30-micron button fi lter, and one after
will be a special metal 10-micron fi lter. Be sure to use
metal propane 10-micron fi lter for replacement.
High pressure fuel line is an assembly of hoses, injector
caps and a fuel connector to vaporizer/regulator. High
pressure fuel line feeds fuel to top of injectors through
injector caps. Caps are fastened to intake manifold and
injectors are locked into place. A small retaining clip
provides a secondary lock.
2524 690 31 Rev. H KohlerEngines.com
Propane EFI System
High pressure fuel line is serviced as a complete
assembly to prevent tampering and safety hazards.
Components are not individually serviceable.
Vacuum hose connects vaporizer/regulator to throttle
body, compensating regulated pressure for air cleaner
condition.
EFI engines have no carburetor, so throttle function
(regulate incoming combustion airfl ow) is achieved with
a throttle valve in a separate throttle body attached to
intake manifold. Throttle body/intake manifold provides
mounting for fuel injectors, throttle position sensor, MAP
sensor, intake air temperature sensor, high pressure fuel
line, idle speed screw, and air cleaner assembly.
Idle speed is only adjustment that may be performed on
EFI system. Standard idle speed setting for EFI engines
is 1500 RPM, but certain applications might require
a diff erent setting. Check equipment manufacturer’s
recommendation.
For starting and warm up, ECU will adjust fuel and
ignition timing, based upon ambient temperature, engine
temperature, and loads present. In cold conditions,
idle speed will probably be diff erent than normal for a
few moments. Under other conditions, idle speed may
actually start lower than normal, but gradually increase
to established setting as operation continues. Do not
attempt to circumvent this warm up period, or readjust
idle speed during this time. Engine must be completely
warmed up, in closed loop operating mode for accurate
idle adjustment.
IMPORTANT NOTES!
● Cleanliness is essential and must be maintained at all
times when servicing or working on EFI system. Dirt,
even in small quantities, can cause signifi cant
problems.
● Clean any joint or fi tting with parts cleaning solvent
before opening to prevent dirt from entering system.
● Always depressurize fuel system before disconnecting
or servicing any fuel system components. Shut off tank
valve. If possible, run engine in a well-ventilated area
until fuel system is empty and engine stops. If unable
to run engine, work in a well-ventilated area and
carefully loosen inlet fuel fi tting on vaporizer/regulator,
slowly venting off fuel from line. When fuel is
dispensed, retighten fi tting and remove quick connect
fi tting to allow fuel to escape from line.
● Never attempt to service any fuel system component
while engine is running or ignition switch is ON.
● Do not use compressed air if system is open. Cover
any parts removed and wrap any open joints with
plastic if they will remain open for any length of time.
New parts should be removed from their protective
packaging just prior to installation.
● Avoid direct water or spray contact with system
components.
● Do not disconnect or reconnect ECU wiring harness
connector or any individual components with ignition
on. This can send a damaging voltage spike through
ECU.
● Do not allow battery cables to touch opposing
terminals. When connecting battery cables attach
positive (+) cable to positive (+) battery terminal fi rst,
followed by negative (-) cable to negative (-) battery
terminal.
● Never start engine when cables are loose or poorly
connected to battery terminals.
● Never disconnect battery while engine is running.
● Never use a quick battery charger to start engine.
● Do not charge battery with key switch ON.
● Always disconnect negative (-) battery cable before
charging battery, and also unplug harness from ECU
before performing any welding on equipment.
Exhaust System PCV680LE, PCV740LE
NOTE: Overfueling can cause overheating of muffl er
and premature failure.
● PCV680LE and PCV740LE engines are designed with
lower emissions with a catalyst in exhaust system. If
run quality, including misfi ring, is in question, shut
engine down and obtain service right away.
Propane EFI System
26
24 690 31 Rev. HKohlerEngines.com
ELECTRICAL COMPONENTS
Electronic Control Unit (ECU)
Pinout of ECU
Black Connector Side
Pin # Function
1 Ignition Coil #1 Ground
2 Battery Ground
3 Diagnostic Communication Line
4 Speed Sensor input
5 Fuel Injector Output #1 Ground
6 Fuel Injector Output #2 Ground
7 Oxygen Sensor Heater
8
Intake Air Temperature (IAT) sensor or TMAP
sensor input
9 Fuel Lock-Off Ground
10
Ground for TPS, IAT and MAP sensors or TMAP
sensor, O2 and Oil sensors
11 MAP sensor or TMAP sensor input
12 Throttle Position Sensor (TPS) input
13 Speed Sensor Ground
14 Oil Temperature Sensor input
15 Ignition Switch (Switched +12V)
16
Power for TPS sensor, MAP sensor or TMAP
sensor (+5V)
17 Oxygen Sensor (O2) input
18 Battery Power (Permanent +12V)
Grey Connector Side
Pin # Description
1 Not Used
2 Not Used
3 Malfunction Indicator Light (MIL) Ground
4 Not Used
5 Not Used
6 Not Used
7 Not Used
8 Not Used
9 Battery Ground
10 Ignition Coil #2 Ground
11 Not Used
12 Not Used
13 Not Used
14 Safety Switch Ground
15 Not Used
16 ECU
17 Fuel Lock-Off Control (+12V)
18 Not Used
BLACK CONNECTOR SIDE GREY CONNECTOR SIDE
ECU
Pinout of ECU
2724 690 31 Rev. H KohlerEngines.com
Propane EFI System
Never attempt to disassemble ECU. It is sealed to
prevent damage to internal components. Warranty is
void if case is opened or tampered with in any way.
All operating and control functions within ECU are
preset. No internal servicing or readjustment may
be performed. If a problem is encountered, and you
determine ECU to be faulty, contact your source of
supply.
ECU pins are coated at factory with a thin layer of
electrical grease to prevent fretting and corrosion. Do not
attempt to remove grease from ECU pins.
Relationship between ECU and throttle position sensor
(TPS) is very critical to proper system operation. If
TPS or ECU is changed, or mounting position of TPS
is altered, appropriate TPS Learn Procedure must be
performed to restore synchronization.
Any service to ECU or TPS/Throttle Body (including idle
speed increase over 300 RPM), should include ECU
Reset.
This will clear all trouble codes, all closed loop learned
off sets, all max values, and all timers besides permanent
hour meter.
This system will NOT reset when battery is
disconnected!
ECU Reset Procedure
1. Turn key/ignition OFF.
2. Install Red wire jumper from Kohler EFI service kit
on to service port (connect white wire to black wire in
4 way diagnostic port).
3. Turn key/ignition ON, then OFF and count 10
seconds.
4. Turn key/ignition ON, then OFF and count to 10
seconds a second time.
5. Remove Red wire jumper. Turn key/ignition ON, then
OFF and count to 10 seconds a third time. ECU is
reset.
A TPS Learn Procedure must be performed after ECU
Reset.
TPS Learn Procedure
1. Turn idle screw clockwise one full turn prior to key/
ignition ON after ECU Reset.
2. Start engine, run at low idle until engine is warm.
3. Idle speed must be above 1500 RPM. If below 1500
RPM, turn idle screw up to 1700 RPM and then shut
down engine and perform ECU Reset again.
4. Adjust idle speed down to 1500 RPM. Allow engine
to dwell at 1500 RPM for about 3 seconds.
5. After this, adjust idle speed to fi nal specifi ed speed
setting.
6. Turn key/ignition OFF and count to 10 seconds.
Learn procedure is complete.
Propane EFI System
28
24 690 31 Rev. HKohlerEngines.com
AB AB ABC DABC 1 2 312ABC AB12
19
1018
19
1018
312
6
4
5
12
3
4
312
1
2
Wiring Harness
EFI Wiring Diagram 6-Terminal Connector (engines with separate MAP sensor and intake air temperature sensor)
A Red B Red/Black C Red/White D Yellow E Light Green
F Dark Green G Dark Blue H Purple I Pink J Tan
K White L Grey M Black N Stator O Rectifi er-Regulator
P 30A Fuse Q Battery R
Vaporizer/Regulator/
Lock-Off
S 6-Terminal Connector T Starter Motor
U Oil Pressure Switch V MIL W 10A Fuse X Black Connector Y Grey Connector
Z Fuel Injector #1 AA Fuel Injector #2 AB Ignition Coil #1 AC Ignition Coil #2 AD
Crankshaft Position
Sensor
AE Oxygen Sensor AF
Throttle Position
Sensor
AG
Manifold Absolute
Pressure Sensor
AH
Oil Temperature
Sensor
AI
Intake Air
Temperature Sensor
AJ Diagnostic Connector
C
J
G
B
F
B
B
M B
H
H
D B
F
H
M
M
L
G L
M
E
F
M
M
J
K
M G
B
K
W
AP
H
I
V
W
O
Y
M
M
A
N
X
Q
R
T
A
U
Z
AA
AB
AC
AD
AE
AF
AG
AH
AI
AJ
G
S
M
B
F
2924 690 31 Rev. H KohlerEngines.com
Propane EFI System
AB AB ABC DABC 1 2 312ABC AB12
1
2
19
1018
19
1018
ED
A
C
B
12
3
4
312
WB
A
D
M
W
K
I
M
S
P
H
Y
O
C
A
K
X
N
Q R
J
G
U
T
G B F B B M B H H D B F H M M L G L M E F M
M
J
K
M
G
B
Z
AJ
AI
AH
AG
AFAEADACAB
AA
V
D
EFI Wiring Diagram 5-Terminal Connector and Optional Key Switch (engines with separate MAP sensor and intake air temperature sensor)
A Red B Red/Black C Red/White D Yellow E Light Green
F Dark Green G Dark Blue H Purple I Pink J Tan
K White L Grey M Black N Stator O Rectifi er-Regulator
P 30A Fuse Q Battery R
Vaporizer/Regulator/
Lock-Off
S 5-Terminal Connector T Starter Motor
U Oil Pressure Switch V MIL W 10A Fuse X Black Connector Y Grey Connector
Z Fuel Injector #1 AA Fuel Injector #2 AB Ignition Coil #1 AC Ignition Coil #2 AD
Crankshaft Position
Sensor
AE Oxygen Sensor AF
Throttle Position
Sensor
AG
Manifold Absolute
Pressure Sensor
AH
Oil Temperature
Sensor
AI
Intake Air
Temperature Sensor
AJ Diagnostic Connector
Propane EFI System
30
24 690 31 Rev. HKohlerEngines.com
EFI Wiring Diagram 6-Terminal Connector (engines with TMAP sensor)
AB AB ABC DABC 1 2 A B C
19
1018
19
1018
312
6
4
5
12
3
4
312
12312
4
1
2
A Red B Red/Black C Red/White D Yellow E Light Green
F Dark Green G Dark Blue H Purple I Pink J Tan
K White L Grey M Black N Stator O Rectifi er-Regulator
P 30A Fuse Q Battery R
Vaporizer/Regulator/
Lock-Off
S 6-Terminal Connector T Starter Motor
U Oil Pressure Switch V MIL (Optional) W 10A Fuse X Black Connector Y Grey Connector
Z Fuel Injector #1 AA Fuel Injector #2 AB Ignition Coil #1 AC Ignition Coil #2 AD
Crankshaft Position
Sensor
AE Oxygen Sensor AF
Throttle Position
Sensor
AG TMAP Sensor AH
Oil Temperature
Sensor
AI Diagnostic Connector
C
J
G
B
F
B B M B
H
H
D
B F H
M
M
L
G
L
M
E
F
M
J
K
M G
B
K
W
A
P
H
I
V
W
O
Y
M
M
N
X
Q
R
T
A
U
Z
AA
AB
AC AD
AE
AF
AG
AH
AI
G
F
M
B
S
3124 690 31 Rev. H KohlerEngines.com
Propane EFI System
EFI Wiring Diagram 5-Terminal Connector and Optional Key Switch (engines with TMAP sensor)
AB AB ABC DABC 12 ABC
19
1018
19
1018
ED
A
C
B
12
3
4
312
312
4
12
1
2
WB
A
D
M
W
K
I
M
S
P
H
Y
O
C
A
K
X
N
Q
R
J
G
U
T
G B F B B M B H H D B F H M M L G
L M
E
F
M
J
K
M
G
B
Z
AI
AH
AG
AFAEADAC
AB
AA
V
D
A Red B Red/Black C Red/White D Yellow E Light Green
F Dark Green G Dark Blue H Purple I Pink J Tan
K White L Grey M Black N Stator O Rectifi er-Regulator
P 30A Fuse Q Battery R
Vaporizer/Regulator/
Lock-Off
S 5-Terminal Connector T Starter Motor
U Oil Pressure Switch V MIL (Optional) W 10A Fuse X Black Connector Y Grey Connector
Z Fuel Injector #1 AA Fuel Injector #2 AB Ignition Coil #1 AC Ignition Coil #2 AD
Crankshaft Position
Sensor
AE Oxygen Sensor AF
Throttle Position
Sensor
AG TMAP Sensor AH
Oil Temperature
Sensor
AI Diagnostic Connector
Propane EFI System
32
24 690 31 Rev. HKohlerEngines.com
Crankshaft Position Sensor
B
A
A Earlier Design Bracket B Later Design Bracket
A sealed, non-serviceable assembly. If Fault Code
diagnosis indicates a problem within this area, test and
correct as follows.
1. Check mounting and air gap of crankshaft position
sensor.
Earlier design bracket has slots to set air gap of
0.20-0.70 mm (0.008-0.027 in.).
Later design bracket is not adjustable, but if gap is
greater than 2.794 mm (0.110 in.) check bracket or
sensor for damage.
2. Inspect wiring and connections for damage or
problems.
3. Make sure engine has resistor type spark plugs.
4. Disconnect Black connector from ECU.
5. Connect an ohmmeter between #4 and #13 pin
terminals. A resistance value of 325-395 Ω at room
temperature (20°C, 68°F) should be obtained. If
resistance is correct, check mounting, air gap,
fl ywheel teeth (damage, run-out, etc.), and fl ywheel
key.
6. Disconnect crankshaft position sensor connector
from wiring harness. Test resistance between
terminals. A reading of 325-395 Ω should again be
obtained.
a. If resistance is incorrect, remove screws securing
sensor to mounting bracket and replace sensor.
b. If resistance in step 5 was incorrect, but
resistance of sensor alone was correct, test wire
harness circuits between sensor connector
terminals and corresponding pin terminals (#4
and #13) in main connector. Correct any
observed problem, reconnect sensor, and
perform step 5 again.
7. When fault is corrected and engine starts, clear fault
codes following ECU Reset procedure.
Throttle Position Sensor (TPS)
Earlier engines were built with a contacting (brush) type
TPS. Later engines are built with a contactless (magnet)
type TPS. Both designs have same three wires attached;
a 5 volt supply, a ground, and a signal wire. However,
these designs are not interchangeable. Follow proper
testing information based on sensor type.
Contacting (Brush) Type TPS
Resistance Table
Throttle
Position
Between
Terminal
Resistance
Value (Ω)
Continuity
Closed A & C 1400-1800 Yes
Full with
Stop Pin
A & C 3200-4100 Yes
Full without
Stop Pin
A & C 4600-5200 Yes
Any A & B 3000-7000 Yes
TPS is a sealed, non-serviceable assembly. If diagnosis
indicates a bad sensor, complete replacement is
necessary. If a blink code indicates a problem with TPS,
it can be tested as follows:
1. Counting number of turns, back out idle speed
adjusting screw (counterclockwise) until throttle
plates can be closed completely. Write this number
down for reference later.
2. Disconnect Black connector from ECU, but leave
TPS mounted to throttle body.
3. a. Use an ohmmeter and connect red (positive)
ohmmeter lead to Black pin 12 terminal and black
(negative) ohmmeter lead to Black pin 10 terminal
to test.
b. Hold throttle closed and check resistance. It
should be 1400-1800 Ω.
4. Leave leads connected to pin terminals as described
in step 3. Rotate throttle shaft slowly to full throttle
position. Monitor dial during rotation for indication of
any momentary short or open circuits. Note
resistance at full throttle position. It should be
4600-5200 Ω without a stop pin, or 3200-4100 Ω
with a stop pin.
5. Disconnect main wiring harness connector from
TPS, leaving TPS assembled to throttle body. Refer
to Resistance Table and perform resistance checks
indicated between terminals in TPS switch, with
throttle in positions specifi ed.
If resistance values in steps 3, 4, and 5 are within
specifi cations, go to step 6.
If resistance values are not within specifi cations, or a
momentary short or open circuit was detected during
rotation (step 4), TPS needs to be replaced, go to
step 7.
6. Check TPS circuits (input, ground) between TPS
plug and main harness connector for continuity,
damage, etc. Input pin is 12 and ground is pin 10.
a. Repair or replace as required.
b. Turn idle speed screw back in to its original
setting.
c. Reconnect connector plugs, start engine and
retest system operation.
3324 690 31 Rev. H KohlerEngines.com
Propane EFI System
7. Remove two mounting screws from TPS. Save
screws for reuse. Remove and discard faulty TPS.
Install replacement TPS and secure with original
mounting screws.
a. Reconnect Black and TPS connector plugs.
b. Perform TPS Learn Procedure integrating new
sensor to ECU.
Contactless (Magnet) Type TPS
TPS is a sealed, non-serviceable assembly. If diagnosis
indicates a bad sensor, complete replacement is
necessary. Magnet that sensor detects is separate, and
can be replaced or reused. If a blink code indicates a
problem with TPS, it can be tested as follows:
Diagnostics of sensor: ECU will still have electrical faults
captured in fault codes: P0122 & P0123. These electrical
faults still have same meaning as with prior sensor,
P0122 detecting low voltage, open circuit, and P0123 for
high voltage conditions between ECU, wire harness, and
sensor. Tip: when working with any electrical connection,
remember to keep connections clean & dry. This is best
accomplished by cleaning connection thoroughly prior
to disassembly. Contaminated sensor connections can
cause premature engine faults. Functionally testing
sensor can no longer be done with simple resistance
checks. If either of these two faults is present or a TPS
fault is suspected, recommended diagnostic test is as
follows:
If a computer with diagnostic software is available
Observe throttle percent and raw TPS values through
diagnostic software. With diagnostic software
communicating to ECU and key ON engine not running,
these values can be observed while throttle is moved
from closed to full open position. There should be a
smooth and repeatable throttle percent value starting
at closed position reading between 0 (about 6.5%) to
WOT position reading 93 (100%). If one of these values
is outside of specifi ed range and output transitions in a
smooth manner, reset ECU and run test again. Since
there is no longer any wear elements inside sensor, most
likely faults will be in electrical connections between
sensor and wire harness and wire harness to ECU. With
service software communicating to ECU and engine not
running, a small load or gentle back and forth motion can
be applied to connectors or wires just outside connectors
to detect a faulty connection.
If only a volt meter is available
Measure voltage supply to sensor from ECU. This
voltage should be 5.00 +/- 0.20 volts. This can be
measured by gently probing terminals B & C on harness
side with TPS connector removed from TPS and key
ON. This will generate a P0122 fault that can be cleared
with an ECU reset. If voltage is low, battery, harness and
ECU should be investigated. If supply voltage is good,
plug sensor back into harness. Probe sensor signal
wire with volt meter, terminal A at TPS or pin Black 12
at ECU. This signal should start between 0.6-1.2 volts
at low idle and grow smoothly as throttle is opened to
4.3-4.8 volts at full open (WOT). Since there is no longer
any wear elements inside sensor, most likely faults will
be in electrical connections between sensor and wire
harness and wire harness to ECU.
Replace Magnet Assembly
A
B
A Magnet Assembly B
Magnet Installation
Depth
Magnet assembly is captured in a small plastic housing
that is press fi t to end of throttle shaft. This generally
does not need replacement. If replacement is required,
can be replaced as follows:
1. Remove sensor from throttle body, exposing round
magnet assembly.
2. A pair of fl at blade screw drivers or a spanner tool
can be used to pry this off shaft. Caution should be
used to avoid damage to machined fl at surface that
sensor seals against. Also, make sure throttle blade
is in full open position to avoid driving throttle blade
into throttle bore causing damage to blade and/or
bore.
3. When replacing magnet assembly, alignment is
critical. There is a D-shaped drive feature on end of
shaft and a matching pocket in magnet assembly.
On outer diameter of magnet assembly is a notch
that aligns with center of fl at feature of D. Align this
notch and fl at of D feature in shaft and preassemble
parts.
4. With throttle blade in full open position (WOT), press
magnet assembly fully on to throttle shaft. Full
insertion can be checked by measuring height from
throttle body sensor mounting face to end of magnet
assembly. This should be no more than 8.6 mm
(0.338 in.). Installation process requires signifi cant
force, so take care that all parts are aligned. Tapping
magnet assembly on can fracture/damage brittle
magnet within assembly and throttle body assembly
and is NOT RECOMMENDED.
Propane EFI System
34
24 690 31 Rev. HKohlerEngines.com
Engine (Oil) Temperature Sensor
A sealed, non-serviceable assembly. A faulty sensor
must be replaced. If a blink code indicates a problem
with temperature sensor, it can be tested as follows:
1. Remove temperature sensor from breather cover
and cap or block sensor hole.
2. Wipe sensor clean and allow it to reach room
temperature (25°C, 77°F).
3. Unplug Black connector from ECU.
4. With sensor still connected, check temperature
sensor circuit resistance between Black pin 10 and
14 terminals. Value should be 9000-11000 Ω.
