Kohler Kohler-Service-and-Repair-Manuals/Kohler-Service-Repair-Manual-Aegis-LH630-LH685-LH750-LH760 Repair Manuals
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
SERVICE MANUAL
AEGIS
LIQUID-COOLED
HORIZONTAL CRANKSHAFT
LH630, LH685, LH750, LH760
™
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Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Contents
Section 1. Safety and General Information ............................................................................
1
Section 2. Special Tools ..........................................................................................................
Section 3. Troubleshooting .....................................................................................................
Section 4. Air Cleaner System.................................................................................................
Section 5. Fuel System and Governor....................................................................................
Section 5B. Electronic Fuel Injection (EFI) Fuel System ......................................................
Section 6. Lubrication System ................................................................................................
Section 7. Cooling System ......................................................................................................
2
3
4
5
5B
6
7
Section 8. Electrical System and Components .....................................................................
Section 9. Disassembly ...........................................................................................................
Section 10. Inspection and Reconditioning ...........................................................................
Section 11. Reassembly...........................................................................................................
8
9
10
11
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Safety and General Information
LH630, LH685, LH750, LH760
Section 1
Safety and General Information
Safety Precautions
To ensure safe operations please read the following statements and understand their meaning. Also
refer to your equipment manufacturer's manual for other important safety information. This manual
contains safety precautions which are explained below . Please read carefully.
WARNING
Warning is used to indicate the presence of a hazard that can cause severe personal injury, death,
or substantial property damage if the warning is ignored.
Section 1
1
CAUTION
Caution is used to indicate the presence of a hazard that will or can cause minorpersonal injury or
property damage if the caution is ignored.
NOTE
Note is used to notify people of installation, operation, or maintenance information that is important
but not hazard-related.
For Y our Safety!
These precautions should be followed at all times. Failure to follow these precautions could result in
injury to yourself and others.
WARNING
Accidental Starts can cause
severe injury or death.
Disconnect and ground spark plug
leads before servicing.
Accidental St arts!
Disabling engine. Accidental
starting can cause severe injury
or death. Before working on the
engine or equipment, disable the
engine as follows: 1) Disconnect the
spark plug lead(s). 2) Disconnect
negative (-) battery cable from
battery .
WARNING
Rotating Parts can cause severe
injury.
Stay away while engine is in
operation.
Rotating Part s!
Keep hands, feet, hair, and
clothing away from all moving
parts to prevent injury. Never
operate the engine with covers,
shrouds, or guards removed.
Hot Parts can cause severe burns.
Do not touch engine while operating
or just after stopping.
Hot Parts!
Engine components can get
extremely hot from operation. To
prevent severe burns, do not
touch these areas while the
engine is running - or immediately
after it is turned off. Never operate
the engine with heat shields or
guards removed.
WARNING
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1.1
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 1
Safety and General Information
WARNING
Explosive Fuel can cause fires and
severe burns.
Stop engine before filling fuel tank.
Explosive Fuel!
Gasoline is extremely flammable
and its vapors can explode if
ignited. Store gasoline only in
approved containers, in well
ventilated, unoccupied buildings,
away from sparks or flames. Do not
fill the fuel tank while the engine is
hot or running, since spilled fuel
could ignite if it comes in contact
with hot parts or sparks from
ignition. Do not start the engine
near spilled fuel. Never use
gasoline as a cleaning agent.
WARNING
WARNING WARNING
Carbon Monoxide can cause
severe nausea, fainting or death.
Do not operate engine in closed or
confined area.
Lethal Exhaust Gases!
Engine exhaust gases contain
poisonous carbon monoxide.
Carbon monoxide is odorless,
colorless, and can cause death if
inhaled. Avoid inhaling exhaust
fumes, and never run the engine
in a closed building or confined
area.
WARNING
Hot liquid can cause severe burns.
Do not loosen radiator cap while
engine is operating or warm to the
touch.
Explosive Gas can cause fires and
severe acid burns.
Charge battery only in a well
ventilated area. Keep sources of
ignition away.
Explosive Gas!
Batteries produce explosive
hydrogen gas while being
charged. To prevent a fire or
explosion, charge batteries only in
well ventilated areas. Keep
sparks, open flames, and other
sources of ignition away from the
battery at all times. Keep batteries
out of the reach of children.
Remove all jewelry when servicing
batteries.
Before disconnecting the negative
(-) ground cable, make sure all
switches are OFF. If ON, a spark
will occur at the ground cable
terminal which could cause an
explosion if hydrogen gas or
gasoline vapors are present.
Cleaning Solvents can cause
severe injury or death.
Use only in well ventilated areas
away from ignition sources.
Flammable Solvents!
Carburetor cleaners and solvents
are extremely flammable. Keep
sparks, flames, and other sources
of ignition away from the area.
Follow the cleaner manufacturer’s
warnings and instructions on its
proper and safe use. Never use
gasoline as a cleaning agent.
1.2
Hot Liquid!
The liquid coolant can get extremely
hot from operation. T urning the
radiator cap when the engine is hot
can allow steam and scalding liquid
to blow out and burn you severely .