5. Unplug sensor from wire harness and check sensor
resistance separately across two pins. Resistance
value should again be 9000-11000 Ω.
a. If resistance is out of specifi cations, replace
temperature sensor.
b. If it is within specifi cations, proceed to Step 6.
6. Check circuits (input, ground), from wire harness
connector to sensor plug for continuity, damage, etc.
Connect one ohmmeter lead to Black pin 14 in wire
harness connector (as in step 4). Connect other lead
to terminal #1 in sensor plug. Continuity should be
indicated. Repeat test between Black pin 10 and
terminal #2 in sensor plug.
Earlier engines have a separate intake air
temperature (IAT) sensor (located in throttle body)
and a manifold absolute pressure (MAP) sensor
(located in intake manifold).
Intake Air Temperature Sensor
A non-serviceable component. Complete replacement is
required if it is faulty. Sensor and wiring harness can be
checked as follows.
1. Remove temperature sensor from throttle body.
2. Allow it to reach room temperature (20°C, 68°F).
3. Unplug Black connector from ECU.
4. With sensor still connected, check temperature
sensor circuit resistance between Black pin 10 and 8
pin terminals. Value should be 3100-3900 Ω.
5. Unplug sensor from wire harness and check sensor
resistance separately across two pins. Resistance
value should again be 3100-3900 Ω.
a. If resistance is out of specifi cations, replace
temperature sensor.
b. If it is within specifi cations, proceed to Step 6.
6. Check circuits (input, ground), from main harness
connector to sensor plug for continuity, damage, etc.
Connect one ohmmeter lead to Black pin 8 in main
harness connector (as in step 4). Connect other lead
to terminal #1 in sensor plug. Continuity should be
indicated. Repeat test between Black pin 10 and
terminal #2 in sensor plug.
Manifold Absolute Pressure Sensor (MAP)
A sealed, non-serviceable assembly. A faulty sensor
must be replaced. If a blink code indicates a problem
with manifold absolute pressure sensor, it can be tested
as follows:
1. Make sure all connections are making proper
contact and are free of dirt and debris. Remove
blower housing. Slide locking tab out and pull off
manifold absolute pressure connector. Turn key
switch to ON and check with a volt meter by
contacting red lead to pin 1 and black lead to pin 2.
There should be 5 volts present, indicating ECU and
wiring harness are functioning.
2. Check continuity in wire harness. Ohms between Pin
3 at sensor connector and Black pin 11 connector at
ECU should be near zero ohms. If no continuity is
measured or very high resistance, replace wire
harness.
3. Check to make sure intake manifold is not loose and
MAP sensor is not loose. Loose parts would allow a
vacuum leak, making MAP sensor report misleading
information to ECU.
a. Tighten all hardware and perform an ECU Reset
and a TPS Learn Procedure to see if MIL will
display a fault with MAP sensor again. If MIL fi nds
a fault with MAP sensor, replace it.
Later engines have a combined temperature/
manifold absolute pressure (TMAP) sensor (located
in intake manifold).
Temperature/Manifold Absolute Pressure (TMAP)
Sensor
A sealed non-serviceable integrated sensor that checks
both intake air temperature and manifold absolute
pressure. Complete replacement is required if it is faulty.
Sensor and wiring harness can be checked as follows.
If a blink code indicates a problem with Intake Air
Temperature (TMAP) Sensor Circuit (P0112 or P0113), it
can be tested as follows:
1. Remove TMAP sensor from intake manifold.
2. Allow it to reach room temperature (20°C, 68°F).
3. Unplug Black connector from ECU.
4. With sensor still connected, check temperature
sensor circuit resistance between Black pin 10 and 8
pin terminals. Value should be 1850-2450 Ω.
5. Unplug sensor from wire harness and check sensor
resistance separately across pin. Resistance value
should again be 1850-2450 Ω.
a. If resistance is out of specifi cations, check local
temperature. Sensor resistance will go down as
temperature is higher. Replace TMAP sensor if
determined to be faulty.
b. If it is within specifi cations, proceed to Step 6.
3524 690 31 Rev. H KohlerEngines.com
Propane EFI System
6. Check circuits (input, ground), from main harness
connector to sensor plug for continuity, damage, etc.
Connect one ohmmeter lead to Black pin 8 in main
harness connector (as in step 4). Connect other lead
to terminal #3 in sensor plug. Continuity should be
indicated. Repeat test between Black pin 10 and
terminal #4 in sensor plug.
7. Reinstall sensor.
If a blink code indicates a problem with Manifold
Absolute Pressure (TMAP) Sensor Circuit (P0107 or
P0108), it can be tested as follows:
1. Make sure all connections are making proper
contact and are free of dirt and debris. Slide locking
tab out and pull off TMAP connector. Turn key switch
to ON and check with a volt meter by contacting red
lead to pin 1 and black lead to pin 2. There should
be 5 volts present, indicating ECU and wiring
harness are functioning.
2. Check continuity in wire harness. Ohms between Pin
3 at sensor connector and Black pin 11 connector at
ECU should be near zero ohms. If no continuity is
measured or very high resistance, replace wire
harness.
3. Check to make sure intake manifold is not loose and
TMAP sensor is not loose. Loose parts would allow
a vacuum leak, making TMAP sensor report
misleading information to ECU.
a. Tighten all hardware and perform an ECU Reset
and a TPS Learn Procedure to see if MIL will
display a fault with sensor again. If MIL fi nds a
fault with TMAP sensor, replace it.
Oxygen Sensor (O
2
)
Components
Pin D
Pin C
Pin B
Pin A
Cutaway Oxygen Sensor Components (O
2
)
A
B
C
D
E
F
G
A Protection Shield B
Planar Element
and Heater
C Lower Insulator D
Stainless Steel
Housing
E Upper Insulator F
Terminal Connection
to Element
G
High Temp
Water Seal
Temperature must be controlled very accurately and gas
constituents measured to a high degree of accuracy for
absolute sensor measurements. This requires laboratory
equipment to determine a good or bad sensor in fi eld.
Furthermore, as with most devices, intermittent problems
are diffi cult to diagnose. Still, with a good understanding
of system and sensor, it is possible to diagnose many
sensor problems in fi eld.
Using diagnostic software connected to ECU is a useful
technique for observing sensor performance. However,
user must understand that such software reads a signal
generated by ECU. If there is an ECU or wiring problem,
readings could be misinterpreted as a sensor problem.
Digital nature of signal to software means that it is not
reading continuous output of sensor. A voltmeter can
also be used as an eff ective tool in diagnosing sensors.
It is advisable to use an electronic meter such as a
digital voltmeter. Simple mechanical meters may place
a heavy electrical load on sensor and cause inaccurate
readings. Since resistance of sensor is highest at
low temperatures, such meters will cause largest
inaccuracies when sensor is in a cool exhaust.
Visual Inspection
1. Look for a damaged or disconnected sensor-to-
engine harness connection.
2. Look for damage to sensor lead wire or associated
engine wiring due to cutting, chaffi ng or melting on a
hot surface.
3. Disconnect sensor connector and look for corrosion
in connector.
4. Try reconnecting sensor and observe if problem has
cleared.
5. Correct any problems found during visual check.
Propane EFI System
36
24 690 31 Rev. HKohlerEngines.com
Sensor Signal Observation
NOTE: Do not cut into or pierce sensor or engine
wiring to make this connection. Sensor
produces a very small signal. Corrosion or
damage to wiring could lead to an incorrect
signal because of repairs or contamination to
sensor.
1. Using a voltmeter, observe voltage between Pin C
and Pin D before engine is started. With key ON,
and sensor unplugged, voltage should read about
5.0 volts. With sensor attached, using diagnostic
software, voltage should read about 1.0 volt. This
voltage is generated by ECU. If it is not present,
there is a short in associated wiring and corrective
action should be taken. If voltage still is not present,
there is a problem with ECU or engine harness.
2. Reconnect sensor and start engine. Run engine at
suffi cient speed to bring sensor up to operating
temperature. Maintain for 1 to 2 minutes to ensure
that engine has gone closed loop. Once in closed
loop, sensor voltage should cycle between about
100 to 250 mv (low speed idle) and 700 to 900 mv
(high speed no load). If this cycling is not observed,
a determination must be made, if problem is with
engine or sensor.
3. Check engine harness for battery voltage on heater
circuit.
Removal Inspection
NOTE: Apply anti-seize compound only to threads.
Anti-seize compound will aff ect sensor
performance if it gets into lower shield of
sensor.
1. If sensor has heavy deposits on lower shield,
engine, oil, or fuel may be source.
2. If heavy carbon deposits are observed, incorrect
engine fuel control may be occurring.
3. If sensor is at room temperature, measure between
signal leads, black wire (Pin C) and grey wire (Pin D)
attached to sensor. If resistance is less than one
megohm, sensor has an internal short.
4. With sensor at room temperature measure heater
circuit resistance, purple wire (Pin A) and white wire
(Pin B), resistance should be 8.1-11.1 Ω.
5. If a damaged sensor is found, identify root cause,
which may be elsewhere in application. Refer to
Troubleshooting-Oxygen Sensor (O
2
) table.
6. A special "dry to touch" anti-seize compound is
applied to all new oxygen sensors at factory. If
recommended mounting thread sizes are used, this
material provides excellent anti-seize capabilities
and no additional anti-seize is needed. If sensor is
removed from engine and reinstalled, anti-seize
compound should be reapplied. Use an oxygen
sensor safe type anti-seize compound. It should be
applied according to directions on label.
3724 690 31 Rev. H KohlerEngines.com
Propane EFI System
Troubleshooting-Oxygen Sensor (O
2
)
Condition Possible Cause Conclusion
Low voltage output. Shorted sensor or sensor circuit.
Shorted lead wire.
Wiring shorted to ground.
Replace sensor or repair wiring.
Contamination of air reference. Remove source of external
contamination, protect air reference
area.
Air leak at sensor or gasket, sensor
upper shield damage.
Use recommended torque at
installation, replace gasket or sensor.
Revise application exhaust.
Shield sensor from damage.
High voltage output. Silica poisoning. Replace sensor.
Contaminated fuel. Use high quality fuel.
Engine problem; misfi re. Correct cause of misfi re.
Excessive rich air/fuel ratio. Check for high fuel pressure
Leaking injector
Wiring shorted to voltage. Repair wiring.
Open circuit, no activity from sensor. Broken element.
Sensor dropped.
Hard blow to engine or exhaust
system.
Defective sensor.
Thermal shock.
Replace sensor.
Slow time response. Open heater circuit.
Improper handling.
Carbon deposits.
Replace sensor.
Incorrect or contaminated fuel. Use high quality fuel.
Excessive engine oil consumption
causing exhaust contamination or
other exhaust side contamination.
Correct engine condition.
Heater circuit open/shorted or out of
specifi cation.
Repair short in harness wires, replace
sensor.
Propane EFI System
38
24 690 31 Rev. HKohlerEngines.com
Fuel Injectors
WARNING
High Pressure Fluids can puncture skin and
cause severe injury or death.
Do not work on fuel system without proper
training or safety equipment.
Fluid puncture injuries are highly toxic and hazardous.
If an injury occurs, seek immediate medical attention.
Details
B
H
E
C
A
D
G
F
A Electrical Connection B Upper O-ring
C
Inlet Filter/Calibration
Tube Assembly
D Solenoid Winding
E Armature F Valve Housing
G Valve Seat H Lower O-ring
I Director Plate
NOTE: Do not apply voltage to fuel injector(s).
Excessive voltage will burn out injector(s). Do
not ground injector(s) with ignition ON.
Injector(s) will open/turn on if relay is energized.
NOTE: When cranking engine with injectors
disconnected, fault codes will be registered in
ECU and will need to be cleared using software
fault clear or an ECU Reset and TPS Learn
Procedure.
Injector problems typically fall into three general
categories: electrical, dirty/clogged, or leakage. An
electrical problem usually causes one or both of injectors
to stop functioning. Several methods may be used to
check if injectors are operating.
1. With engine running at idle, listen for a buzzing or
clicking sound.
2. Disconnect electrical connector from an injector and
listen for a change in idle performance (only running
on one cylinder) or a change in injector noise or
vibration.
If an injector is not operating, it can indicate either a bad
injector, or a wiring/electrical connection problem. Check
as follows:
1. Disconnect electrical connector from both injectors.
Plug a 12 volt noid light into one connector.
2. Make sure all safety switch requirements are met.
Crank engine and check for fl ashing of test light.
Turn key OFF for at least 10 seconds between tests
to allow ECU to go to sleep and reawake. Repeat
test at other connector.
a. If fl ashing occurs, use an ohmmeter (Rx1 scale)
and check resistance of each injector across two
terminals. Proper resistance is 7-9 Ω. If injector
resistance is correct, check whether connector
and injector terminals are making a good
connection. If resistance is not correct, replace
injector.
Check all electrical connections, connectors, and wiring
harness leads if resistance is incorrect.
Injector leakage is very unlikely, but in those rare
instances it can be internal (past tip of valve needle),
or external (weeping around injector O-rings). Loss of
system pressure from leakage can cause hot restart
problems and longer cranking times. To check for
leakage it will be necessary to loosen or remove blower
housing which may involve removing engine from unit.
Refer to Disassembly for removal of injector.
1. Remove manifold mounting bolts and separate
throttle body/manifold from engine leaving TPS, high
pressure fuel line, injectors and fuel line connections
intact. Discard old gaskets.
2. Position manifold assembly over an appropriate
container to capture fuel and turn key switch ON to
activate/energize lock-off valve and pressurize
system. Do not turn switch to START position.
3. If either injector exhibits leakage of more than two to
four drops per minute from tip, or shows any sign of
leakage around outer shell, turn ignition switch OFF
and replace injector as follows.
4. Depressurize fuel system.
5. Clean any dirt accumulation from sealing/mounting
area of faulty injector(s) and disconnect electrical
connector(s).
6. Pull retaining clip off top of injector(s). Remove
screw holding injector(s) from manifold.
3924 690 31 Rev. H KohlerEngines.com
Propane EFI System
7. Reverse appropriate procedures to install new
injector(s) and reassemble engine. Use new O-rings
and retaining clips any time an injector is removed
(new replacement injectors include new O-rings and
retaining clips). Lubricate O-rings lightly with clean
engine oil. Use installation tool provided with O-rings
to install new upper O-ring. Place tool into fuel
injector inlet. Place one side of O-ring into O-ring
groove and roll O-ring over tool onto fuel injector.
Torque screw securing fuel injector caps and blower
housing mounting screws to 7.3 N·m (65 in. lb.), and
intake manifold and air cleaner mounting screws to
10.5 N·m (93 in. lb.). An ECU Reset will need to be
completed.
Injector problems due to dirt or clogging are generally
unlikely due to design of injectors and high fuel pressure.
Symptoms that could be caused by dirty/clogged
injectors include rough idle, hesitation/stumbling during
acceleration, or triggering of fault codes related to fuel
delivery. Injector clogging is usually caused by a buildup
of deposits on director plate, restricting fl ow of fuel,
resulting in a poor spray pattern. Some contributing
factors to injector clogging include higher than normal
operating temperatures, short operating intervals, and
dirty, incorrect, or poor quality fuel. Cleaning of clogged
injectors is not recommended; they should be replaced.
Ignition Coil
If a coil is determined to be faulty, replacement is
necessary. An ohmmeter may be used to test wiring and
coil windings.
NOTE: Do not ground primary coil with ignition ON as
they may overheat or spark.
NOTE: Always disconnect spark plug lead from spark
plug before performing following tests.
NOTE: If ignition coil(s) are disabled and an ignition
fault is registered, system will automatically
disable corresponding fuel injector drive
signal. Fault must be corrected to ignition coil
and ECU power (switch) must be turned OFF for
10 seconds for injector signal to return. This is a
safety measure to prevent bore washing and oil
dilution.
Testing
Using an ohmmeter set on Rx1 scale, check resistance
in circuits as follows:
1. To check cylinder coil 1 (starter side), disconnect
Black connector from ECU and test between Black
pins 1 and 15. To check cylinder coil 2 (oil fi lter side),
disconnect Grey connector from ECU and test
between Grey pins 10 and 17. Wiring and coil
primary circuits are OK if readings are 0.5-0.8
2. If reading(s) are not within specifi ed range, check
and clean connections and retest.
3. If reading(s) are still not within specifi ed range, test
coils separately from main harness as follows:
a. Remove screw retaining coil to housing and
disconnect primary leads connector.
b. Connect an ohmmeter set on Rx1 scale to
primary terminals of coil. Primary resistance
should be 0.5-0.8 Ω.
c. Connect an ohmmeter set on Rx10K scale
between spark plug boot terminal and B+ primary
terminal. Secondary resistance should be 6400-
7800 Ω.
d. If secondary resistance is not within specifi ed
range, coil is faulty and needs to be replaced.
Propane EFI System
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FUEL COMPONENTS
WARNING
High Pressure Fluids can puncture skin and
cause severe injury or death.
Do not work on fuel system without proper
training or safety equipment.
Fluid puncture injuries are highly toxic and hazardous.
If an injury occurs, seek immediate medical attention.
Vaporizer/Regulator/Lock-Off
Details
F
G
H
I
E
C
D
B
K
A
E
J
E
A Brass Plug B Inlet Fitting
C
30-Micron Button
Filter
D Button Filter Gasket
E O-Ring F Nut
G Lock-Off H Lock-Off Valve Body
I Plunger J Screen
K Outlet Fitting
Ensure there is an adequate supply of fuel in tank
and that fuel valve is turned ON. Vaporizer/Regulator
is preset at factory, is not serviceable, and must be
replaced if determined to be faulty. If a regulator problem
is suspected, make certain lock-off is being activated,
all electrical connections are properly secured, fuses
are good, and a minimum of 7.0 volts is being supplied.
If required, testing of regulator and lock-off may be
conducted.
1. Relieve fuel pressure at lock-off . Shut off tank valve.
If possible, run engine in a well-ventilated area until
fuel system is empty and engine stops. If unable to
run engine, work in a well-ventilated area and
carefully loosen inlet fuel fi tting on vaporizer/
regulator, slowly venting off fuel from line. When fuel
is dispensed, retighten fi tting and remove quick
connect fi tting to allow fuel to escape from line.
Insert pressure test jumper (from Kohler EFI Service
Kit) between high pressure fuel line and fuel lock-off .
2. Turn on key switch to activate lock-off and check
system pressure on gauge. If system pressure of 26
psi ± 3 is observed, wiring, lock-off , and regulator
are working properly. Turn key switch OFF and
observe system pressure. System pressure should
not drop more than 5 psi per minute. If it does drop
more that this, a leak may be present in system and
should be investigated. If system pressure is OK,
depress valve button on tester to relieve system
pressure.
a. If pressure is too high or too low, replace
regulator.
3. If lock-off did not activate (step 2), disconnect plug
from lock-off . Connect a DC voltmeter across
terminals in plug, turn on key switch and observe if a
minimum of 7 volts is present during six second
prime process.
4. If no voltage is observed, connect red lead of meter
to red wire of plug and black lead to a good ground
while key is still ON.
5. If voltage is between 7 and 14, turn key switch OFF
and connect an ohmmeter between terminals on
lock-off to check for continuity.
a. If there was no continuity between lock-off
terminals, replace lock-off valve.
b. If voltage was below 7, test wiring harness and
battery.
6. If voltage at plug was good, and there was continuity
across lock-off terminals, reconnect plug to lock-off ,
making sure you have a good connection. Turn on
key switch and listen for lock-off to activate.
a. If lock-off clicks, repeat steps 1 and 2 to verify
correct pressure.
b. If lock-off still does not operate, replace it.
4124 690 31 Rev. H KohlerEngines.com
Propane EFI System
Regulator Maintenance
Drain Accumulated Deposits
Over time, depending on fuel quality, operating environment, and system performance, fuel deposits can accumulate
inside regulator. Perform following steps to remove any accumulated deposits.
1. Turn supply valve off , run engine out of fuel, and turn off ignition switch.
2. Disconnect and ground spark plug leads.
3. Remove brass plug from bottom of regulator and drain any accumulated deposits.
4. Inspect O-ring on plug; replace if damaged.
5. Reinstall plug and tighten securely.
Replace 30-Micron Button Filter
Remove inlet fi tting w/O-ring, button fi lter and gasket. Discard fi lter, gasket, and O-Ring. Position new gasket into
regulator, install button fi lter (large end in). Install new O-ring on inlet fi tting. Reinstall inlet fi tting and torque to 20 N·m
(177 in. lb.).
Lock-Off Assembly
1. Disconnect plug from lock-off . Remove nut and lock-off . Remove lock-off valve body and plunger. Discard all
parts.
2. Install plunger, then lock-off valve body. Torque body to 20 N·m (177 in. lb.).
3. Install lock-off assembly and nut. Torque nut to 6.5 N·m (57 in. lb.).
4. Reconnect plug to lock-off .
High Pressure Fuel Line
High pressure fuel line is mounted to intake manifold. No specifi c servicing is required unless operating conditions
indicate that it needs replacement. Thoroughly clean area around all joints and relieve any pressure before starting
any disassembly. Detach by removing two mounting screws, wire ties, and injector retaining clips.
Vacuum Reference Line
No specifi c servicing is required for vacuum line unless operating conditions indicate replacement is required. All
components are serviced individually. Abrasion sleeves on hoses should be reused or replaced when servicing
vacuum line. Please note routing and replicate after service or component replacement to prevent pinching or
abrasion of line. Only Kohler replacement parts can be used because vacuum line is specifi c to system and must be
maintained. Visit KohlerEngines.com for recommended Kohler replacement parts.
Throttle Body/Intake Manifold Assembly
NOTE: ECU Reset is required if throttle body is replaced.
Throttle body is serviced as an assembly, with throttle shaft, TPS, throttle plate, and idle speed adjusting screw
installed. Throttle shaft rotates on needle bearings (non-serviceable), capped with seals to prevent air leaks.
TROUBLESHOOTING
Troubleshooting Guide
Condition Possible Cause
Engine Starts Hard
or Fails to Start
When Cold.
Lock-off not functioning.
Faulty spark plugs.
Incorrect fuel.
Incorrect fuel pressure.
Crankshaft position sensor loose or faulty.
TPS set incorrect (ECU Reset and TPS Learn).
TPS faulty.
Engine temp sensor faulty.
Faulty coils.
Low system voltage.
Faulty injectors.
Faulty battery.
Loose or corroded connections.
Propane EFI System
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Troubleshooting Guide
Condition Possible Cause
Engine Starts Hard
or Fails to Start
When Hot.
Faulty spark plugs.
Lock-off not functioning.
Fuel pressure low.
Insuffi cient fuel delivery.
TPS set incorrect (ECU Reset and TPS Initialization).
Crankshaft position sensor loose or faulty.
TPS faulty.
Engine temp sensor faulty.
Faulty injectors.
Engine Stalls or
Idles Roughly
(cold or warm).
Faulty spark plugs.
Insuffi cient fuel delivery.
TPS set incorrect.
TPS faulty.
Faulty engine temperature sensor.
Faulty injectors.
Engine Misses,
Hesitates, or Stalls
Under Load.
Fuel injector(s), fuel fi lter, or fuel line.
Dirty air cleaner.
Insuffi cient fuel pressure or fuel delivery.
Vacuum (intake air) leak.
Improper governor setting, adjustment or operation.
TPS faulty, mounting problem or TPS Initialization Procedure incorrect.
Bad coil(s), spark plug(s), or wires.
Low Power
Faulty/malfunctioning ignition system.
Dirty air fi lter.
Insuffi cient fuel delivery or pressure.
Improper governor adjustment.
Plugged/restricted exhaust.
One injector not working.
Basic engine problem exists.
TPS faulty or mounting exists.
Throttle plate in throttle body not fully opening to WOT stop (if equipped).
4324 690 31 Rev. H KohlerEngines.com
Propane EFI System
Fault Codes
Example of Diagnostic Display
One second pause
One second pause
One second pause
One second pause
Three second pause
(0)
(0)
(7)
(6)
(1)
(1)
End Code 61
Fault
Code
0107
Diagnostic Fault Code Summary
Fault Code Connection or Failure Description
0031 Oxygen Sensor Heater Circuit Low Voltage
0032 Oxygen Sensor Heater Circuit High Voltage
0107 Manifold Absolute Pressure (MAP or TMAP) Sensor Circuit Low Voltage or Open
0108 Manifold Absolute Pressure (MAP or TMAP) Sensor Circuit High Voltage
0112 Intake Air Temperature (IAT or TMAP) Sensor Circuit Low Voltage
0113 Intake Air Temperature (IAT or TMAP) Sensor Circuit High Voltage or Open
0117 Coolant/Oil Temperature Sensor Circuit Low Voltage
0118 Coolant/Oil Temperature Sensor Circuit High Voltage or Open
0122 Throttle Position Sensor Circuit Low Voltage or Open
0123 Throttle Position Sensor Circuit High Voltage
0131 Oxygen Sensor 1 Circuit Low Voltage, or Open
0132 Oxygen Sensor 1 Circuit High Voltage
0171 Maximum Adaptation Limit Exceeded
0172 Minimum Adaptation Limit Exceeded
0174 Lean Fuel Condition at High Load (Open Loop)
0201 Injector 1 Circuit Malfunction
0202 Injector 2 Circuit Malfunction
0230 Fuel Lock-Off Circuit Low Voltage or Open
0232 Fuel Lock-Off Circuit High Voltage
0336 Crankshaft Position Sensor Noisy Signal
0337 Crankshaft Position Sensor No Signal
0351 Cylinder 1 Ignition Coil Malfunction
0352 Cylinder 2 Ignition Coil Malfunction
0562 System Voltage Low
0563 System Voltage High
61 End of Code Transmission
Propane EFI System
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ECU continuously monitors engine operation against
preset performance limits. If operation is outside limits,
ECU activates MIL, if equipped, and stores a diagnostic
code in its fault memory. If component or system
returns to proper function, ECU will turn off MIL. If MIL
stays illuminated, it warns customer a fault is currently
happening, and dealer service is required. Upon receipt,
dealer technician can access fault code(s) to help
determine what portion of system is malfunctioning.
Codes are accessed through key switch and displayed
as blinks or fl ashes of MIL. Access codes as follows:
1. Check that battery voltage is above 11 volts.
2. Start with key switch OFF.
3. Turn key switch to ON and OFF, then ON and OFF,
then ON, leaving it on in third sequence. Do not start
engine. Time between sequences must be less than
2.5 seconds.
4. MIL will blink a series of times. Number of times MIL
blinks represents a number in blink code.
5. A sequence of four digits make up a fault code.
There is a one (1) second pause between blinks of a
fault code. There is a three (3) second pause
between separate fault codes. After fault code(s) are
blinked a two digit 61 is blinked to indicate program
has completed.
a. It’s a good idea to write down codes as they
appear, as they may not be in numerical
sequence.
b. Code 61 will always be last code displayed,
indicating end of code transmission. If code 61
appears immediately, no other fault codes are
present.
After problem has been corrected, fault codes may
be cleared by following ECU Reset and TPS Learn
Procedures.
Diagnostic Fault Code Summary lists fault codes, and
what they correspond to. Diagnostic Code Summary
is a list of individual codes with an explanation of what
triggers them, what symptoms might be expected, and
probable causes.
A MIL may not be provided with engine. If equipment
manufacturer has not added a MIL to equipment, one
can be added easily for quick diagnostics. Main engine
to vehicle connection will have a tan wire which is
ground for MIL. Either incandescent or LED type bulbs
can be used for MIL as long as they do not draw more
than 0.1 amps. Bulb needs to be rated at 1.4 Watts or
less, or needs to have a total resistance of 140 Ω or
more. LEDs typically draw less than 0.03 amps. Attach
+12 volts to positive terminal of bulb and attach ground
terminal of bulb to tan wire.
Diagnostic Code Summary
Code 0031
Component: Oxygen Sensor Heater
Fault: O2S Heater Circuit Low Voltage
Condition: System voltage too low, open connection
or faulty sensor.
Conclusion: Engine Wiring Harness Related
● Pin circuit wiring or connectors.
ECU black pin 7 or broken wire.
Oxygen Sensor Related
● Sensor connector or wiring problem.
Poor system ground from ECU to engine
or battery to engine.
Code 0032
Component: Oxygen Sensor Heater
Fault: O2S Heater Circuit High Voltage
Condition: System voltage too high, shorted
connection or faulty sensor.
Conclusion: Oxygen Sensor Related
● Sensor connector or wiring problem.
● Sensor damaged.
● Pin circuit wiring or connectors at Black
7.
ECU Related
● ECU-to-harness connection problem.
Code 0107
Component: Manifold Absolute Pressure (MAP or
TMAP) Sensor
Fault: MAP or TMAP Circuit Low Voltage or
Open
Condition: Intake manifold leak, open connection or
faulty sensor.
Conclusion: MAP or TMAP Sensor Related
● Sensor malfunction.
● Vacuum leaks from loose manifold or
sensor.
Wire Harness Related
● Poor grounding or open circuit.
● Wire harness and connectors loose,
damaged or corroded.
● Pin circuit wiring or connectors at Black
10, 11 and 16.
Bad TPS Learn.
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Propane EFI System
Code 0108
Component: Manifold Absolute Pressure (MAP or
TMAP) Sensor
Fault: MAP or TMAP Circuit High Voltage
Condition: Intake manifold leak, shorted connection
or faulty sensor.
Conclusion: MAP or TMAP Sensor Related
● Sensor malfunction.
● Vacuum leaks from loose manifold or
sensor.
Wire Harness Related
● Poor grounding.
● Pin circuit wiring or connectors at Black
11.
Bad TPS Learn.
Code 0112
Component: Intake Air Temperature (IAT or TMAP)
Sensor
Fault: Intake Air Temperature (IAT or TMAP)
Sensor Circuit Low Voltage
Condition: Shorted connection, faulty sensor or
shorted wire.
Conclusion: Temperature (IAT or TMAP) Sensor
Related
● Sensor wiring or connection.
Engine Wiring Harness Related
● Pin circuits Black 10 and Black 8 may
be damaged or routed near noisy
signal (coils, alternator, etc.).
● ECU-to-harness connection problem.
Code 0113
Component: Intake Air Temperature (IAT or TMAP)
Sensor
Fault: Intake Air Temperature (IAT or TMAP)
Sensor Circuit High Voltage or Open
Condition: Shorted connection, faulty sensor, broken
wire or connection.
Conclusion: Temperature (IAT or TMAP) Sensor
Related
● Sensor wiring or connection.
Engine Wiring Harness Related
● Pin circuits ECU Black pin 10 and 8
may be damaged.
● ECU-to-harness connection problem or
broken wire.
Code 0117
Component: Coolant/Oil Sensor
Fault: Coolant/Oil Temperature Sensor Circuit
Low Voltage
Condition: Shorted connection, faulty sensor or
shorted wire.
Conclusion: Temperature Sensor Related
● Sensor wiring or connection.
Engine Wiring Harness Related
● Pin circuits Black 10 and Black 14
maybe damaged or routed near noisy
signal (coils, stator, etc.).
● ECU-to-harness connection problem.
Code 0118
Component: Coolant/Oil Sensor
Fault: Coolant/Oil Temperature Sensor Circuit
High Voltage or Open
Condition: Shorted connection, faulty sensor, open
connection or broken wire.
Conclusion: Temperature Sensor Related
● Sensor wiring or connection.
Engine Wiring Harness Related
● Pin circuits ECU Black pin 10 and 14
may be damaged.
● ECU-to-harness connection problem or
broken wire.
System Related
● Engine is operating above 176°C
(350°F) temperature sensor limit.
Propane EFI System
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Code 0122
Component: Throttle Position Sensor (TPS)
Fault: TPS Circuit Low Voltage or Open
Condition: Open connection, broken wire or faulty
sensor.
Conclusion: TPS Related
● TPS bad or worn internally.
Engine Wiring Harness Related
● Broken or shorted wire in harness.
ECU Black pin 10 to TPS pin 1.
ECU Black pin 12 to TPS pin 3.
ECU Black pin 16 to TPS pin 2.
Throttle Body Related
● Throttle shaft inside TPS worn, broken,
or damaged.
● Throttle plate loose or misaligned.
● Throttle plate bent or damaged
allowing extra airfl ow past, or restricting
movement.
ECU Related
● Circuit providing voltage or ground to
TPS damaged.
● TPS signal input circuit damaged.
Code 0123
Component: Throttle Position Sensor (TPS)
Fault: TPS Circuit High Voltage
Condition: Shorted connection or faulty sensor.
Conclusion: TPS Sensor Related
● Sensor connector or wiring.
● Sensor output aff ected or disrupted by
dirt, grease, oil, wear.
● Sensor loose on throttle body manifold.
Throttle Body Related
● Throttle shaft or bearings worn/
damaged.
Engine Wiring Harness Related
● ECU pins Black 10, 12 and 16
damaged (wiring, connectors).
● ECU pins Black 10, 12 and 16 routed
near noisy electrical signal (coils,
alternator).
● Intermittent 5 volt source from ECU
(pin Black 16).
● ECU-to-harness connection problem.
Code 0131
Component: Oxygen Sensor
Fault: O2S 1 Circuit Low Voltage
Condition: Open connection, broken wire or faulty
sensor.
Conclusion: Oxygen Sensor Related
● Sensor connector or wiring problem.
● Sensor contaminated, corroded or
damaged.
● Poor ground path.
● Pin circuit wiring or connectors.
ECU Black pin 10 or 17.
TPS Learn Procedure Incorrect
● Lean condition (check oxygen sensor
signal with VOA and see Oxygen
Sensor section).
Engine wiring harness related such as a
cut wire, broken or pinched.
Code 0132
Component: Oxygen Sensor
Fault: O2S 1 Circuit High Voltage
Condition: Shorted connection or faulty sensor.
Conclusion: Oxygen Sensor Related
● Sensor connector or wiring problem.
● Sensor contaminated or damaged.
● Poor ground path.
● Pin circuit wiring or connectors.
ECU Black pin 10 or Black pin 17.
Engine Wiring Harness Related
● Diff erence in voltage between sensed
voltage and actual sensor voltage.
● Short in wire harness.
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Propane EFI System
Code 0171
Component: Fuel System
Fault: Maximum adaptation limit exceeded
Condition: Fuel fi lters plugged, low pressure at
high pressure fuel line, TPS malfunction,
shorted connection, faulty sensor, low
fuel or wrong fuel type.
Conclusion: Oxygen Sensor Related
● Corrosion or poor connection.
● Sensor contaminated or damaged.
● Air leak into exhaust.
● Poor ground path.
● Pin circuit wiring or connectors.
ECU Black pin 10 or Black pin 17.
TPS Sensor Related
● Throttle plate position incorrect during
Learn procedure.
● TPS problem or malfunction.
Engine Wiring Harness Related
● Diff erence in voltage between sensed
voltage and actual sensor voltage.
● Problem in wiring harness.
● ECU-to-harness connection problem.
Systems Related
● Ignition (spark plug, plug wire, ignition
coil).
● Fuel (fuel type/quality, injector, fuel
pressure too low, fuel lock-off or
regulator).
● Combustion air (air cleaner dirty/
restricted, intake leak, throttle bores).
● Base engine problem (rings, valves).
● Exhaust system leak (muffl er, fl ange,
oxygen sensor mounting boss, etc.).
Code 0172
Component: Fuel System
Fault: Minimum adaptation limit exceeded
Condition: Too high pressure at high pressure fuel
line, TPS malfunction, shorted
connection, faulty sensor or regulator
failure.
Conclusion: Oxygen Sensor Related
● Sensor connector or wiring.
● Sensor contaminated or damaged.
● Poor ground path.
● Pin circuit wiring or connectors.
ECU Black pin 10 or 17.
TPS Sensor Related
● Throttle plate position incorrect during
Learn procedure.
● TPS problem or malfunction.
Engine Wiring Harness Related
● Diff erence in voltage between sensed
voltage and actual sensor voltage.
● Problem in wiring harness.
● ECU-to-harness connection problem.
Systems Related
● Ignition (spark plug, plug wire, ignition
coil).
● Fuel (fuel type/quality, injector, fuel
pressure too high, fuel regulator).
● Combustion air (air cleaner dirty/
restricted).
● Base engine problem (rings, valves).
Propane EFI System
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Code 0174
Component: Fuel System
Fault: Lean fuel condition
Condition: Fuel fi lters plugged, low pressure at high
pressure fuel line, TPS malfunction,
shorted connection or faulty sensor.
Conclusion: TPS Learn Incorrect
● Lean condition (check oxygen sensor
signal with VOA and see Oxygen
Sensor).
Engine Wiring Harness Related
● Pin circuit wiring or connectors.
ECU pin Black 10, 12, 16 and 17.
Low Fuel Pressure
● Low/empty fuel tank.
● Plugged fi lters.
● Bad regulator.
Oxygen Sensor Related
● Sensor connector or wiring problem.
● Exhaust leak.
● Poor ground.
Poor system ground from ECU to engine,
causing rich running while indicating lean.
Fuel lock-off connection. See Fuel
Components.
Code 0201
Component: Fuel Injector
Fault: Injector 1 Circuit Malfunction
Condition: Injector damaged or faulty, shorted or
open connection.
Conclusion: Injector Related
● Injector coil shorted or opened.
Engine Wiring Harness Related
● Broken or shorted wire in harness.
ECU pin Black 5.
● Wiring from Ignition.
ECU Related
● Circuit controlling injector #1 damaged.
Code 0202
Component: Fuel Injector
Fault: Injector 2 Circuit Malfunction
Condition: Injector damaged or faulty, shorted or
open connection.
Conclusion: Injector Related
● Injector coil shorted or opened.
Engine Wiring Harness Related
● Broken or shorted wire in harness.
ECU pin Black 6.
● Wiring from Ignition.
ECU Related
● Circuit controlling injector #2 damaged.
Code 0230
Component: Fuel Lock-off
Fault: Circuit Low Voltage or Open
Condition: Shorted or open connection.
Conclusion: Fuel Lock-off Related
● Fuel lock-off open or shorted internally.
Engine Wiring Harness related
● Broken or shorted wire in harness.
ECU pin Black 9 or Grey 17.
ECU Related
● ECU is damaged.
Code 0232
Component: Fuel Lock-off
Fault: Circuit High Voltage
Condition: Shorted connection.
Conclusion: Fuel Lock-off Related
● Fuel lock-off damaged internally.
Charging Output System Too High.
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Propane EFI System
Code 0336
Component: Crankshaft Position Sensor
Fault: Crankshaft Position Sensor Noisy Signal
Condition: Air gap incorrect, loose sensor, faulty/bad
battery, shorted or faulty connection,
faulty sensor or faulty sensor grounding.
Conclusion: Crankshaft Position Sensor Related
● Sensor connector or wiring.
● Sensor loose or air gap incorrect.
Crankshaft Position Sensor Wheel
Related
● Damaged teeth.
● Gap section not registering.
Engine Wiring Harness Related
● Pin circuit wiring or connectors.
ECU pin Black 4 and Black 13.
● ECU-to-harness connection problem.
Ignition System Related
● Non-resistor spark plug(s) used.
● Faulty or disconnected ignition coil or
secondary lead.
Code 0337
Component: Crankshaft Position Sensor
Fault: Crankshaft Position Sensor No Signal
Condition: Air gap incorrect, loose sensor, open or
shorted connection or faulty sensor.
Conclusion: Crankshaft Position Sensor Related
● Sensor connector or wiring.
● Sensor loose or air gap incorrect.
Crankshaft Position Sensor Wheel
Related
● Damaged teeth.
Engine Wiring Harness Related
● Pin circuit wiring or connectors.
ECU pin Black 4 or Black 13.
● ECU-to-harness connection problem.
If code is stored in fault history and starts
normally. Clear code, no other service
required.
Code 0351
Component: Ignition Coil
Fault: Cylinder 1 Ignition Coil Malfunction
Condition: Broken wire in harness (may not be
visible), shorted connection or faulty
sensor.
Conclusion: Engine Wiring Harness Related
● Connection to ignition or fuse.
● Pin circuit wiring or connectors.
● ECU pin Black 1.
● ECU-to-harness connection problem.
Ignition System Related
● Incorrect spark plug(s) used.
● Poor connection to spark plug.
Code 0352
Component: Ignition Coil
Fault: Cylinder 2 Ignition Coil Malfunction
Condition: Broken wire in harness (may not be
visible), shorted connection or faulty
sensor.
Conclusion: Engine Wiring Harness Related
● Connection to ignition or fuse.
● Pin circuit wiring or connectors.
ECU pin Grey 10.
● ECU-to-harness connection problem.
Ignition System Related
● Incorrect spark plug(s) used.
● Poor connection to spark plug.
Code 0562
Component: System Voltage
Fault: System Voltage Low
Condition: Faulty voltage regulator, bad fuse or
shorted connection.
Conclusion: Corroded Connections
Bad Stator
Bad Battery
● Low output charging system.
● Poor magnet in fl ywheel.
● Bad or missing fuse.
Code 0563
Component: System Voltage
Fault: System Voltage High
Condition: Faulty voltage regulator or shorted
connection.
Conclusion: Faulty Rectifi er-Regulator
Bad Stator.
Bad Battery.
Code 61
Component: End of Code Transmission
Propane EFI System
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Troubleshooting Flow Chart
Following fl ow chart provides an alternative method
of troubleshooting EFI system. Chart will enable you
to review entire system in about 10-15 minutes. Using
chart, accompanying diagnostic aids (listed chart), and
any signaled fault codes, you should be able to quickly
locate any problems within system.
Flow Chart Diagnostic Aids
Diagnostic Aid #1 SYSTEM POWER
(MIL does not illuminate when key is turned ON)
NOTE: MIL is installed by vehicle OEM. Twelve volt
supply to bulb will be part of vehicle wire
harness. Kohler key switch model will have MIL
on engine with 12V supply to bulb.
Conclusion
● Battery
● Main system fuse
● MIL light bulb burned out
● MIL electrical circuit problem
Pin circuits Grey 3.
● Ignition switch
● Permanent ECU power circuit problem
Pin circuit Black 18.
● Switched ECU power circuit problem
Pin circuit Black 15.
● ECU grounds
● ECU
Diagnostic Aid #2 FAULT CODES
Refer to Diagnostic Fault Code Summary.