Shut off machine. Only remove
radiator cap when cool enough to
touch with bare hands. Slowly
loosen cap to first stop to relieve
pressure before removing
completely .
CAUTION
Electrical Shock can cause injury.
Do not touch wires while engine is
running.
Electrical Shock!
Never touch electrical wires or
components while the engine is
running. They can be sources of
electrical shock.
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Engine Identification Numbers
When ordering parts, or in any communication
involving an engine, always give the Model,
Specification, and Serial Numbers, including letter
suffixes if there are any.
The engine identification numbers appear on a decal,
or decals, affixed to the engine. The primary location is
on the side of the flywheel cover. See Figure 1-1.
Placement may vary due to OEM requirements and
specific options involved. An explanation of these
numbers is shown in Figure 1-2.
Section 1
Safety and General Information
1
Identification Decal
Figure 1-1. Engine Identification Decal Location.
A. Model No.
Liquid Cooled
Horizontal Crankshaft
Numerical Designation
B. Spec. No.
Engine Model
Model
LH630
LH685
LH750
LH760
C. Serial No.
Year Manufactured Code
Code Year
31 2001
32 2002
33 2003
34 2004
Figure 1-2. Explanation of Engine Identification Numbers.
L H 685 S
Version Code
S = Electric Start
LH685-0001
First spec written
in this model series
31 05810334
Factory Code
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1.3
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 1
Safety and General Information
Oil Recommendations
Using the proper type and weight of oil in the
crankcase is extremely important. So is checking oil
daily and changing oil regularly . Failure to use the
correct oil, or using dirty oil, causes premature engine
wear and failure.
Oil T ype
Use high-quality detergent oil of API (American
Petroleum Institute) Service Class SG, SH, SJ or
higher. Select the viscosity based on the air
temperature at the time of operation as shown in the
following table.
**
*Use of synthetic oil having 5W-20 or 5W-30 rating is
acceptable, up to 4°C (40°F).
**Synthetic oils will provide better starting in extreme cold
below -23°C (-10°F).
NOTE: Using other than service class SG, SH, SJ or
higher oil or extending oil change intervals
longer than recommended can cause engine
damage.
A logo or symbol on oil cont ainers identifies the API
service class and SAE viscosity grade. See Figure 1-3.
*
Refer to Section 6 - “Lubrication System” for detailed
procedures on checking the oil, changing the oil and
changing the oil filter.
Coolant Recommendations
Use equal parts of ethylene glycol and water only.
Distilled or deionized water is recommended,
especially in areas where the water contains a high
mineral content. Propylene glycol based antifreeze is
not recommended.
This mixture will provide protection from -37°C (-34°F)
to 108°C (226°F). For protection and use outside the
indicated temperature limits, follow the antifreeze
manufacturer's instructions on the container , but do not
exceed 70% antifreeze.
DO NOT use antifreeze with stop-leak additive(s), or
put any other additives in the cooling system.
Fuel Recommendations
WARNING: Explosive Fuel!
Gasoline is extremely flammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or flames. Do not fill the fuel tank
while the engine is hot or running, since spilled fuel
could ignite if it comes in contact with hot parts or
sparks from ignition. Do not start the engine near
spilled fuel. Never use gasoline as a cleaning agent.
General Recommendations
Purchase gasoline in small quantities and store in
clean, approved containers. A cont ainer with a capacity
of 2 gallons or less with a pouring spout is
recommended. Such a container is easier to handle
and helps eliminate spillage during refueling.
Figure 1-3. Oil Container Logo.
1.4
Do not use gasoline left over from the previous
season, to minimize gum deposits in your fuel system
and to ensure easy starting.
Do not add oil to the gasoline.
Do not overfill the fuel tank. Leave room for the fuel to
expand.
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Section 1
Safety and General Information
Fuel Type
For best results, use only clean, fresh, unleaded
gasoline with a pump sticker octane rating of 87 or
higher. In countries using the Research method, it
should be 90 octane minimum.
Unleaded gasoline is recommended, as it leaves fewer
combustion chamber deposits. Leaded gasoline may
be used in areas where unleaded is not available and
exhaust emissions are not regulated. Be aware,
however, that the cylinder head will require more
frequent service.
Gasoline/Alcohol blends
Gasohol (up to 10% ethyl alcohol, 90% unleaded
gasoline by volume) is approved as a fuel for Kohler
engines. Other gasoline/alcohol blends are not
approved.
Gasoline/Ether blends
Methyl Tertiary Butyl Ether (MTBE) and unleaded
gasoline blends (up to a maximum of 15% MTBE by
volume) are approved as a fuel for Kohler engines.
Other gasoline/ether blends are not approved.
Periodic Maintenance
WARNING: Accident al Starts!
Disabling engine. Accidental starting can cause severe injury or death. Before working on the engine or
equipment, disable the engine as follows: 1) Disconnect the spark plug lead(s). 2) Disconnect negative (-) battery
cable from battery .