Diagnostic Aid #3 RUN/ON
(MIL remains ON while engine is running)*
Condition
NOTE: Either incandescent or LED type bulbs can be
used for MIL as long as they do not draw more
than 0.1 amps. Bulb needs to be rated at 1.4
Watts or less, or needs to have a total resistance
of 140 Ω or more. LEDs typically draw less than
0.03 amps.
*All current fault codes will turn on MIL when engine is
running.
Diagnostic Aid #4 CRANKSHAFT POSITION SENSOR
(MIL does not turn off during cranking)
Condition
● Crankshaft position sensor
● Crankshaft position sensor circuit problem, pin circuits
Black 4 and Black 13.
● Crankshaft position sensor/toothed wheel air gap
● Toothed wheel
● Flywheel key sheared
● ECU
Diagnostic Aid #5 FUEL LOCK-OFF
(lock-off not activating)
Condition
● Main fuse
● Fuel lock-off circuit problem, pin circuits Black 9 and
Grey 17.
● Fuel lock-off
Diagnostic Aid #6 IGNITION SYSTEM
(no spark)
Condition
● Spark plug
● Plug wire
● Coil
● Coil circuit(s), pin circuits Grey 10 and Black 1.
● ECU grounds
● ECU
● Vehicle safety interlocks, ground signal on safety wire.
Diagnostic Aid #7 FUEL SYSTEM ELECTRICAL
(no fuel delivery)
Condition
● No fuel
● Air in high pressure fuel line
● Fuel valve shut OFF
● Fuel fi lter/line plugged
● Injector circuit(s), pin circuits Black 5 and Black 6
● Injector
● ECU grounds
● ECU
Diagnostic Aid #8 FUEL SYSTEM
(fuel pressure)
Low Fuel Pressure-Condition
● Low fuel/insuffi cient fuel supply
● Fuel fi lter plugged
● Fuel supply line plugged
● Pressure regulator not functioning properly.
Diagnostic Aid #9 BASIC ENGINE
(cranks but will not run)
Condition
● Refer to basic engine troubleshooting charts within
Troubleshooting.
5124 690 31 Rev. H KohlerEngines.com
Propane EFI System
EFI Diagnostic Flow Diagram
START OF TEST
KEY ON
MALFUNCTION
INDICATOR LIGHT
ON
ARE FAULT CODES
PRESENT?
NO
DOES ENGINE START?
NO
CRANK ENGINE.
DOES MIL GO OFF?
YES
KEY OFF AND KEY ON
1
.
LISTEN FOR FUEL LOCK-OFF.
DOES LOCK-OFF ACTIVATE
ON THEN OFF AFTER 4–6
SECONDS
2
?
YES
WHILE CRANKING, CHECK
IGNITION SYSTEM
SPARK?
YES
WHILE CRANKING, CHECK
INJECTOR FUEL DELIVERY.
ANY NOTABLE
INTERNAL
COMBUSTION?
YES
INSTALL IN-LINE PRESSURE
GAUGE AND KEY ON.
FUEL PRESSURE
IN SPECIFICATION?
NO
YES
YES MIL GOES OFF?
YES
NO
NO
NO
NO
NO
YES
REFER TO DIAGNOSTIC AID #1
SYSTEM POWER
REFER TO
DIAGNOSTIC FAULT CODE SUMMARY
CLEAR CODES
NO
REFER TO DIAGNOSTIC AID #3
RUN/ON
OPERATE AT VARIOUS SPEED/
LOAD CONDITIONS
ARE FAULT CODES
PRESENT?
NO
END OF TEST
REFER TO DIAGNOSTIC AID #4
CRANKSHAFT POSITION SENSOR
REFER TO DIAGNOSTIC AID #5
FUEL LOCK-OFF
REFER TO DIAGNOSTIC AID #6
IGNITION SYSTEM
REFER TO DIAGNOSTIC AID #7
FUEL SYSTEM ELECTRICAL
REFER TO DIAGNOSTIC AID #8
FUEL SYSTEM
REFER TO DIAGNOSTIC AID #9
BASIC ENGINE
YES
REFER TO DIAGNOSTIC
FAULT CODE SUMMARY
CLEAR CODES
PROCEED TO START OF TEST FOR RETEST
PROCEED TO START OF TEST FOR RETEST
1. After turning key to OFF, wait 10 seconds before turning to ON to allow ECU to go to sleep.
2. Fuel lock-off can be heard or felt to establish lock-off opening. Fuel lock-off will stay activated for one 4-6 second cycle when ECU wakes up
after being asleep (key ON, not cranking).
24 690 31 Rev. HKohlerEngines.com52
Lubrication System
This engine uses a full pressure lubrication system which delivers oil under pressure to crankshaft, camshaft,
connecting rod bearing surfaces, and hydraulic valve lifters.
A high-effi ciency gerotor oil pump maintains high oil fl ow and oil pressure, even at low speeds and high operating
temperatures. A pressure relief valve limits maximum pressure of system. Oil pan must be removed to service oil
pickup, pressure relief valve, and oil pump.
Lubrication Components
D
C
A
F
E
B
G
A Oil Sentry
TM
B
Oil Pressure
Switch
C Oil Fill/Dipstick D Oil Fill Tube E Oil Cooler
F Oil Filter G Back Side
OIL RECOMMENDATIONS
Refer to Maintenance.
CHECK OIL LEVEL
NOTE: To prevent extensive engine wear or damage,
never run engine with oil level below or above
operating range indicator on dipstick.
Ensure engine is cool and level. Clean oil fi ll/dipstick
areas of any debris.
1. Remove dipstick; wipe oil off .
2. Reinsert dipstick into tube; rest cap on tube, do not
thread cap onto tube.
3. Remove dipstick; check oil level. Level should be at
top of indicator on dipstick.
4. If oil is low on indicator, add oil up to top of indicator
mark.
5. Reinstall and secure dipstick.
CHANGE OIL AND FILTER
Change oil while engine is warm.
1. Clean area around oil fi ll cap/dipstick and drain plug.
Remove drain plug and oil fi ll cap/dipstick. Allow oil
to drain completely.
2. Clean area around oil fi lter. Place a container under
fi lter to catch any oil and remove fi lter. Wipe off
mounting surface. Reinstall drain plug. Torque to
13.6 N·m (10 ft. lb.).
3. Place new fi lter in shallow pan with open end up. Fill
with new oil until oil reaches bottom of threads. Allow
2 minutes for oil to be absorbed by fi lter material.
4. Apply a thin fi lm of clean oil to rubber gasket on new
fi lter.
5. Refer to instructions on oil fi lter for proper
installation.
6. Fill crankcase with new oil. Level should be at top of
indicator on dipstick.
Lubrication System
5324 690 31 Rev. H KohlerEngines.com
7. Reinstall oil fi ll cap/dipstick and tighten securely.
8. Start engine; check for oil leaks. Stop engine; correct
leaks. Recheck oil level.
9. Dispose of used oil and fi lter in accordance with
local ordinances.
OIL COOLER (if equipped)
1. Clean fi ns with a brush or compressed air.
2. Remove screws securing oil cooler and tilt to clean
back side.
3. Reinstall oil cooler and secure with screws. Torque
top screw to 2.8 N·m (25 in. lb.) and lower screw to
2.3 N·m (20 in. lb.).
OIL SENTRY
™
(if equipped)
This switch is designed to prevent engine from starting
in a low oil or no oil condition. Oil Sentry
™
may not shut
down a running engine before damage occurs. In some
applications this switch may activate a warning signal.
Read your equipment manuals for more information.
Oil Sentry
™
pressure switch is installed in breather cover.
On engines not equipped with Oil Sentry
™
installation
hole is sealed with a 1/8-27 N.P.T.F. pipe plug.
Installation
1. Apply pipe sealant with Tefl on
®
(Loctite
®
PST
®
592™
Thread Sealant or equivalent) to threads of switch.
2. Install switch into tapped hole in breather cover.
3. Torque switch to 4.5 N·m (40 in. lb.).
Testing
Compressed air, a pressure regulator, pressure gauge,
and a continuity tester are required to test switch.
1. Connect continuity tester across blade terminal and
metal case of switch. With 0 psi pressure applied to
switch, tester should indicate no continuity (switch
open).
2. Gradually increase pressure to switch. As pressure
increases through range of 2.0/5.0 psi, tester should
indicate a change to continuity (switch closed).
Switch should remain closed as pressure is
increased to 90 psi maximum.
3. Gradually decrease pressure through range of
2.0/5.0 psi. Tester should indicate a change to no
continuity (switch open) down to 0 psi.
Electrical System
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24 690 31 Rev. HKohlerEngines.com
SPARK PLUGS
CAUTION
Electrical Shock can cause injury.
Do not touch wires while engine is running.
Spark Plug Component and Details
B
A
C
D
A Wire Gauge B Spark Plug
C Ground Electrode D Gap
NOTE: Do not clean spark plug in a machine using
abrasive grit. Some grit could remain in spark
plug and enter engine causing extensive wear
and damage.
Engine misfi re or starting problems are often caused
by a spark plug that has improper gap or is in poor
condition.
Engine is equipped with following spark plugs:
Gap 0.76 mm (0.030 in.)
Thread Size 14 mm
Reach 19.1 mm (3/4 in.)
Hex Size 15.9 mm (5/8 in.)
Refer to Maintenance for Repairs/Service Parts.
Service
Clean out spark plug recess. Remove plug and replace.
1. Check gap using wire feeler gauge. Adjust gap to
0.76 mm (0.030 in.).
2. Install plug into cylinder head.
3. Torque plug to 27 N·m (20 ft. lb.).
Inspection
Inspect each spark plug as it is removed from cylinder
head. Deposits on tip are an indication of general
condition of piston rings, valves, and fuel system.
Normal and fouled plugs are shown in following photos:
Normal
Plug taken from an engine operating under normal
conditions will have light tan or gray colored deposits. If
center electrode is not worn, plug can be set to proper
gap and reused.
Worn
On a worn plug, center electrode will be rounded and
gap will be greater than specifi ed gap. Replace a worn
spark plug immediately.
Wet Fouled
A wet plug is caused by excess fuel or oil in combustion
chamber. Excess fuel could be caused by a restricted air
cleaner, a fuel system problem, or operating engine with
too much choke. Oil in combustion chamber is usually
caused by a restricted air cleaner, a breather problem,
worn piston rings, or valve guides.
5524 690 31 Rev. H KohlerEngines.com
Electrical System
Carbon Fouled
Soft, sooty, black deposits indicate incomplete
combustion caused by a restricted air cleaner, over rich
settings, weak ignition, or poor compression.
Overheated
Chalky, white deposits indicate very high combustion
temperatures. This condition is usually accompanied
by excessive gap erosion. Lean settings, an intake air
leak, or incorrect spark timing are normal causes for high
combustion temperatures.
BATTERY
A 12-volt battery with 400 cold cranking amps (cca) is
generally recommended for starting in all conditions. A
smaller capacity battery is often suffi cient if an
application is started only in warmer temperatures. Refer
to following table for minimum capacities based on
anticipated ambient temperatures. Actual cold cranking
requirement depends on engine size, application, and
starting temperatures. Cranking requirements increase
as temperatures decrease and battery capacity shrinks.
Refer to equipment's operating instructions for specifi c
battery requirements.
Battery Size Recommendations
Temperature Battery Required
Above 32°F (0°C) 200 cca minimum
0°F to 32°F (-18°C to 0°C) 250 cca minimum
-5°F to 0°F (-21°C to -18°C) 300 cca minimum
-10°F (-23°C) or below 400 cca minimum
If battery charge is insuffi cient to turn over engine,
recharge battery.
Battery Maintenance
Regular maintenance is necessary to prolong battery
life.
Battery Test
To test battery, follow manufacturer's instructions.
Electrical System
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24 690 31 Rev. HKohlerEngines.com
BATTERY CHARGING SYSTEM
NOTE: Observe following guidelines to avoid damage to electrical system and components:
● Make sure battery polarity is correct. A negative (-) ground system is used.
● Disconnect rectifi er-regulator plug and/or wiring harness plug before doing any electric welding on equipment
powered by engine. Also, disconnect all other electrical accessories in common ground with engine.
● Prevent stator (AC) leads from touching or shorting while engine is running. This could damage stator.
These engines are equipped with a 20 or 25 amp regulated charging system.
20/25 Amp Regulated Charging System
C
E
F
B
A
D
A Battery B Starter C Fuse D Rectifi er-Regulator
E Connector Block F
Flywheel Stator
Assembly
Stator
Stator is mounted on crankcase behind fl ywheel. Follow procedures in Disassembly and Reassembly if stator
replacement is necessary.
Rectifi er-Regulator
NOTE: When installing rectifi er-regulator, take note of terminal markings and install plug(s) accordingly.
NOTE: Disconnect all electrical connections attached to rectifi er-regulator. Testing may be performed with rectifi er-
regulator mounted or loose. Repeat applicable test procedure 2 or 3 times to determine condition of part.
Rectifi er-regulator is mounted on blower housing. To replace, disconnect plug(s), remove mounting screws, and
ground wire or metal grounding strap.
Testing rectifi er-regulator may be performed as follows, using appropriate rectifi er-regulator tester.
To test 20/25 amp rectifi er-regulators:
1. Connect tester ground lead (with spring clamp) to body of rectifi er-regulator.
2. Connect red lead from tester to middle terminal labeled B+.
3. Connect black leads from tester to both outer AC terminals on rectifi er-regulator.
4. Plug tester into proper AC outlet/power for tester being used. Turn on power switch. POWER light should be
illuminated and one of four status lights may be lit as well. This does not represent condition of part.
5. Press TEST button until a click is heard and then release. Momentarily one of four status lights will illuminate
indicating partial condition of part.
5724 690 31 Rev. H KohlerEngines.com
Electrical System
Condition Conclusion
20/25 amp
OK (green) light comes on and stays steady. Disconnect tester black lead attached to 1 AC terminal
and reconnect it to other AC terminal. Repeat test. If OK
(green) light comes on again, part is good and may be
used.
NOTE: A fl ashing LOW light can also occur as a result of
an inadequate ground lead connection. Make
certain connection location is clean and clamp is
secure.
Other lights come on.
Rectifi er-regulator is faulty and should not be used.
Troubleshooting Guide
20/25 Amp Battery Charging System
NOTE: Always zero digital volt-ohm meter (DVOM) on each scale before testing to ensure accurate readings. Voltage
test should be made with engine running at specifi c test condition noted. Battery should be checked for state
of charge (non-operating voltage 12.5 VDC or lower, battery should be charged or replaced).
When problems occur in keeping a battery fully charged or a battery charges at a high rate, battery or charging
system may be cause of fault. Before performing any testing, battery must be fully charged.
To test charging system:
1. Visually inspect system components and wiring.
Look for damaged or loose wire connections,
including battery cables.
2. Set DVOM to DC volts, place one lead of tester on
rectifi er-regulator body and other lead to battery
negative (-) terminal. Run engine and observe volt
reading on meter. If voltage is 0.5 VDC or less
continue with testing. If voltage is higher than 0.5
VDC, inspect and repair wiring/connections as
needed (insuffi cient ground).
3. Perform these output tests for charging system using
DVOM set to DC volts.
a. With engine off and key switch in OFF position,
measure voltage at battery. If less than 12.4 VDC,
recharge battery and retest. If 12.5 VDC continue
with tests.
b. Run engine at high speed no load (greater than
3000 RPM). After running 1 minute, measure
voltage at battery.
i. If voltage increases to between 13-15 VDC,
the system is working correctly.
ii. If voltage increases to 15.5 VDC or higher,
system is overcharging. Replace rectifi er-
regulator.
iii. If voltage stays at 12.5 VDC or decreases,
charging system is NOT operating, proceed to
step 4.
4. With engine off , unplug rectifi er-regulator connector
and inspect connector terminals within connector
body and rectifi er-regulator terminals for corrosion/
arcing/damage. Repair/replace as needed. If OK,
proceed to next test.
5. Set DVOM to AC volts, place test leads to each
white stator wire. Run engine at 1200 RPM or
greater and monitor voltage.
Condition Conclusion
Voltage is 13 volts AC or
more.
Stator is OK.
Voltage is less than 13
volts AC.
Stator is faulty. Continue
with steps 6 and 7.
6. With engine off and stator unplugged from rectifi er-
regulator, check for resistance/continuity between
across stator leads (white wires).
Condition Conclusion
Resistance is 0.1/0.2
ohms.
Stator coil is OK.
Resistance is 0 ohms. Stator is shorted; replace.
Resistance is infi nity
ohms/no continuity.
Stator is open; replace.
7. With engine off and stator unplugged from rectifi er-
regulator, check for resistance/continuity from stator
leads (white wires) to ground.
Condition Conclusion
Resistance is infi nity ohms
(no continuity).
Stator is OK (not shorted
to ground).
Resistance (or continuity)
measured.
Stator leads are shorted to
ground; replace.
8. If stator tests good (steps 4-7), but system was
identifi ed in step 3 as not working, failure is likely
with rectifi er-regulator. Replace rectifi er-regulator,
retest system to confi rm repairs (step 3).
Electrical System
58
24 690 31 Rev. HKohlerEngines.com
FUSES
This engine has 3 blade type automotive fuses.
Replacement fuses must have same rating as blown
fuse. Use fuse chart below to determine correct fuse.
Wire Color Fuse Rating
2 Purple Wires 30-amp Fuse
1 Red Wire w/Black Stripe
1 Red Wire w/White Stripe
10-amp Fuse
2 Red Wires 10-amp Fuse
Fuse Replacement
1. Shut engine off and remove key.
2. Locate fuse holders.
3. Remove fuse cover and pull out fuse.
4. Inspect fuse for a solid fusible link or a broken
fusible link. Replace fuse if fusible link is broken. If
you are not sure if fusible link is broken, replace
fuse.
5. Insert fuse into fuse holder until it is seated properly.
Install fuse cover.
PCV680LE, PCV740LE Heat Sensor Switch
PCV680LE & PCV740LE engines have a heat sensor
switch on #2 cylinder. This switch will close to ground if
engine temperature increases to excessive level. Switch
is connected to a device (light, alarm horn, or both) on
equipment this engine powers, to alert operator of this
condition. Refer to equipment manufacturer's manual for
information on their device.
5924 690 31 Rev. H KohlerEngines.com
Starter System
NOTE: Do not crank engine continuously for more than 10 seconds. Allow a 60 second cool down period between
starting attempts. Failure to follow these guidelines can burn out starter motor.
NOTE: If engine develops suffi cient speed to disengage starter but does not keep running (a false start), engine
rotation must be allowed to come to a complete stop before attempting to restart engine. If starter is engaged
while fl ywheel is rotating, starter pinion and fl ywheel ring gear may clash and damage starter.
NOTE: If starter does not crank engine, shut off starter immediately. Do not make further attempts to start engine until
condition is corrected.
NOTE: Do not drop starter or strike starter frame. Doing so can damage starter.
Engines in this series use solenoid shift starters.
Troubleshooting-Starting Diffi culties
Condition Possible Cause Conclusion
Starter does not energize. Battery Check specifi c gravity of battery. If low, recharge or replace
battery as necessary.
Wiring Clean corroded connections and tighten loose connections.
Replace wires in poor condition and with frayed or broken
insulation.
Starter Switch
or Solenoid
By-pass switch or solenoid with a jumper wire. If starter cranks
normally, replace faulty components. Remove and perform
individual solenoid test procedure.
Starter energizes but turns
slowly.
Battery Check specifi c gravity of battery. If low, recharge or replace
battery as necessary.
Brushes Check for excessively dirty or worn brushes and commutator.
Clean using a coarse cloth (not emery cloth).
Replace brushes if excessively or unevenly worn.
Transmission
or
Engine
Make sure clutch or transmission is disengaged or placed
in neutral. This is especially important on equipment with
hydrostatic drive. Transmission must be exactly in neutral to
prevent resistance which could keep engine from starting.
Check for seized engine components such as bearings,
connecting rod, and piston.
Starter System
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24 690 31 Rev. HKohlerEngines.com
SOLENOID SHIFT ELECTRIC STARTERS
Solenoid Shift Starter Components
A
B
U
T
S
R
Q
P
O
N
M
L
K
J
I
H
G
F
E
D
C
A Tube B Washer
C Armature D Drive
E Stop F Retaining Ring
G Collar H Drive End Cap
I Screw J Plunger
K Spring L Lever
M Plate N Plug
O Solenoid P Frame and Field
Q Brush Holder R Nut
S
Commutator End
Plate
T Screw
U Bolt
When power is applied to starter, armature rotates. As
armature rotates, drive pinion moves out on drive shaft
splines and into mesh with fl ywheel ring gear. When
pinion reaches end of drive shaft, it rotates fl ywheel and
cranks engine.
When engine starts, fl ywheel rotates faster than starter
armature and drive pinion. This moves drive pinion out
of mesh with ring gear and into retracted position. When
power is removed from starter, armature stops rotating
and drive pinion is held in retracted position by anti-drift
spring.
Starter Disassembly
NOTE: Do not reuse old retainer.
NOTE: Do not soak armature or use solvent when
cleaning. Wipe clean using a soft cloth, or use
compressed air.
1. Remove nut and disconnect positive (+) brush lead/
bracket from solenoid terminal.
2. Remove screws securing solenoid to starter.
3. Remove retaining ring from armature shaft using
either a retaining ring pliers or snap ring removal
tool, as described in Steps 4, and 5. Do not reuse
old retainer.
4. Remove thru (larger) bolts.
5. Remove commutator end plate assembly, containing
brush holder, brushes, springs, and locking caps.
Remove thrust washer from inside commutator end.
6. Remove frame from armature and drive end cap.
7. Remove rubber grommet and backing plate from
end cap.
8. Take out drive lever and pull armature out of drive
end cap.
9. Remove thrust washer from armature shaft.
10. Push stop collar down to expose retaining ring.
11. Remove retainer from armature shaft. Save stop
collar.
12. Remove drive pinion assembly from armature.
13. Clean parts as required.
Inspection
Check drive pinion and inspect following areas:
● Pinion teeth for abnormal wear or damage.
● Surface between pinion and clutch mechanism for
nicks or irregularities which could cause seal damage.
● Check drive clutch by holding clutch housing and
rotating pinion. Pinion should rotate in only 1 direction.
Brushes and Springs
Detail
A
A Wear Limit Length
Inspect both springs and brushes for wear, fatigue, or
damage. Measure length of each brush. Minimum length
for each brush is 7.6 mm (0.300 in.). Replace brushes if
they are worn, undersize, or condition is questionable.
6124 690 31 Rev. H KohlerEngines.com
Starter System
Armature
Components and Details
A
B
A Commutator O.D. B Mica Insulation
D
E
C
C Insulation Check D Armature Coil
E Continuity Check
1. Clean and inspect commutator (outer surface). Mica
insulation must be lower than commutator bars
(undercut) to ensure proper operation of
commutator.
2. Use an ohmmeter set to Rx1 scale. Touch probes
between 2 diff erent segments of commutator, and
check for continuity. Test all segments. Continuity
must exist between all or armature is bad.
3. Check for continuity between armature coil
segments and commutator segments. There should
be no continuity. If continuity exists between any 2
armature is bad.
4. Check armature windings/insulation for shorting.
Shift Fork
Check that shift fork is complete, and pivot and contact
areas are not excessively worn, cracked, or broken.
Brush Replacement
4 brushes and springs are serviced as a set. Use a new
Kohler brush and spring kit if replacement is necessary.
1. Perform steps 1-5 in Starter Disassembly.
2. Remove screws securing brush holder assembly to
end cap (plate). Note orientation for reassembly later.
Discard old brush holder assembly.
3. Clean component parts as required.
New brushes and springs come preassembled in a
brush holder with a protective sleeve that will also
serve as an installation tool.
4. Perform steps 10-13 in Starter Reassembly
sequence. If starter has been disassembled,
installation must be done after armature, drive lever,
and frame are installed.
Starter Reassembly
NOTE: Always use a new retainer. Do not reuse old
retainers that have been removed.
NOTE: Correctly installed, center pivot section of drive
lever will be fl ush or below machined surface of
housing.
1. Apply drive lubricant to armature shaft splines. Install
drive pinion onto armature shaft.
2. Install and assemble stop collar/retainer assembly.
a. Install stop collar down onto armature shaft with
counter bore (recess) up.
b. Install a new retainer in larger (rear) groove of
armature shaft. Squeeze with a pliers to
compress it in groove.
c. Slide stop collar up and lock it into place, so
recess surrounds retainer in groove. If necessary,
rotate pinion outward on armature splines against
retainer to help seat collar around retainer.
3. Install off set thrust (stop) washer so smaller off set of
washer faces retainer/collar.
4. Apply a small amount of oil to bearing in drive end
cap, and install armature with drive pinion.
5. Lubricate fork end and center pivot of drive lever
with drive lubricant. Position fork end into space
between captured washer and rear of pinion.
6. Slide armature into drive end cap and at same time
seat drive lever into housing.
7. Install rubber grommet into matching recess of drive
end cap. Molded recesses in grommet should be
out, matching and aligned with those in end cap.
8. Install frame, with small notch forward, onto
armature and drive end cap. Align notch with
corresponding section in rubber grommet. Install
drain tube in rear cutout, if it was removed
previously.
9. Install fl at thrust washer onto commutator end of
armature shaft.
10. Starter reassembly when replacing brushes/brush
holder assembly:
a. Hold starter assembly vertically on end housing,
and carefully position assembled brush holder
assembly, with supplied protective tube, against
end of commutator/armature. Mounting screw
holes in metal clips must be up/out. Slide brush
holder assembly down into place around
commutator, and install positive (+) brush lead
grommet in cutout of frame. Protective tube may
be saved and used for future servicing.
Starter reassembly when not replacing brushes/
brush holder assembly:
a. Carefully unhook retaining caps from brush
assemblies. Do not lose springs.
Starter System
62
24 690 31 Rev. HKohlerEngines.com
b. Position brushes back in their slots so they are fl ush with I.D. of brush holder assembly. Insert brush
installation tool (with extension), or use tube described above from a prior brush installation, through brush
holder assembly, so holes in metal mounting clips are up/out.
c. Install brush springs and snap on retainer caps.
d. Hold starter assembly vertically on end housing, and carefully place tool (with extension) and assembled
original brush holder assembly onto end of armature shaft. Slide brush holder assembly down into place
around commutator, install positive (+) brush lead grommet in cutout of frame.
11. Install end cap onto armature and frame, aligning thin raised rib in end cap with corresponding slot in grommet of
positive (+) brush lead.
12. Install thru bolts and brush holder mounting screws. Torque bolts to 5.6-9.0 N·m (49-79 in. lb.) and brush holder
mounting screws to 2.5-3.3 N·m (22-29 in. lb.).
13. Hook plunger behind upper end of drive lever and install spring into solenoid. Insert mounting screws through
holes in drive end cap. Use these to hold solenoid gasket in position, then mount solenoid. Torque screws to
4.0-6.0 N·m (35-53 in. lb.).
14. Connect positive (+) brush lead/bracket to solenoid and secure with nut. Torque nut to 8-11 N·m (71-97 in. lb.). Do
not overtighten.
Solenoid Tests
NOTE: DO NOT leave 12 volt test leads connected to solenoid for any time over what is necessary for performing
each of individual tests. Internal damage to solenoid may occur.
Disconnect all leads from solenoid including positive brush lead attached to lower stud terminal. Remove mounting
hardware and separate solenoid from starter for testing.
To test solenoid pull-in coil/plunger:
Actuation
1. Use a 12 volt power supply and 2 test leads.
2. Connect 1 lead to fl at spade S/start terminal on solenoid. Momentarily connect other lead to lower large post
terminal.
When connection is made solenoid should energize (audible click) and plunger retract. Repeat test several times.
Continuity
1. Use an ohmmeter set to audible or Rx2K scale, and connect 2 ohmmeter leads to 2 large post terminals.
2. Perform solenoid pull-in coil/plunger actuation test and check for continuity. Ohmmeter should indicate continuity.
Repeat test several times.
To test solenoid hold-in coil:
Function
1. Connect a 12 volt test lead to fl at spade S/start terminal on solenoid and other lead to body or mounting surface
of solenoid.
2. Manually push plunger IN and check if coil holds plunger retracted. Do not allow test leads to remain connected to
solenoid for a prolonged period of time.
Continuity
1. Use an ohmmeter set to audible or Rx2K scale, and connect 2 ohmmeter leads to 2 large post terminals.
2. Perform preceding solenoid hold-in coil function test and check for continuity. Meter should indicate continuity.
Repeat test several times.
Condition Conclusion
Solenoid fails to activate. Replace solenoid.
No continuity is indicated.
Plunger fails to stay retracted.
WARNING
Before working on engine or equipment, disable engine as
follows: 1) Disconnect spark plug lead(s). 2) Disconnect
negative (–) battery cable from battery.
Before disconnecting negative (–) ground cable, make sure
all switches are OFF. If ON, a spark will occur at ground
cable terminal which could cause an explosion if hydrogen
gas or propane fuel vapors are present.
Accidental Starts can cause severe injury or
death.
Disconnect and ground spark plug lead(s)
before servicing.
External Engine Components
A
B
C
I
Z
U
O
M
V
J
K
L
F
G
W
N
O
H
T
X
R
S
Q
N
Y
P
D
E
A Debris Screen Guard B Debris Screen C Air Cleaner Bracket D
High Pressure Fuel
Line Assembly
E Fuel Quick Connect F
Gaseous Propane
Fuel Injector
G
MAP or TMAP
Sensor
H
Crankshaft Position
Sensor (Earlier
Design Bracket)
I Oil Cooler O-Ring J Oil Cooler K Nipple L Oil Filter
AA
Disassembly/Inspection and Service
6324 690 31 Rev. H KohlerEngines.com
Clean all parts thoroughly as engine is disassembled.
Only clean parts can be accurately inspected
and gauged for wear or damage. There are many
commercially available cleaners that will quickly remove
grease, oil, and grime from engine parts. When such a
cleaner is used, follow manufacturer’s instructions and
safety precautions carefully.
Make sure all traces of cleaner are removed before
engine is reassembled and placed into operation. Even
small amounts of these cleaners can quickly break down
lubricating properties of engine oil.
Shut off Fuel Supply/Empty System
WARNING
Explosive Fuel can cause fi res and severe
burns.
If a gaseous odor is detected, ventilate area
and contact an authorized service technician.
Propane is extremely fl ammable and is heavier than air
and tends to settle in low areas where a spark or fl ame
could ignite gas. Do not start or operate this engine
in a poorly ventilated area where leaking gas could
accumulate and endanger safety of persons in area.
To ensure personal safety, installation and repair of
propane fuel supply systems must be performed only
by qualifi ed propane system technicians. Improperly
installed and maintained propane equipment could
cause fuel supply system or other components to
malfunction, causing gas leaks.
Observe federal, state and local laws governing
propane fuel, storage, and systems.
1. Relieve fuel pressure at lock-off . Shut off tank valve. If
possible, run engine in a well-ventilated area until fuel
system is empty and engine stops. If unable to run
engine, work in a well-ventilated area and carefully
loosen inlet fuel fi tting on vaporizer/regulator, slowly
venting off fuel from line. When fuel is dispensed,
retighten fi tting and remove quick connect fi tting to
allow fuel to escape from line.
Disconnect Spark Plug Leads
NOTE: Pull on boot only, to prevent damage to spark
plug lead.
Disconnect leads from spark plugs.
Drain Oil from Crankcase and Remove Oil Filter
NOTE: Some models are equipped with an oil drain valve.
1. Remove oil fi ll cap/dipstick, and 1 oil drain plug.
2. Allow ample time for oil to drain from crankcase and oil
fi lter.
3. Remove mounting screw and oil fi ll tube.
4. Remove and discard oil fi lter.
Remove Oil Cooler
1. Use an 8 mm Allen wrench to remove oil fi lter
threaded nipple.
2. Separate fi lter adapter from oil pan, leaving oil lines
attached. Remove screws mounting oil cooler to
blower housing, then remove cooler, lines, and fi lter
adapter with O-ring, as an assembly.
Remove Muffl er (if equipped) PCV680, PCV740
NOTE: Removing oxygen sensor is not required to
remove exhaust system.
1. Remove exhaust system and attaching hardware
from engine.
2. Disconnect oxygen sensor connector from wire
harness.
Remove Muffl er PCV680LE, PCV740LE
NOTE: Removing oxygen sensor is not required to
remove exhaust system.
1. Disconnect oxygen sensor connector from wire
harness.
2. Carefully remove oxygen sensor connector from clip/
bracket.
3. Remove nuts securing muffl er to exhaust ports.
4. Remove screws securing muffl er to main support
bracket.
5. Remove muffl er, exhaust gaskets, and port liners;
discard gaskets.
6. Remove valve cover screws securing oxygen sensor
clip/bracket and main support bracket; remove
brackets.
M Ignition Coil N Barrel Baffl e O Valley Baffl e P Breather Cover
Q
Breather Cover
Gasket
R Oil Sentry
™
S
Oil Temperature
Sensor
T
Throttle Body
Assembly
U
Air Temperature
Sensor
V Dipstick Tube W Oil Fill Cap/Dipstick X Air Cleaner
Y Breather Hose Z Breather Separator AA
Crankshaft Position
Sensor (Later
Design Bracket)
Disassembly/Inspection and Service
64 24 690 31 Rev. HKohlerEngines.com
Remove Air Cleaner Assembly
Heavy Duty Air Cleaner
1. Remove nuts securing air cleaner to mounting studs.
2. Remove screws securing air cleaner assembly to
mounting bracket and remove air cleaner assembly.
Low-Profi le Air Cleaner (Optional)
1. Loosen retaining knob and remove cover.
2. Remove wing nut from element cover.
3. Remove element cover, element and precleaner.
4. Remove nuts securing base. Additional screws must
be removed from lower air cleaner support bracket.
5. Remove base.
Remove Heat Defl ectors PCV680LE, PCV740LE
B B
A
A
C
C
A Heat Defl ector B Nut
C Screw
Remove screw and nut securing each heat defl ector to
cylinder head near exhaust port.
Remove Top Mount Control Panel
1. Remove throttle control shaft nut on top of throttle
shaft and remove throttle control lever, washer, and
spring.
2. Remove screws fastening control bracket and
remove bracket from blower housing.
3. Remove lower throttle control bracket from cylinder
head.
Remove External Governor Controls
NOTE: To aid in reassembly, mark hole locations of
governor spring, throttle linkage spring, throttle
linkage, before removing them from governor lever.
1. Disconnect governor spring attached to governor lever.
Note/mark hole location for reassembly.
2. Note/mark hole location, then disconnect throttle
linkage spring from governor lever. Remove throttle
linkage bushing and throttle linkage from governor
lever. Note/mark hole location for reassembly.
3. Loosen nut and remove governor lever from cross shaft.
Disassembly/Inspection and Service
6524 690 31 Rev. H KohlerEngines.com
External Governor Controls
A
N
C
E
G
F
D
J
I
L
H
K
M
B
A
Throttle Control Shaft
Nut
B Throttle Control Shaft C Throttle Control Lever D Washer
E Spring F Control Bracket G
Throttle Control
Bracket (lower)
H Governor Spring
I Governor Lever J
Throttle Linkage
Spring
K Bushing L Throttle Linkage
M Nut N Governor Cross Shaft
Disassembly/Inspection and Service
66 24 690 31 Rev. HKohlerEngines.com
Vaporizer/Regulator/Lock-Off Assembly
WARNING
Propane is extremely fl ammable and is heavier than air and
tends to settle in low areas where a spark or fl ame could
ignite gas. Do not start or operate this engine in a poorly
ventilated area where leaking gas could accumulate and
endanger safety of persons in area.
To ensure personal safety, installation and repair of propane
fuel supply systems must be performed only by qualifi ed
propane system technicians. Improperly installed and
maintained propane equipment could cause fuel supply
system or other components to malfunction, causing gas
leaks.
Observe federal, state and local laws governing propane
fuel, storage, and systems.
Explosive Fuel can cause fi res and severe
burns.
If a gaseous odor is detected, ventilate area
and contact an authorized service technician.
Remove Vaporizer/Regulator/Lock-Off
A
G
B
C
F
E
D
H
A Vacuum Line B Vaporizer/Regulator C Inlet Fitting D Lock-Off Assembly
E Propane Fuel Filter F Bracket G Outlet Fitting H Oetiker Clamp
1. Disconnect electrical plug from lock-off .
2. Disconnect vacuum line from front of vaporizer/
regulator.
3. Loosen nut on center back of vaporizer/regulator.
Keep all fuel lines connected, then lift up on
regulator so nut comes through key hole slot in
bracket, removing vaporizer/regulator from bracket
(keeping fuel lines, propane fuel fi lter assembled).
Separate parts only if additional service is required.
Do not cut Oetiker clamps unless fuel lines and/or
propane fuel fi lter are being replaced.
4. Remove screws securing regulator bracket to
crankcase.
Remove Throttle Body
1. On earlier engines with separate intake air
temperature (IAT) and MAP sensors, disconnect IAT
sensor from throttle body. Sensor can stay in throttle
body unless it is being replaced.
2. Disconnect breather tube from throttle body.
3. Disconnect throttle position sensor connector.
4. Disconnect vent hose from throttle body.
5. Remove screws securing air cleaner bracket, take
off bracket and slide throttle body (with linkage and
spring connected) off intake manifold.
Disassembly/Inspection and Service
6724 690 31 Rev. H KohlerEngines.com
ECU
Remove Electronic Control Unit (ECU)
B
A
C
A
Electronic Control
Unit (ECU)
B ECU Bracket
C Starter
1. Remove screws securing ECU to bracket.
2. Disconnect Black and Grey electrical connectors
from ECU.
Remove Electronic Control Unit Bracket and
Electric Starter Motor
1. Disconnect leads from starter.
2. Remove screws, ECU bracket, and starter assembly.
Remove Oil Separator and Hardware
Remove screws securing oil separator assembly, pulling
assembly out and away from valve cover.
Remove Guard and Debris Screen
NOTE: Fan will be loose, but cannot be removed until
after blower housing is removed.
1. Remove screws securing guard to blower housing
and remove guard and spacers.
2. Remove screws securing metal screen and remove
screen.
3. Remove support ring, spacers, and washers paying
attention to curvature of spring washers between
spacers and fan.
Remove Outer Barrel Baffl es and Blower Housing
1. Disconnect plug from rectifi er-regulator.
2. Remove silver or green plated rectifi er-regulator
ground strap/ground lead screw fastened to
crankcase. Rectifi er-regulator does not have to be
detached from blower housing.
3. Disconnect 3 fuse connectors on outer baffl e and
allow them to hang.
4. Remove screws securing outer barrel baffl es. Note
location of any lifting strap and position of short
screws for reassembly. Coil and any hoses may
remain attached to baffl e after being unplugged or
disconnected.
5. Remove outer barrel baffl es.
6. Remove remaining screws securing blower housing.
Remove blower housing.
Remove Oil Sentry
™
(If Equipped)
NOTE: This is optional. Removing Oil Sentry
™
is not
required to remove breather cover.
1. Disconnect lead from Oil Sentry
™
switch.
2. Remove Oil Sentry
™
switch from breather cover.
Remove Oil Temperature Sensor
NOTE: Unless oil temperature sensor is damaged or
malfunctioning, disassembly from breather cover
is unnecessary.
1. Disconnect lead from oil temperature sensor.
2. Remove oil temperature sensor from breather cover.
Remove Inner Baffl es and Breather Cover
NOTE: Removing oil temperature sensor is not required
to remove breather cover or inner baffl es.
1. Remove screws securing inner baffl es to crankcase.
2. Remove inner (valley) baffl es.
3. Disconnect and remove oil temperature sensor.
4. Remove remaining screws from breather cover.
5. Pry under protruding edge of breather cover with a
screwdriver to break gasket seal. Do not pry on
sealing surfaces as it could cause damage resulting
in leaks.
6. Remove breather cover and gasket.
Remove Crankshaft Position Sensor
1. Remove screws securing crankshaft position sensor
bracket.
2. Disconnect electrical connector from crankshaft
position sensor.
Remove Manifold Absolute Pressure (MAP) Sensor
or Temperature/Manifold Absolute Pressure (TMAP)
Sensor
1. With a screwdriver, slide locking tab on electrical
connector.
2. Detach connector.
3. Remove screw and pull MAP or TMAP sensor out of
intake manifold.
Remove Fuel Injectors
1. Disconnect electrical connector.
2. Remove screw and pull injector out of intake
manifold for each injector.
3. When removed, pull metal retaining clip connecting
fuel injector to fuel injector cap. There may be some
fuel left in line. Any spilled fuel must be cleaned up
immediately.
Disassembly/Inspection and Service
68 24 690 31 Rev. HKohlerEngines.com
Cylinder Head Components
A
B
C
D
E
F
H
I
J
K
G
N
P
O
Q
L
M
S
R
Style AStyle B
T
A Valve Cover B Valve Cover Gasket C Hex Flange Screw D Rocker Arm Pivot
E Rocker Arm F Push Rod G Hydraulic Lifter H Valve Cap
I Valve Keeper J Valve Spring K Valve Seal L
Valve Spring
Retainer
M Spark Plug N Cylinder Head O
Cylinder Head
Gasket
P Valve
Q Dowel Pin R
Hydraulic Lifter
Style A (Ribbed)
S
Hydraulic Lifter
Style B (Smooth)
T
Heat Sensor Switch
(PCV680LE,
PCV740LE)
Remove Intake Manifold
1. Remove screw securing a ring terminal which is part
of wiring harness.
2. Remove screws securing intake manifold to cylinder
heads. Note which screws hold wiring clamp.
3. Unclasp wiring harness from clip using a
screwdriver.
4. Remove intake manifold and intake manifold
gaskets.
5. Leave high pressure fuel line and wiring harness
attached to manifold.
Disconnect Heat Sensor Switch PCV680LE,
PCV740LE
NOTE: Heat sensor switch is located on #2 cylinder
head.
Disconnect lead from heat sensor switch terminal.
Disassembly/Inspection and Service
6924 690 31 Rev. H KohlerEngines.com
Remove Valve Covers
NOTE: PCV680LE and PCV740LE engines have a
main support bracket secured with inner valve
cover screws. Main support bracket was
removed after muffl er.
1. Remove screws securing each valve cover. Note
valve cover diff erences for proper location in
reassembly. Ensure any brackets removed are
reassembled in same location.
2. Covers should lift off without prying.
Remove Spark Plugs
Remove spark plug from each cylinder head.
Remove Cylinder Heads and Hydraulic Lifters
NOTE: PCV680LE and PCV740LE engines have a heat
sensor switch secured on #2 cylinder head. Take
note of switch position before removing head
fasteners.
1. Remove nuts and washers securing each cylinder
head. Discard nuts and washers once removed. Do
not reuse. Studs should only be removed if damaged
or if cylinder reconditioning is necessary. Once
removed, they must be replaced.
2. Mark location of push rods as either intake or
exhaust and cylinder 1 or 2. Push rods should
always be reinstalled in same positions.
3. Carefully remove push rods, cylinder heads, and
head gaskets.
4. Remove lifters from lifter bores. Use a hydraulic lifter
tool. Do not use a magnet to remove lifters. Mark
lifters by location, as either intake or exhaust, and
cylinder 1 or 2. Hydraulic lifters should always be
reinstalled in same position.
Inspection
Check base surface of hydraulic lifters for wear or
damage. If lifters need to be replaced, apply a liberal
coating of Kohler lubricant (see Tools and Aids) to base
of each new lifter before it is installed.
Bleeding Lifters Style A (Ribbed)
To prevent a possible bent push rod or broken rocker
arm, it is important to bleed any excess oil out of lifters
before they are installed.
1. Cut a 50-75 mm (2-3 in.) piece from end of an old
push rod and chuck it in a drill press.
2. Lay a rag or shop towel on table of drill press and
place lifter, open end up, on towel.
3. Lower chucked push rod until it contacts plunger in
lifter. Slowly pump plunger 2 or 3 times to force oil
out of feed hole in side of lifter.
Bleeding Lifters Style B (Smooth)
To prevent a possible bent push rod or broken rocker
arm, it is important to bleed any excess oil out of lifters
before they are installed.
1. Lay a rag or shop towel on table of drill press. Place
an 8 mm (5/16 in.) socket on towel with well end up,
then place open end of lifter on socket. Ensure
socket does not contact lifter ball surface.
2. Place some material, such as wood, plastic, or
aluminum, on top of lifter to protect lifter fi nish.
3. Lower drill press chuck until it contacts material on
lifter. Slowly pump lifter 2 or 3 times to force oil out of
feed hole in side of lifter.
Disassemble Cylinder Heads
NOTE: These engines use valve stem seals on intake
and exhaust valves. Use a new seal whenever
valve is removed or if seal is deteriorated or
damaged in any way. Never reuse an old seal.
1. Remove screws, rocker arm pivots and rocker arms
from cylinder head. Note screw color for reassembly.
2. Compress valve springs using a valve spring
compressor.
3. Once valve spring is compressed, remove valve
spring keepers, then remove following items.
● Valve spring retainers
● Valve springs
● Valve spring caps
● Intake and exhaust valve (mark position)
● Valve stem seals (intake and exhaust)
4. Repeat above procedure for other cylinder head. Do
not interchange parts from one cylinder head to
other.
Disassembly/Inspection and Service
70 24 690 31 Rev. HKohlerEngines.com
Inspection and Service
Valve Details
EXHAUST VALVE INTAKE VALVE
EXHAUST
INSERT
INTAKE
INSERT
H
H
G
G
E
E
F
F
A
A
C
D
D
B
B
Dimension Intake Exhaust
A Seat Angle 89° 89°
B Insert O.D. 36.987/37.013 mm (1.4562/1.4572 in.) 32.987/33.013 mm (1.2987/1.2997 in.)
C Guide Depth 4 mm (0.1575 in.) 6.5 mm (0.2559 in.)
D Guide I.D. 7.038/7.058 mm (0.2771/0.2779 in.) 7.038/7.058 mm (0.2771/0.2779 in.)
E Valve Head Diameter 33.37/33.63 mm (1.3138/1.3240 in.) 29.37/29.63 mm (1.1563/1.1665 in.)
F Valve Face Angle 45° 45°
G Valve Margin (Min.) 1.5 mm (0.0591 in.) 1.5 mm (0.0591 in.)
H Valve Stem Diameter 6.982/7.000 mm (0.2749/0.2756 in.) 6.970/6.988 mm (0.2744/0.2751 in.)
Disassembly/Inspection and Service
7124 690 31 Rev. H KohlerEngines.com
After cleaning, check fl atness of cylinder head and
corresponding top surface of crankcase, using a surface
plate or precision straight edge and feeler gauge.
Maximum allowable out of fl atness is 0.076 mm (0.003
in.).
Carefully inspect valve mechanism parts. Inspect valve
springs and related hardware for excessive wear or
distortion. Check valves and valve seat area or inserts
for evidence of deep pitting, cracks, or distortion. Check
clearance of valve stems in guides. See valve details
and specifi cations.
Hard starting or loss of power accompanied by high
fuel consumption may be symptoms of faulty valves.
Although these symptoms could also be attributed to
worn rings, remove and check valves fi rst. After removal,
clean valve heads, faces, and stems with a power wire
brush. Then, carefully inspect each valve for defects
such as a warped head, excessive corrosion, or a worn
stem end. Replace valves found to be in bad condition.
Valve Guides
If a valve guide is worn beyond specifi cations, it will not
guide valve in a straight line. This may result in burnt
valve faces or seats, loss of compression, and excessive
oil consumption.
To check valve guide-to-valve stem clearance,
thoroughly clean valve guide and, using a split-ball
gauge, measure inside diameter of guide. Then, using
an outside micrometer, measure diameter of valve stem
at several points on stem where it moves in valve guide.
Use largest stem diameter to calculate clearance by
subtracting stem diameter from guide diameter. If intake
clearance exceeds 0.038/0.076 mm (0.0015/0.0030
in.) or exhaust clearance exceeds 0.050/0.088 mm
(0.0020/0.0035 in.), determine whether valve stem or
guide is responsible for excessive clearance.
Maximum (I.D.) wear on intake valve guide is 7.134 mm
(0.2809 in.) while 7.159 mm (0.2819 in.) is maximum
allowed on exhaust guide. Guides are not removable but
can be reamed 0.25 mm (0.010 in.) oversize. Valves with
0.25 mm oversize stems must then be used.
If guides are within limits but valve stems are worn
beyond limits, install new valves.
Valve Seat Inserts
Hardened steel alloy intake and exhaust valve seat
inserts are press fi tted into cylinder head. Inserts are
not replaceable but can be reconditioned if not too badly
pitted or distorted. If cracked or badly warped, cylinder
head should be replaced.
Recondition valve seat inserts following instructions
provided with valve seat cutter being used. Final cut
should be made with an 89° cutter as specifi ed for
valve seat angle. Cutting proper 45° valve face angle
as specifi ed, and proper valve seat angle (44.5°, half of
full 89° angle), will achieve desired 0.5° (1.0° full cut)
interference angle where maximum pressure occurs on
outside diameters of valve face and seat.
Lapping Valves
NOTE: Exhaust valves that are black in color cannot be
ground and do not require lapping.
Reground or new valves must be lapped in, to provide
proper fi t. Use a hand valve grinder with a suction cup
for fi nal lapping. Lightly coat valve face with a fi ne grade
of grinding compound, then rotate valve on its seat with
grinder. Continue grinding until a smooth surface is
obtained on seat and on valve face. Thoroughly clean
cylinder head in soap and hot water to remove all traces
of grinding compound. After drying cylinder head, apply
a light coating of SAE 10 oil to prevent rusting.
Valve Stem Seal
These engines use valve stem seals on intake and
exhaust valves. Always use a new seal when valves
are removed from cylinder head. Seals should also be
replaced if deteriorated or damaged in any way. Never
reuse an old seal.
Disassembly/Inspection and Service
72 24 690 31 Rev. HKohlerEngines.com
NOTE: Always use a fl ywheel puller to remove fl ywheel
from crankshaft. Do not strike crankshaft or
fl ywheel, as these parts could become cracked
or damaged. Striking puller or crankshaft can
cause crank gear to move, aff ecting crankshaft
endplay.
1. Remove fan (screws were removed earlier with
debris screen).
2. Use a fl ywheel strap wrench or holding tool (see
Tools and Aids) to hold fl ywheel and loosen screw
securing fl ywheel to crankshaft.
3. Remove screw and washer.
4. Use a puller to remove fl ywheel from crankshaft.
5. Remove woodruff key.
Inspection
Inspect fl ywheel for cracks and fl ywheel keyway for
damage. Replace fl ywheel if it is cracked. Replace
fl ywheel, crankshaft, and key if fl ywheel key is sheared
or keyway is damaged.
Inspect ring gear for cracks or damage. Kohler does not
provide ring gear as a serviceable part. Replace fl ywheel
if ring gear is damaged.
Remove Stator and Backing Plate
1. Remove screws securing backing plate. Remove
backing plate.
2. Remove screws and stator. Note position/routing of
stator lead.
Flywheel Components
A
B
D
C
A Flywheel Fan B Flywheel
C Stator D Backing Plate
NOTE: Always use a fl ywheel strap wrench or holding
tool to hold fl ywheel when loosening or
tightening fl ywheel screw. Do not use any type
of bar or wedge to hold fl ywheel. Use of such
tools could cause fl ywheel to become cracked or
damaged.
Disassembly/Inspection and Service
7324 690 31 Rev. H KohlerEngines.com
Q
Governor Cross
Shaft
R Crankcase
S
Oil Pump Assembly
(Style B)
T
Outer Gerotor Gear
(Style B)
U
Oil Pump Cover
O-ring (Style B)
V Spring (Style B)
W Ball (Style B) X
Oil Screen
(Style B)
Y Oil Pan (Style B)
Remove Oil Pan Assembly
1. Remove screws securing oil pan to crankcase.
2. Locate splitting tabs cast into perimeter of closure
plate. Insert drive end of a 1/2 in. breaker bar
between splitting tab and crankcase and turn it to
loosen seal. Do not pry on sealing surfaces as this
can cause leaks.
Inspection
Inspect oil seal in oil pan and remove it if it is worn
or damaged. Refer to Install Oil Pan Oil Seal in
Reassembly for new oil seal installation.
Inspect main bearing surface for wear or damage (refer
to Specifi cations). Replace oil pan assembly if required.
Governor Gear Assembly
Governor Shaft Press Depth Details
C
B
A
A Gear Shaft
B 19.40 mm (0.7638 in.)
C 34.0 mm (1.3386 in.) 33.5 mm (1.3189 in.)
Governor gear assembly is located inside oil pan.
If service is required, continue with Inspection,
Disassembly, and Reassembly.
Inspection
Inspect governor gear teeth. Replace gear if it is worn,
chipped, or if any teeth are missing. Inspect governor
weights. They should move freely in governor gear.
Crankcase Components
C
D
E
B
F
G
P
I
J
K
L
M
N
O
Q
R
A
H
Y
S
T
U
W
V
X
A Oil Pan Seal B Oil Pan (Style A)
C
Gerotor Gears
(Style A)
D
Oil Pump Assembly
(Style A)
E Governor Shaft F Governor Washer
G Governor Gear H Governor Cup
I Crankshaft J Connecting Rod
K Piston L Piston Pin
M
Piston Pin Retainer
Clip
N Piston Rings
O Camshaft P Oil Pan Gasket
Disassembly/Inspection and Service
74 24 690 31 Rev. HKohlerEngines.com
Disassembly
NOTE: Governor gear is held onto shaft by small
molded tabs in gear. When gear is removed from
shaft, these tabs are destroyed and gear must
be replaced. Therefore, remove gear only if
absolutely necessary.
Governor gear must be replaced once it is removed from
oil pan.
1. Remove regulating pin and governor gear assembly.
2. Remove locking tab thrust washer located under
governor gear assembly.
3. Carefully inspect governor gear shaft and replace it
only if it is damaged. After removing damaged shaft,
press or lightly tap replacement shaft into oil pan to
depth shown.
Reassembly
1. Install locking tab thrust washer on governor gear
shaft with tab down.
2. Position regulating pin within governor gear/fl yweight
assembly and slide both onto governor shaft.
Oil Pump Assembly (Style A)
Oil Pump (Style A) Torque Sequence
1
2
Oil pump is mounted inside oil pan. If service is required,
continue with Disassembly, Inspection, and Reassembly.
Disassembly
1. Remove screws.
2. Remove oil pump assembly from oil pan.
3. Remove oil pump rotor. Unhook locking clip, and
care fully pull it free from oil pump housing.
Relief valve is a one-piece style, staked to oil pump
housing. Removal should not be attempted, nor is
internal servicing possible. If a problem with relief
valve is encountered, oil pump should be replaced.
Inspection
Inspect oil pump housing, gear, and rotors for nicks,
burrs, wear, or any visible damage. If any parts are worn
or damaged, replace oil pump.
Reassembly
1. Install oil pickup to oil pump body. Lubricate O-ring
with oil and make sure it remains in groove as
pickup is being installed.
2. Install rotor.
3. Install oil pump body to oil pan and secure with
screws. Torque screws as follows:
a. Install fastener into location 1 and lightly tighten
to position pump.
b. Install fastener into location 2 and fully torque to
recommended value.
c. Torque fastener in location 1 to recommended
value.
First Time Installation: 10.7 N·m (95 in. lb.)
All Reinstallations: 6.7 N·m (60 in. lb.)
4. After torquing, rotate gear and check for freedom of
movement. Make sure there is no binding. If binding
occurs, loosen screws, reposition pump, retorque
screws and recheck movement.
Oil Pump Assembly (Style B)
Oil pump is mounted inside oil pan. If service is required,
continue with Disassembly, Inspection, and Reassembly.
Disassembly
1. Remove screws.
2. Lift oil pump assembly from oil pan. Remove outer
gerotor gear from oil pan.
3. Ensure ball and spring remain installed in pressure
relief hole of oil pan. If ball and spring fall out of
pressure relief hole, see reassembly for correct
installation.
4. Remove oil pump cover O-ring from groove in oil
pan.
Inspection
Inspect oil pump housing, gear, and rotors for nicks,
burrs, wear, or any visible damage. Inspect oil pump
cover O-ring for cuts, nicks, or any visible damage. If any
parts are worn or damaged, replace oil pump assembly
and/or O-ring. Check oil pickup screen for damage or
restriction, replace if necessary.
Reassembly
1. Lubricate outer gerotor gear with oil. Install outer
gerotor gear through shaft of oil pump, around inner
gerotor gear. Matching molding dots on inner and
outer gerotor gears is not necessary and will not
aff ect oil pump effi ciency.
2. Reinstall ball, then spring into pressure relief hole in
oil pan.
3. Reinstall O-ring into groove in oil pan; make sure it is
fully seated in groove.
4. Install oil pump inserting center shaft into
corresponding recess in oil pan. Apply consistent
downward pressure to oil pump cover, compressing
oil pressure relief spring and start screws. Secure oil
pump by torquing screws (in no specifi c sequence)
to 9.0 N·m (80 in. lb.).
5. After torquing, rotate gear and check for freedom of
movement. Make sure there is no binding. If binding
occurs, loosen screws, reposition pump, retorque
screws and recheck movement.
Disassembly/Inspection and Service
7524 690 31 Rev. H KohlerEngines.com
Remove Camshaft
Remove camshaft.
Inspection and Service
NOTE: To prevent repeat failures, camshaft and
crankshaft should always be replaced as a set.
Check lobes of camshaft for wear or damage. See
Specifi cations for minimum lift tolerances. Measurement
must be performed while valve train is still assembled.
Inspect cam gear for badly worn, chipped or missing
teeth. Replacement of camshaft will be necessary if any
of these conditions exist.
Remove Governor Cross Shaft
1. Remove retainer and nylon washer, from governor
cross shaft.
2. Remove cross shaft through inside of crankcase.
Governor Cross Shaft Oil Seal
Cross Shaft Oil Seal Details
B
A
A 2.0 mm (0.0787 in.)
B Governor Cross Shaft Seal
If governor cross shaft seal is damaged and/or leaks,
replace it using these following procedures.
Remove oil seal from crankcase and replace it with a
new one. Install new seal to depth shown using a seal
installer.
Remove Connecting Rods with Pistons and Rings
NOTE: If a carbon ridge is present at top of either
cylinder bore, use a ridge reamer tool to remove
it before attempting to remove piston.
NOTE: Cylinders are numbered on crankcase. Use
numbers to mark each end cap, connecting rod
and piston for reassembly. Do not mix end caps
and connecting rods.
1. Remove screws securing closest connecting rod end
cap. Remove end cap.
2. Carefully remove connecting rod and piston
assembly from cylinder bore.
3. Repeat above procedure for other connecting rod
and piston assembly.
4. Remove piston pin from piston for inspection. Use a
small screwdriver to pry pin retainer out of groove.
Inspection
Piston and Rings Components and Details
A
B
D
E
C
F
A Piston B
Top Compression
Ring
C
Middle Compression
Ring
D Rails
E Expander F
Oil Control Ring
(3 Piece)
Scuffi ng and scoring of pistons and cylinder walls occurs
when internal engine temperatures approach welding
point of piston. Temperatures high enough to do this are
created by friction, which is usually attributed to improper
lubrication and/or overheating of engine.
Normally, very little wear takes place in piston boss-
piston pin area. If original piston and connecting rod can
be reused after new rings are installed, original pin can
also be reused but new piston pin retainers are required.
Piston pin is included as part of piston assembly – if pin
boss in piston or pin are worn or damaged, a new piston
assembly is required.
Disassembly/Inspection and Service
76 24 690 31 Rev. HKohlerEngines.com
Ring failure is usually indicated by excessive oil
consumption and blue exhaust smoke. When rings fail,
oil is allowed to enter combustion chamber where it is
burned along with fuel. High oil consumption can also
occur when piston ring end gap is incorrect because
ring cannot properly conform to cylinder wall under this
condition. Oil control is also lost when ring gaps are not
staggered during installation.
When cylinder temperatures get too high, lacquer and
varnish collect on pistons causing rings to stick, which
results in rapid wear. A worn ring usually takes on a
shiny or bright appearance.
Scratches on rings and pistons are caused by abrasive
material such as carbon, dirt, or pieces of hard metal.
Detonation damage occurs when a portion of fuel charge
ignites spontaneously from heat and pressure shortly
after ignition. This creates 2 fl ame fronts which meet and
explode to create extreme hammering pressures on a
specifi c area of piston. Detonation generally occurs from
using low octane fuels.
Preignition or ignition of fuel charge before timed spark
can cause damage similar to detonation. Preignition
damage is often more severe than detonation damage.
Preignition is caused by a hot spot in combustion
chamber from sources such as glowing carbon deposits,
blocked cooling fi ns, an improperly seated valve, or
wrong spark plug(s).
Replacement pistons are available in STD bore size, and
in 0.25 mm (0.010 in.), and 0.50 mm (0.020 in.) oversize.
Replacement pistons include new piston ring sets and
new piston pins.
Replacement ring sets are also available separately
for STD, 0.25 mm (0.010 in.), and 0.50 mm (0.020 in.)
oversize pistons. Always use new piston rings when
installing pistons. Never use old rings.
Some important points to remember when servicing
piston rings:
1. Cylinder bore must be deglazed before service ring
sets are used.
2. If cylinder bore does not need reboring and if old
piston is within wear limits and free of score or scuff
marks, old piston may be reused.
3. Remove old rings and clean up grooves. Never
reuse old rings.
4. Before installing new rings on piston, place top 2
rings, each in turn, in its running area in cylinder
bore and check end gap. Compare ring gap to
tolerance listed in Specifi cations.
5. After installing new compression (top and middle)
rings on piston, check piston-to-ring side clearance.
Compare clearance to tolerance listed in
Specifi cations. If side clearance is greater than
specifi ed, a new piston must be used.
Install New Piston Rings
Piston Ring Orientation
10°
10°
F
A
B
C
D
E
A
Top Oil Ring Rail
Gap
B
Bottom Oil Ring Rail
Gap
C
Intermediate Ring
Gap
D
Oil Ring Expander
Gap
E Top Ring Gap F FLY Stamp
NOTE: Rings must be installed correctly. Ring
installation instructions are usually included with
new ring sets. Follow instructions carefully. Use
a piston ring expander to install rings. Install
bottom (oil control) ring fi rst and top
compression ring last.
To install new piston rings, proceed as follows:
1. Oil control ring (bottom groove): Install expander and
then rails. Make sure ends of expander are not
overlapped.
2. Middle compression ring (center groove): Install
center ring using a piston ring installation tool. Make
sure identifi cation mark is up or colored dye stripe
(if contained), is to left of end gap.
3. Top compression ring (top groove): Install top ring
using a piston ring expander. Make sure
identifi cation mark is up or colored dye stripe
(if contained), is to left of end gap.
Disassembly/Inspection and Service
7724 690 31 Rev. H KohlerEngines.com
Connecting Rods
Off set, stepped-cap connecting rods are used in all
these engines.
Inspection and Service
Check bearing area (big end) for excessive wear,
score marks, running and side clearances (refer to
Specifi cations). Replace rod and cap if scored or
excessively worn.
Service replacement connecting rods are available in
STD crankpin size and 0.25 mm (0.010 in.) undersize.
0.25 mm (0.010 in.) undersized rod can be identifi ed by
drilled hole located in lower end of rod shank. Always
refer to appropriate parts information to ensure correct
replacements are used.
Remove Crankshaft
Carefully pull crankshaft from crankcase.
Inspection and Service
Crankshaft Components and Details
A
B
C
D
A Self-Tapping Screw B Flat Washer
C Plug D Crankshaft
E
G
F
H
E
Fillet Must Blend Smoothly with Bearing Journal
Surface
F High Point from Fillet Intersections
G 45° Minimum
H This Fillet Area Must Be Completely Smooth
NOTE: If crankpin is reground, visually check to ensure
fi llet blends smoothly with crankpin surface.
NOTE: To prevent repeat failures, camshaft and
crankshaft should always be replaced as a set.
Inspect gear teeth of crankshaft. If teeth are badly worn,
chipped, or some are missing, replacement of crankshaft
will be necessary.
Inspect crankshaft bearing surfaces for scoring,
grooving, etc. Some engines have bearing inserts in
crankshaft bore of oil pan and/or crankcase. Do not
replace bearings unless they show signs of damage or
are out of running clearance specifi cations. If crankshaft
turns easily and noiselessly, and there is no evidence
of scoring, grooving, etc., on races or bearing surfaces,
bearings can be reused.
Inspect crankshaft keyways. If they are worn or chipped,
replacement of crankshaft will be necessary.
Inspect crankpin for score marks or metallic pickup.
Slight score marks can be cleaned with crocus cloth
soaked in oil. If wear limits, as stated in Specifi cations
and Tolerances are exceeded, it will be necessary to
either replace crankshaft or regrind crankpin to 0.25 mm
(0.010 in.) undersize. If reground, a 0.25 mm (0.010 in.)
undersize connecting rod (big end) must then be used to
achieve proper running clearance. Measure crankpin for
size, taper, and out-of-round.
Connecting rod journal can be ground one size under.
When grinding a crankshaft, grinding stone deposits
can get caught in oil passages, which could cause
severe engine damage. Removing crankpin plug when
crankshaft is ground provides easy access for removing
any grinding deposits collected in oil passages.
Use these following procedures to remove and replace
plug.
Procedure to Remove Crankshaft Plug:
1. Drill a 3/16 in. hole through plug in crankshaft.
2. Thread a 3/4 in. or 1 in. long self-tapping screw with
a fl at washer into drilled hole. Flat washer must be
large enough to seat against shoulder of plug bore.
3. Tighten self-tapping screw until it draws plug out of
crankshaft.
Procedure to Install New Plug:
Use a single cylinder camshaft pin, as a driver and tap
plug into plug bore until it seats at bottom of bore. Make
sure plug is tapped in evenly to prevent leakage.
Remove Flywheel End Oil Seal
Remove oil seal from crankcase.
Disassembly/Inspection and Service
78 24 690 31 Rev. HKohlerEngines.com
Crankcase
Inspection and Service
Check all gasket surfaces to make sure they are free of
gasket fragments. Gasket surfaces must also be free of
deep scratches or nicks.
Inspect main bearing (if so equipped) for wear or
damage (refer to Specifi cations). Replace crankcase
using a miniblock or short block as required.
Check cylinder bore wall for scoring. In severe cases,
unburned fuel can cause scuffi ng and scoring of cylinder
wall. It washes necessary lubricating oils off piston and
cylinder wall. As raw fuel seeps down cylinder wall,
piston rings make metal to metal contact with wall.
Scoring of cylinder wall can also be caused by localized
hot spots resulting from blocked cooling fi ns or from
inadequate or contaminated lubrication.
If cylinder bore is badly scored, excessively worn,
tapered, or out-of-round, resizing is necessary. Use an
inside micrometer to determine amount of wear (refer
to Specifi cations), then select nearest suitable oversize
of either 0.25 mm (0.010 in.) or 0.50 mm (0.020 in.).
Resizing to one of these oversizes will allow usage of
available oversize piston and ring assemblies. First,
resize using a boring bar, then use these following
procedures for honing cylinder.
Honing
Detail
A
A 23°-33° Crosshatch
NOTE: Kohler pistons are custom-machined to exacting
tolerances. When oversizing a cylinder, it should
be machined exactly 0.25 mm (0.010 in.) or 0.50
mm (0.020 in.) over new diameter
(Specifi cations). Corresponding oversize Kohler
replacement piston will then fi t correctly.
While most commercially available cylinder hones can
be used with either portable drills or drill presses, use
of a low speed drill press is preferred as it facilitates
more accurate alignment of bore in relation to crankshaft
crossbore. Honing is best accomplished at a drill speed
of about 250 RPM and 60 strokes per minute. After
installing coarse stones in hone, proceed as follows:
1. Lower hone into bore and after centering, adjust so
stones are in contact with cylinder wall. Use of a
commercial cutting-cooling agent is recommended.
2. With lower edge of each stone positioned even with
lowest edge of bore, start drill and honing process.
Move hone up and down while resizing to prevent
formation of cutting ridges. Check size frequently.
3. When bore is within 0.064 mm (0.0025 in.) of
desired size, remove coarse stones and replace
them with burnishing stones. Continue with
burnishing stones until bore is within 0.013 mm
(0.0005 in.) of desired size and then use fi nish
stones (220-280 grit) and polish bore to its fi nal size.
A crosshatch should be observed if honing is done
correctly. Crosshatch should intersect at
approximately 23°-33° off horizontal. Too fl at an
angle could cause rings to skip and wear
excessively, and too steep an angle will result in high
oil consumption.
4. After resizing, check bore for roundness, taper, and
size. Use an inside micrometer, telescoping gauge,
or bore gauge to take measurements. These
measurements should be taken at 3 locations in
cylinder – at top, middle, and bottom. Two
measurements should be taken (perpendicular to
each other) at each location.
Clean Cylinder Bore After Honing
Proper cleaning of cylinder walls following boring and/
or honing is very critical to a successful overhaul.
Machining grit left in cylinder bore can destroy an engine
in less than 1 hour of operation after a rebuild.
Final cleaning operation should always be a thorough
scrubbing with a brush and hot, soapy water. Use a
strong detergent capable of breaking down machining
oil while maintaining a good level of suds. If suds break
down during cleaning, discard dirty water and start again
with more hot water and detergent. Following scrubbing,
rinse cylinder with very hot, clear water, dry it completely,
and apply a light coating of engine oil to prevent rusting.
Disassembly/Inspection and Service
7924 690 31 Rev. H KohlerEngines.com
Measuring Piston-to-Bore Clearance
Piston Detail
A
A 6 mm (0.24 in.)
NOTE: Do not use a feeler gauge to measure piston-to-
bore clearance – it will yield inaccurate
measurements. Always use a micrometer.
Before installing piston into cylinder bore, it is
necessary clearance be accurately checked. This step
is often overlooked, and if clearances are not within
specifi cations, engine failure will usually result.
Use these following procedures to accurately measure
piston-to-bore clearance:
1. Use a micrometer and measure diameter of piston 6
mm (0.24 in.) above bottom of piston skirt and
perpendicular to piston pin.
2. Use an inside micrometer, telescoping gauge, or
bore gauge and measure cylinder bore. Take
measurement approximately 63.5 mm (2.5 in.) below
top of bore and perpendicular to piston pin.
3. Piston-to-bore clearance is diff erence between bore
diameter and piston diameter (step 2 minus step 1).
Disassembly/Inspection and Service
80 24 690 31 Rev. HKohlerEngines.com
81
Reassembly
24 690 31 Rev. H KohlerEngines.com
NOTE: Make sure engine is assembled using all
specifi ed torque values, tightening sequences,
and clearances. Failure to observe specifi cations
could cause severe engine wear or damage.
Always use new gaskets. Apply a small amount
of oil to threads of critical fasteners before
assembly, unless a Sealant or Loctite
®
is
specifi ed or preapplied.
Make sure all traces of any cleaner are removed before
engine is assembled and placed into operation. Even
small amounts of these cleaners can quickly break down
lubricating properties of engine oil.
Check oil pan, crankcase, and cylinder heads to be
certain that all old sealing material has been removed.
Use gasket remover, lacquer thinner, or paint remover
to remove any remaining traces. Clean surfaces with
isopropyl alcohol, acetone, lacquer thinner, or electrical
contact cleaner.
Install Flywheel End Oil Seal
Oil Seal Detail
B
A
A 4.5 mm (0.177 in.) B Oil Seal
1. Make sure that seal bore of crankcase is clean and
free of any nicks or burrs.
2. Apply a light coat of engine oil to outside diameter of
oil seal.
3. Drive oil seal into crankcase using a seal driver.
Make sure oil seal is installed straight and true in
bore to depth shown.
Install Crankshaft
1. Lubricate crankshaft journals and connecting rod
bearing surfaces with engine oil.
2. Carefully slide fl ywheel end of crankshaft through
main bearing in crankcase.
Crankcase Components
C
D
E
B
F
G
P
I
J
K
L
M
N
O
Q
R
A
H
Y
S
T
U
W
V
X
A Oil Pan Seal B Oil Pan (Style A)
C
Gerotor Gears
(Style A)
D
Oil Pump Assembly
(Style A)
E Governor Shaft F Governor Washer
G Governor Gear H Governor Cup
I Crankshaft J Connecting Rod
K Piston L Piston Pin
M
Piston Pin Retainer
Clip
N Piston Rings
O Camshaft P Oil Pan Gasket
Q
Governor Cross
Shaft
R Crankcase
S
Oil Pump Assembly
(Style B)
T
Outer Gerotor Gear
(Style B)
U
Oil Pump Cover
O-ring (Style B)
V Spring (Style B)
W Ball (Style B) X
Oil Screen
(Style B)
Y Oil Pan (Style B)
82
Reassembly
24 690 31 Rev. HKohlerEngines.com
Install Connecting Rods with Pistons and Rings
Piston Detail
A
B
A Cylinder 1 B Cylinder 2
NOTE: Cylinders are numbered on crankcase. Make
sure to install piston, connecting rod, and end
cap into its appropriate cylinder bore as
previously marked at disassembly. Do not mix
end caps and connecting rods.
NOTE: Proper orientation of piston/connecting rod
assemblies inside engine is extremely important.
Improper orientation can cause extensive wear
or damage. Be certain pistons and connecting
rods are assembled exactly as shown.
NOTE: Align chamfer of connecting rod with chamfer of
its mating end cap. When installed, fl at faces of
connecting rods should face each other. Faces
with raised rib should be toward outside.
1. If piston rings were removed, see Disassembly/
Inspection and Service procedure to install new
rings.
2. Lubricate cylinder bore, piston, and piston rings with
engine oil. Compress rings using a piston ring
compressor.
3. Make sure FLY stamping on piston is facing towards
fl ywheel side of engine. Use a hammer with a rubber
grip and gently tap piston into cylinder as shown. Be
careful that oil ring rails do not spring free between
bottom of ring compressor and top of cylinder.
4. Install inner rod cap to connecting rod using screws.
Two diff erent types of connecting rod screws have
been used. If 6 mm straight shank, torque in
increments to 11.6 N·m (103 in. lb.). If 6 mm straight
shank gray metallic color, it is not necessary to
lubricate this screw, torque in increments to 13.6
N·m (120 in. lb.). Illustrated instructions are provided
in service rod package.
5. Repeat above procedure for other connecting rod
and piston assembly.
Install Governor Cross Shaft
1. Lubricate governor cross shaft bearing surfaces in
crankcase with engine oil.
2. Slide small lower washer onto governor cross shaft
and install cross shaft from inside of crankcase.
3. Install nylon washer onto governor cross shaft, then
start push-on retaining ring. Hold cross shaft up in
position, place a 0.50 mm (0.020 in.) feeler gauge on
top of nylon washer, and push retaining ring down
shaft to secure. Remove feeler gauge, which will
have established proper end play.
Install Camshaft
1. Liberally apply camshaft lubricant to each of cam
lobes. Lubricate camshaft bearing surfaces of
crankcase and camshaft with engine oil.
2. Position timing mark of crankshaft gear at 12 o’clock
position.
3. Turn governor cross shaft clockwise until lower end
of shaft contacts cylinder. Make sure cross shaft
remains in this position while installing camshaft.
4. Slide camshaft into bearing surface of crankcase,
positioning timing mark of camshaft gear at 6 o’clock
position. Make sure camshaft gear and crankshaft
gear mesh with both timing marks aligned.
Oil Pump Assembly
Oil pump is mounted inside oil pan. If service was
required, and oil pump was removed, refer to assembly
procedures under Oil Pump Assembly in Disassembly/
Inspection and Service.
Governor Gear Assembly
Governor gear assembly is located inside oil pan. If
service was required, and governor was removed, refer
to assembly procedures under Disassembly/Inspection
and Service.
Install Oil Pan Oil Seal
Oil Seal Details
B
A
A Oil Seal B 6.5 mm (0.255 in.)
1. Check to make sure that there are no nicks or burrs
in crankshaft bore of oil pan.
2. Apply a light coat of engine oil to outside diameter of
oil seal.
3. Drive oil seal into oil pan using a seal driver. Make
sure oil seal is installed straight and true in bore, to
depth shown.
83
Reassembly
24 690 31 Rev. H KohlerEngines.com
Install Oil Pan Assembly
Oil Pan Fastener Torque Sequence
1
10
8
6
4
9
7
5
3
2
1. Be sure sealing surfaces have been cleaned and
prepared as described at beginning of Disassembly/
Inspection and Service. Install a new O-ring in oil
pan.
2. Check to make sure that there are no nicks or burrs
on sealing surfaces of oil pan or crankcase.
3. Use a new gasket. Before installing gasket, check to
make sure O-ring is present in counter bore around
dowel pin.
4. Make sure end of governor cross shaft is lying
against bottom of cylinder #1 inside crankcase.
5. Install oil pan to crankcase. Carefully seat camshaft
and crankshaft into their mating bearings. Rotate
crankshaft slightly to help engage oil pump and
governor gear meshes.
6. Install screws securing oil pan to crankcase. Torque
fasteners in sequence shown to 25.6 N·m (227 in.
lb.). One mounting screw has a thread sealant
patch. This screw is typically installed in number 10
hole shown. Reapply pipe sealant with Tefl on
®
(Loctite
®
592™ PST
®
Thread Sealant or equivalent)
to number 10 oil pan screw as required.
Install Stator and Backing Plate
1. Apply pipe sealant with Tefl on
®
(Loctite
®
592
™
PST
®
Thread Sealant or equivalent) to stator mounting
holes.
2. Position stator aligning mounting holes so that leads
are at bottom, towards crankcase.
3. Install and torque screws to 6.2 N·m (55 in. lb.) for
new holes or 4.0 N·m (35 in. lb.) for used holes.
4. Route stator leads in crankcase channel, then install
backing plate. Secure with screws. Torque screws
10.7 N·m (95 in. lb.) for new holes or 7.3 N·m (65 in.
lb.) for used holes.
Install Flywheel
CAUTION
Damaging Crankshaft and Flywheel Can
cause personal injury.
Using improper procedures can lead to broken
fragments. Broken fragments could be thrown from
engine. Always observe and use precautions and
procedures when installing fl ywheel.
Flywheel Components
A
B
D
C
A Flywheel Fan B Flywheel
C Stator D Backing Plate
84
Reassembly
24 690 31 Rev. HKohlerEngines.com
2. Install fl ywheel onto crankshaft being careful not to
shift woodruff key.
3. Install screw and washer.
4. Use a fl ywheel strap wrench or holding tool to hold
fl ywheel. Torque screw securing fl ywheel to
crankshaft to 71.6 N·m (52.8 ft. lb.).
Install Fan
NOTE: Position locating tabs on back of fan into locating
holes of fl ywheel.
1. Install fan onto fl ywheel. Fan will be fastened to
fl ywheel when metal debris screen is installed.
NOTE: Before installing fl ywheel, make sure crankshaft
taper and fl ywheel hub are clean, dry, and
completely free of any lubricants. Presence of
lubricants can cause fl ywheel to be over
stressed and damaged when screw is torqued to
specifi cations.
NOTE: Make sure fl ywheel key is installed properly in
keyway. Flywheel can become cracked or
damaged if key is not properly installed.
1. Install woodruff key into keyway of crankshaft. Make
sure that key is properly seated and parallel with
shaft taper.
Cylinder Head Components
A
B
C
D
E
F
H
I
J
K
G
N
P
O
Q
L
M
R
A Valve Cover B Valve Cover Gasket C Hex Flange Screw D Rocker Arm Pivot
E Rocker Arm F Push Rod G Hydraulic Lifter H Valve Cap
I Valve Keeper J Valve Spring K Valve Seal L
Valve Spring
Retainer
M Spark Plug N Cylinder Head O
Cylinder Head
Gasket
P Valve
Q Dowel Pin R
Heat Sensor Switch
(PCV680LE,
PCV740LE)
85
Reassembly
24 690 31 Rev. H KohlerEngines.com
Install Hydraulic Lifters
NOTE: Hydraulic lifters should always be installed in
same position as before disassembly. Exhaust
lifters are located on output shaft (oil pan) side
of engine while intake lifters are located on fan
side of engine. Cylinder numbers are embossed
on top of crankcase and each cylinder head.
1. See Servicing Hydraulic Lifters in Disassembly/
Inspection and Service.
2. Apply camshaft lubricant to bottom surface of each
lifter. Lubricate hydraulic lifters and lifter bores in
crankcase with engine oil.
3. Note mark or tag identifying hydraulic lifters as either
intake or exhaust and cylinder 1 or 2. Install
hydraulic lifters into their appropriate locations in
crankcase. Do not use a magnet.
4. If breather reeds and stops were removed from
crankcase, reinstall them at this time and secure
with screw. Torque screw to 4.0 N·m (35 in. lb.).
Valve Stem Seals
These engines use valve stem seals on intake valves
and on exhaust valves. Use a new seal whenever valve
is removed or if seal is deteriorated or damaged in any
way. Never reuse an old seal.
Assemble Cylinder Heads
Prior to installation, lubricate all components with engine
oil, paying particular attention to lip of valve stem seal,
valve stems, and valve guides. Install following items in
order listed below using a valve spring compressor.
• Intake and exhaust valves.
• Valve spring retainers.
• Valve springs.
• Valve spring caps.
• Valve spring keepers.
Install Cylinder Heads
Torque Sequence
#1 #2
NOTE: Match numbers embossed on cylinder heads
and crankcase.
NOTE: PCV680LE and PCV740LE engines have a heat
sensor switch secured on #2 cylinder head.
Reinstall switch as noted in disassembly.
1. Check to make sure there are no nicks or burrs on
sealing surfaces of cylinder head or crankcase.
2. If all of studs were left intact, go to Step 6. If any
studs were disturbed or removed, install new studs
as described in Step 3. Do not use/reinstall any
loosened or removed studs.
3. Install new mounting stud(s) into crankcase.
a. Thread and lock mounting nuts together on
smaller diameter threads.
b. Thread opposite end of stud, with preapplied
locking compound, into crankcase, until specifi ed
height from crankcase surface is achieved. When
threading in studs, use a steady tightening motion
without interruption until proper height is
obtained. Otherwise frictional heat from engaging
threads may cause locking compound to set up
prematurely.
Studs closest to lifters must have an exposed height of
75 mm (2 15/16 in.).
Studs furthest from lifters must have an exposed height
of 69 mm (2 3/4 in.).
c. Remove nuts and repeat procedure as required.
4. Check that dowel pins are in place and install a new
cylinder head gasket (part number facing up).
5. Install cylinder head. Match numbers on cylinder
heads and crankcase. Make sure head is fl at on
gasket and dowel pins.
6. Lightly lubricate exposed (upper) threads of studs
with engine oil. Install a fl at washer and nut onto
each of mounting studs. Torque nuts in 2 stages; fi rst
to 16.9 N·m (150 in. lb.), then fi nally to 33.9 N·m
(300 in. lb.), following sequence.
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Install Push Rods and Rocker Arms
NOTE: Push rods should always be installed in same
position as before disassembly.
NOTE: Two diff erent screws have been used to secure
rocker arms/pivots. Black screws are used with
heads that have a rocker pivot hole depth of
approximately 21 mm (0.83 in.). Silver screws
are used with heads that have a rocker pivot
hole depth of approximately 35 mm (1.38 in.).
1. Note mark or tag identifying push rod as either
intake or exhaust and cylinder 1 or 2. Dip ends of
push rods in engine oil and install, making sure that
each push rod ball seats in its hydraulic lifter socket.
2. Apply grease to contact surfaces of rocker arms and
rocker arm pivots. Install rocker arms and rocker arm
pivots on one cylinder head, and start screws.
3. Torque black screws to 18.1 N·m (160 in. lb.).
Torque silver screws to 13.6 N·m (120 in. lb.).
4. Use a spanner wrench or rocker arm lifting tool to lift
rocker arms and position push rods underneath.
5. Repeat above steps for remaining cylinder. Do not
interchange parts from cylinder heads.
6. Rotate crankshaft to check for free operation of
valve train. Check clearance between valve spring
coils at full lift. Minimum allowable clearance is 0.25
mm (0.010 in.).
Check Assembly
Important: Rotate crankshaft a minimum of 2 revolutions
to check longblock assembly and overall proper
operation.
Install Spark Plugs
1. Check gap using wire feeler gauge. Adjust gap to
0.76 mm (0.030 in.).
2. Install plug into cylinder head.
3. Torque plug to 27 N·m (20 ft. lb.).
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External Engine Components
AA
A
B
C
I
Z
U
O
M
V
J
K
L
F
G
W
N
O
H
T
X
R
S
Q
N
Y
P
D
E
A Debris Screen Guard B Debris Screen C Air Cleaner Bracket D
High Pressure Fuel
Line Assembly
E Fuel Quick Connect F
Gaseous Propane
Fuel Injector
G
MAP or TMAP
Sensor
H
Crankshaft Position
Sensor (Earlier
Design Bracket)
I Oil Cooler O-Ring J Oil Cooler K Nipple L Oil Filter
M Ignition Coil N Barrel Baffl e O Valley Baffl e P Breather Cover
Q
Breather Cover
Gasket
R Oil Sentry
™
S
Oil Temperature
Sensor
T
Throttle Body
Assembly
U
Air Temperature
Sensor
V Dipstick Tube W Oil Fill Cap/Dipstick X Air Cleaner
Y Breather Hose Z Breather Separator AA
Crankshaft Position
Sensor (Later Design
Bracket)
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Install Intake Manifold
Torque Sequence
1
2
3
4
1. Install intake manifold (with high pressure fuel line
assembly) and new gaskets, with wiring harness
attached, to cylinder heads. Slide any wiring harness
clips onto appropriate bolts before installing. Make
sure gaskets are in proper orientation. Using
sequence shown, torque screws in 2 stages, fi rst to
7.8 N·m (69 in. lb.), then to 10.5 N·m (93 in. lb.).
2. Install ground terminal to crankcase post with a
silver screw. Torque to 4.0 N·m (35 in. lb.) into used
holes or 6.2 N·m (55 in. lb.) in new holes.
3. Install wire harness clip to other crankcase post.
Torque to 4.0 N·m (35 in. lb.) into used holes or 6.2
N·m (55 in. lb.) in new holes.
4. Place wire harness conduit in clip and snap clip
together.
Install Fuel Injectors
NOTE: Ensure all parts are clean, undamaged and free
of debris and make sure electrical connectors
have seal in place.
O-rings and retaining clips should be replaced
any time fuel injector is separated from its
normal mounting position.
1. Lightly lubricate fuel injector O-rings with clean
engine oil.
2. Push retaining clip onto fuel injector, aligning clip.
3. Press fuel injector into fuel injector cap until retaining
clip snaps into place.
4. Press fuel injector into bore in intake manifold and
rotate to original position.
5. Install fuel injector cap screw into intake manifold
and torque to 7.3 N·m (65. in. lb.).
6. Push electrical connector on fuel injector making
sure a good connection is made.
7. Repeat steps 1 through 6 for other fuel injector.
Install Manifold Absolute Pressure (MAP) Sensor or
Temperature/Manifold Absolute Pressure (TMAP)
Sensor
NOTE: Ensure all parts are clean, undamaged and free
of debris and make sure electrical connector has
seal in place.
1. Lightly oil MAP or TMAP sensor O-ring and push
sensor into bore in intake manifold.
2. Torque screw to 7.3 N·m (65 in. lb.).
3. Push electrical connector on MAP or TMAP sensor
making sure a good connection is made.
Install Crankshaft Position Sensor
NOTE: Ensure all parts are clean, undamaged and free
of debris and make sure electrical connectors
have seal in place.
NOTE: On engines with earlier design bracket, an air
gap must be set when installing. Later design
brackets require no adjustment.
1. Install crankshaft position sensor and bracket
assembly to crankcase posts.
2. On engines with earlier design bracket, snug screws
and check air gap of sensor with a feeler gauge. It
must be 0.20-0.70 mm (0.008-0.027 in.). Torque
bracket screws to crankcase to 4.0 N·m (35 in. lb.)
into used holes or 6.2 N·m (55 in. lb.) into new holes.
On engines with later design bracket, secure bracket
assembly to crankcase posts. Torque bracket screws
to crankcase to 4.0 N·m (35 in. lb.) into used holes
or 6.2 N·m (55 in. lb.) into new holes.
3. Push electrical connector on crankshaft position
sensor making sure a good connection is made.
Install Valve Covers
Torque Sequence
1
2
3
4
NOTE: PCV680LE and PCV740LE engines have a
main support bracket secured with inner valve
cover screws. Reinstall support bracket as noted
in disassembly.
1. Make sure sealing surfaces are clean.
2. Make sure there are no nicks or burrs on sealing
surfaces.
3. Install a new O-ring in groove of each cover.
4. Position covers on cylinder heads. Locate cover with
oil separator hole on cylinder 1. Install screws in
each cover and fi nger tighten.
5. Torque valve cover fasteners to 9.0 N·m (80 in. lb.).
Connect Heat Sensor Switch PCV680LE, PCV740LE
Connect lead to heat sensor switch terminal.
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Install Breather Cover and Inner Baffl es
Torque Sequence
1&5
2
3
4
1. Be sure sealing surfaces of crankcase and breather
cover are clean of old gasket material. Do not scrape
surfaces as this could result in leakage. Use a new
gasket when installing breather cover.
2. Check to make sure there are no nicks or burrs on
sealing surfaces.
3. Position breather gasket and cover on crankcase.
Install screws in locations 3 and 4. Finger tighten at
this time.
4. Install inner baffl es using remaining screws and
fi nger tighten. Do not torque screws at this time; they
will be tightened after blower housing.
Install Oil Temperature Sensor
NOTE: Ensure part is clean, undamaged and free of
debris and make sure electrical connector has
seal in place.
1. Lightly lubricate oil temperature sensor O-ring and
install oil temperature sensor into breather cover.
2. Torque sensor to 7.3 N·m (65 in. lb.).
3. Push electrical connector on oil temperature sensor
making sure a good connection is made.
Install Oil Sentry
™
(If equipped)
1. Apply pipe sealant with Tefl on
®
(Loctite
®
592™ PST
®
Thread Sealant or equivalent) to threads of Oil
Sentry
™
switch and install it into breather cover.
Torque to 4.5 N·m (40 in. lb.).
2. Connect wire lead (green) to Oil Sentry™ terminal.
Install Blower Housing and Outer Baffl es
NOTE: Do not completely tighten screws until all items
are installed to allow shifting for hole alignment.
1. Slide blower housing into position over front edge of
inner baffl es. Start a few screws to hold it in place.
2. Position outer baffl es and secure using M6 screws
Install M6 screws (20 mm long) into intake port side
of cylinder heads, including any lifting strap. Install
M6 screws (16 mm long) into exhaust port side of
cylinder head. Install short M5 screws (10 mm long)
in upper mounting holes of outer baffl es (into
backing plate). Be sure any leads are routed out
through proper off sets or notches, so they will not be
pinched between blower housing and baffl es.
3. Insert and tighten all remaining blower housing and
baffl e screws with exception of rectifi er-regulator
grounding bracket screw. Torque all blower housing
and baffl e M6 screws assembled into aluminum to
10.7 N·m (95 in. lb.) for a new hole, or 7.3 N·m (65
in. lb.) for a used hole. Torque all blower housing
and baffl e M5 screws assembled into sheet metal
(backing plate)to 2.8 N·m (25 in. lb.) for new holes,
or 2.3 N·m (20 in. lb.) for used holes.
4. Torque breather cover screws to 11.3 N·m (100 in.
lb.) into new holes or 7.3 N·m (65 in. lb.) into used
holes in sequence shown. Note fi rst screw is torqued
a second time.
Install Reconnect Rectifi er-Regulator
B
A
C
A Ground Strap
B Ground Lead
C Ground Lug
NOTE: Rectifi er-regulator middle terminal (B+) is off set
(not equally spaced) from outer terminals (AC).
Verify rectifi er-regulator plug is assembled to
match terminal off set of rectifi er-regulator.
1. Install rectifi er-regulator in blower housing if
removed previously. Reinstall any washers and hose
clamps.
a. If engine has ground strap, secure it against outer
side of rectifi er-regulator with a silver or green
plated screw.
b. If engine has ground lead that secures in same
hole as rectifi er-regulator fastener, secure one
end to rectifi er-regulator and other end to backing
plate.
c. If engine has ground lead that secures in
separate ground lug fastener hole in rectifi er-
regulator, secure one end to ground lug and other
end to backing plate.
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2. Torque black rectifi er-regulator screws to 1.4 N·m
(12.6 in. lb.).
a. Torque silver or green ground strap screw to
2.8 N·m (25 in. lb.) into new holes or 2.3 N·m
(20 in. lb.) into used holes.
b. Ground lead that secures in same hole as
rectifi er-regulator fastener, torque screw securing
to backing plate to 2.8 N·m (25 in. lb.) into new
holes or 2.3 N·m (20 in. lb.) into used holes.
c. Ground lead that secures in ground lug hole of
rectifi er-regulator and to backing plate, torque
screws to 5.6 N·m (50 in. lb.) into new holes or
4.0 N·m (35 in. lb.) into used holes.
3. Connect plug to rectifi er-regulator. If purple wire was
removed, verify locking tang is raised on terminal
and push wire terminal into plug prior to connecting
to rectifi er-regulator.
Install Metal Debris Screen
Spring Washer Details
A
A Spring Washer
A
B
C
D
E
A Metal Debris Screen B Fan
C Flywheel D Spacer
E Hex Bolt
1. Verify locating tabs on back of fan are inserted into
locating holes on fl ywheel.
2. To assist assembly, fi nd intake manifold studs with
M6 thread at least 100 mm in length to be used as
guide pins. Insert intake manifold studs through
cooling fan mounting holes and thread them 4 or 5
turns into fl ywheel.
3. Install a spring washer on each stud with concave
side down toward cooling fan.
4. Install a spacer on each stud with stepped end
down. Smaller diameter should extend through
spring washer and fan, so tip is resting on fl ywheel,
and shoulder is resting on spring washer.
5. Install support ring on studs, so it is resting on
spacers. Then install metal screen on top of support
ring.
6. Install a plain washers on each of screws. Apply
Loctite
®
242
®
to screw threads.
7. Carefully remove studs and replace with screws.
Torque screws to 9.9 N·m (88 in. lb.). Repeat
procedure for other studs and screws.
Install Oil Separator and Hardware
1. Ensure rubber oil separator grommet is in good
condition. Insert rubber grommet into valve cover.
Push oil separator into rubber grommet in valve
cover.
2. Secure oil separator to blower housing, placing
spacer and oil separator bracket against blower
housing and securing with strap and screws. Torque
screws to 2.3 N·m (20 in. lb.).
Install Electric Starter Motor and ECU Bracket
1. Install electric starter motor using screws. Position
ECU bracket.
2. Torque screws to 16.0 N·m (142 in. lb.).
3. Connect leads to solenoid.
4. Install dipstick tube and align mounting hole with
threaded hole in ECU bracket. Secure with M5
screw. Torque screw to 6.2 N·m (55 in. lb.) into new
hole or 4.0 N·m (35 in. lb.) into used hole.
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ECU
Install Electronic Control Unit (ECU)
B
A
C
A
Electronic Control
Unit (ECU)
B ECU Bracket
C Starter
NOTE: ECU pins should be coated with a thin layer of
electrical grease to prevent fretting and
corrosion and may need to be reapplied if ECU
is being reused.
1. Install ECU to ECU bracket using screws. Torque M5
screws to 6.2 N·m (55 in. lb.) into new holes or 4.0
N·m (35 in. lb.) into used holes.
2. Connect Black and Grey electrical connectors.
Connectors and ECU are keyed in such a way so
they cannot be installed incorrectly.
Install Throttle Body
NOTE: Ensure all parts are clean, undamaged and free
of debris and make sure electrical connector has
seal in place.
NOTE: Earlier engines have separate IAT and MAP
sensors.
1. Install a new throttle body O-ring prior to installation.
Make sure all holes align and are open.
2. Install throttle body, throttle position sensor, intake
air temperature (IAT) sensor (earlier engines only),
throttle linkage, spring and bushing, as an assembly.
3. Install air cleaner bracket to throttle body with
screws. Torque screws to 9.9 N·m (88 in. lb.).
4. Connect breather separator hose to top of throttle
body using a pliers to compress spring clip. Route
hose through housing by pressing hose into cutout
of blower housing. Position abrasion sleeve.
5. On earlier engines with separate intake air
temperature (IAT) and MAP sensor, push electrical
connector onto IAT sensor making sure a good
connection is made by listening for a click.
6. Connect 5/32 in. I.D. vent hose to bottom of throttle
body. (Other end of vent hose connects to vaporizer/
regulator.)
7. Push electrical connector onto throttle position
sensor making sure a good connection is made.
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Install Vaporizer/Regulator/Lock-Off
WARNING
Propane is extremely fl ammable and is heavier than air and
tends to settle in low areas where a spark or fl ame could
ignite gas. Do not start or operate this engine in a poorly
ventilated area where leaking gas could accumulate and
endanger safety of persons in area.
To ensure personal safety, installation and repair of propane
fuel supply systems must be performed only by qualifi ed
propane system technicians. Improperly installed and
maintained propane equipment could cause fuel supply
system or other components to malfunction, causing gas
leaks.
Observe federal, state and local laws governing propane
fuel, storage, and systems.
Explosive Fuel can cause fi res and severe
burns.
If a gaseous odor is detected, ventilate area
and contact an authorized service technician.
Vaporizer/Regulator/Lock-Off Assembly
A
H
B
C
F
G
D
E
I
H
H
A Vacuum Line B Vaporizer/Regulator C Inlet Fitting D Lock-Off Assembly
E Propane Fuel Filter F Bracket G Outlet Fitting H Oetiker Clamp
I Straight Fitting
1. Connect fuel line quick connect (on high pressure fuel line assembly) to straight fi tting (in fuel line after propane
fuel fi lter).
2. Apply pipe sealant with Tefl on
®
(Loctite
®
592
™
PST
®
Thread Sealant or equivalent) to regulator bracket screws,
after fi rst 3-4 lead-in threads. Install screws and secure regulator bracket to crankcase. Torque screws to 11.9
N·m (105 in. lb.). With nut installed on center back of vaporizer/regulator, position regulator so nut comes through
key hole slot in bracket, installing vaporizer/regulator (keeping fuel lines, propane fuel fi lter assembled) to bracket.
Torque nut to 19.8 N·m (175 in. lb.).
3. Connect vacuum line to barb on front of vaporizer/regulator.
4. Reconnect electrical plug to lock-off assembly.
5. If any Oetiker clamps were cut during disassembly, slide a new Oetiker clamp onto fuel line and connect fuel line.
Only use an Oetiker clamp pliers to crimp Oetiker clamps. Oetiker clamp crimp must point up, away from top of
vaporizer/regulator or propane fuel fi lter and abrasion sleeve must be positioned over Oetiker clamp.
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24 690 31 Rev. H KohlerEngines.com
Install External Governor Controls
A
N
C
E
G
F
D
J
I
L
H
K
M
B
A
Throttle Control Shaft
Nut
B Throttle Control Shaft C Throttle Control Lever D Washer
E Spring F Control Bracket G
Throttle Control
Bracket (lower)
H Governor Spring
I Governor Lever J
Throttle Linkage
Spring
K Bushing L Throttle Linkage
M Nut N Governor Cross Shaft
1. Install governor lever onto governor cross shaft.
2. Make sure throttle linkage, linkage spring, black linkage bushing are connected to governor lever and to throttle
lever on throttle body.
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Assemble Top Mount Control Panel
1. Install lower support control bracket with throttle
control shaft.
2. Install top mount control panel over throttle control
shaft. Secure control panel to blower housing with
screws.
3. Assemble throttle control lever and applicable
hardware to throttle control shaft.
4. Attach governor spring to previously marked hole on
governor lever.
Install Heat Defl ectors PCV680LE, PCV740LE
B B
A
A
C
C
A Heat Defl ector B Nut
C Screw
Position a heat defl ector on each cylinder head and
secure with screw and nut.
Install Air Cleaner Assembly
Refer to Air Cleaner/Intake for air cleaner reassembly
procedure.
Heavy-Duty Air Cleaner
1. Install air cleaner assembly onto throttle body
mounting studs. Secure and torque nuts to 7.4-9.0
N·m (65.5-80 in. lb.).
2. Install and tighten two upper mounting screws
securing air cleaner to mounting bracket. Torque
screws to 9.9 N·m (88 in. lb.).
Low-Profi le Air Cleaner
1. Verify O-ring is present around machined O.D. of
throttle body and place air cleaner base onto throttle
body studs. Secure air cleaner base using three
nuts. Attach air cleaner base bracket to cylinder
heads with screws behind any control panel or
bracket. Attach air cleaner base to lower bracket with
M5 screws through lower section of base. Torque
nuts to 7.4-9.0 N·m (65.5-80 in. lb.), and lower M5
mounting screws to 2.3 N·m (20 in. lb.).
2. Install air cleaner components as described in Air
Cleaner/Intake.
Setting Initial Governor Adjustment
1. Move governor lever toward throttle body as far as it
will go (wide-open throttle) and hold in position.
2. Insert a nail into hole on cross shaft and rotate shaft
counterclockwise as far as it will turn, then torque
nut to 7.1 N·m (63 in. lb.).
Oxygen Sensor Wire Detail
A
A
Keep a minimum of 25 mm (1.0 in.) radius at
grommet.
NOTE: Always route harness away from hot exhaust
and away from moving parts.
Install Muffl er (if equipped) PCV680, PCV740
1. Install port liners (if equipped), slotted end fi rst, into
exhaust ports until fi nger tight. (Exhaust components
will press them to fi nal depth). Install exhaust
gaskets and muffl er.
2. Install remaining muffl er support hardware (screws
and nuts) and torque to 9.9 N·m (88 in. lb.).
3. Install nuts on exhaust studs. Torque nuts to 27.8
N·m (246 in. lb.).
4. Install oxygen sensor, torque to 50.1 N·m (37 ft. lb.),
and connect to wire harness.
Install Muffl er PCV680LE, PCV740LE
1. If not already installed, position main support bracket
and oxygen sensor clip/bracket on valve covers;
secure with valve cover screws. Torque screws to
9.0 N·m (80 in. lb.).
2. Install port liners, slotted end fi rst, into exhaust ports
until fi nger tight. (Exhaust components will press
them to fi nal depth).
3. Install exhaust gaskets onto exhaust studs. Position
muffl er and start screws securing muffl er to main
support bracket. Install nuts on exhaust studs.
Torque screws to 9.9 N·m (88 in. lb.). Torque nuts to
27.8 N·m (246 in. lb.).
4. Install oxygen sensor, torque to 50.1 N·m (37 ft. lb.),
and connect to wire harness.
Install Oil Cooler
1. Secure adapter to oil pan with oil fi lter nipple. Torque
oil fi lter nipple to 28.5 N·m (21 ft. lb.).
2. Verify all fuel and vent hoses are routed properly and
not pinched. Install screws to secure oil cooler to
blower housing. Torque top screw to 2.8 N·m (25 in.
lb.) and lower screw to 2.3 N·m (20 in. lb.).
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24 690 31 Rev. H KohlerEngines.com
Install Oil Filter and Fill Crankcase with Oil
NOTE: If testing oil pressure after completing
reassembly, install oil pressure adapter instead
of oil fi lter.
1. Prefi ll a new oil fi lter following instructions.
2. Place new fi lter in shallow pan with open end up. Fill
with new oil until oil reaches bottom of threads. Allow
2 minutes for oil to be absorbed by fi lter material.
3. Apply a thin fi lm of clean oil to rubber gasket on oil
fi lter.
4. Refer to instructions on oil fi lter for proper
installation.
5. Fill crankcase with new oil. Level should be at top of
indicator on dipstick.
6. Reinstall oil fi ll cap/dipstick and tighten securely.
Connect Spark Plug Leads
1. Connect leads to spark plugs.
Prepare Engine for Operation
NOTE: If ECU or TPS/throttle body were replaced, an
ECU Reset and TPS Learn is required. Refer to
ECU Reset and TPS Learn procedures in Fuel
System.
Engine is now completely reassembled. Before starting
or operating engine, be sure to follow steps below.
1. Make sure all hardware is tightened securely.
2. Make sure oil drain plugs, Oil Sentry
™
pressure
switch, and a new oil fi lter are installed.
3. Fill crankcase with correct amount, weight, and type
of oil. Refer to oil recommendations and procedures
in Maintenance, Specifi cations, and Lubrication
System.
4. Adjust idle speed adjusting screw as necessary.
Refer to Fuel System.
5. Turn on fuel supply.
Sensitivity Adjustment
B
A
C
D
E
A Governor Lever B Hole 1
C Hole 2 D Hole 3
E Hole 4
Governor sensitivity is adjusted by repositioning
governor spring in holes of governor lever. If speed
surging occurs with a change in engine load, governor
is set too sensitive. If a big drop in speed occurs when
normal load is applied, governor should be set for
greater sensitivity. Adjust as follows:
1. To increase sensitivity, move spring closer to
governor lever pivot point.
2. To decrease sensitivity, move spring away from
governor lever pivot point.
Testing Engine
It is recommended engine be operated on a stand or
bench prior to installation in piece of equipment.
1. Start engine, inspect for leaks and check to make
certain that oil pressure (20 psi or more) is present.
Run engine at idle for 2-3 minutes, then 5-6 minutes
more between idle and midrange.
2. Adjust idle speed screw located on throttle body as
necessary. Standard idle speed setting for EFI
engines is 1500 RPM, but certain applications might
require a diff erent setting.
3. Adjust high-speed stop as necessary located on
control panel (if equipped). Make sure maximum
engine speed does not exceed 4200 RPM (no load).
© 2021 by Kohler Co. All rights reserved.
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