Maintenance Schedule
These required maintenance procedures should be performed at the frequency stated in the table.
They should also be included as part of any seasonal tune-up.
1
Maintenance RequiredFrequency
• Fill fuel tank.
• Check oil level.
Daily or Before
Starting Engine
Every 100 Hours
Annually or
Every 200 Hours
Every 250 Hours
Annually or
Every 500 Hours
Every 2 Y ears or
Every 1000 Hours
1
Perform these maintenance procedures more frequently under extremely dusty, dirty conditions.
• Check coolant level.
• Check air cleaner for dirty1, loose, or damaged parts.
• Check the screen, radiator, and cooling areas, clean as
necessary1.
• Clean and check cooling areas1.
• Replace fuel filter.
• Change oil and oil filter (more frequently under severe
conditions).
• Check spark plug condition and gap.
• Replace spark plugs.
• Change engine coolant.
Refer to:
Section 5
Section 6
Section 7
Section 4
Section 7
Section 7
Section 5
Section 6
Section 8
Section 4• Replace air cleaner element and check inner element1.
Section 8
Section 7
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1.5
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 1
Safety and General Information
Storage
If the engine will be out of service for two months or
more, use the following storage procedure:
1. Clean the exterior surfaces of the radiator and
engine.
2. Change the oil and filter while the engine is still
warm from operation. See “Change Oil and Filter”
in Section 6.
3. The coolant (antifreeze) mixture should be in
good condition and tested to guard against
freezing in cold temperatures. The recommended
equal parts mixture will normally provide
protection down to temperatures of -37°C
(-34°F). If storage temperatures will fall below
this, the cooling system should be drained. A note
should then be attached to the equipment and/or
engine as a reminder to refill the cooling system
before starting.
4. The fuel system must be completely emptied, or
the gasoline must be treated with a stabilizer to
prevent deterioration. If you choose to use a
stabilizer , follow the manufacturer’s
recommendations, and add the correct amount
for the capacity of the fuel system. Fill the fuel
tank with clean, fresh gasoline. Run the engine for
2-3 minutes to get stabilized fuel into the
carburetor. Close fuel shut-of f valve when unit is
being stored or transported.
To empty the system, run the engine until the tank
and system are empty .
5. Remove the spark plugs. Add one tablespoon of
engine oil into each spark plug hole. Install plugs,
but do not connect the plug leads. Crank the
engine two or three revolutions.
6. Store the engine in a clean, dry place.
1.6
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Section 1
Safety and General Information
Fuel Pump
23
Rain Cap Removal
(.906)
C
Mounting Hole
L
Flywheel End
440.00
(17.323)
2X 184.20
(7.252)
458.49
(18.051)
Overall
C
Mounting Hole
L
127.90
(5.035)
622.54
(24.509)
Overall without Rain Cap
673.70
(26.524)
Overall
Optional Oil Fill
152.08
(5.987)
PTO Side
Oil
Drain
143.25
(5.640)
38.00
(1.496)
175.41
(6.906)
C
Mounting Hole "A"
L
Oil Filter Side
1
119.78
Fill
431.61
(16.992)
(4.716)
39.00
(1.535)
Oil Fill
89.00
(3.504)
Mounting Holes
C
Mounting Hole "A"
L
Starter Side
Air Intake Optional Orientation
583.30
(22.965)
490.74
(19.320)
Center of Air Intake
Engine Mounting Surface
120.96
(4.762)
Coolant
Overflow
38.00
(1.496)
C
Oil Drain Plug
L
238.61
(9.394)
Figure 1 -4. Typical Engine Dimensions.
2X 297.47
(1.711)
Exhaust Ports
101.60
(4.000)
Option
112.92
(4.446)
4.00
(.157)
Mounting Surface
Pilot
155.58
(6.125)
4X 45°
50.99
(2.007)
Mounting Hole "A"
1/4 Inch Square Key
5/8-18 UNF Thread
7/16-20 Thread Option
36.50
(1.437)
C
L
2X 60°
2X 45°
4X 3/8-16 UNC-2B Inch
Oil Filter
299.00
(11.77)
235.19
(9.259)
28.575
Option
(1.125)
142.88 Bolt Circle
(5.625)
15.70 Oil Filter Removal
(.618)
Bolt Circle 197.00
4x 7/16-14 UNC-2B Inch
177.80 Pilot
(7.000)
(7.756)
Top View
Dimensions in millimeters.
Inch equivalents shown in ().
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1.7
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 1
Safety and General Information
General Specifications
Power (@ 3600 RPM, corrected to SAE J1995)
LH630 ..............................................................Maximum ............. 16.4 kW (22 HP)
LH685 ..............................................................Maximum ............. 18.6 kW (25 HP)
LH750 ..............................................................Maximum ............. 20.1 kW (27 HP)
LH760 ..............................................................Maximum ............. 21.6 kW (29 HP)
Peak Torque
LH630 (@ 2200 RPM).................................................................... 48.0 N·m (35.4 ft. lb.)
LH685 (@ 2200 RPM).................................................................... 54.3 N·m (40.1 ft. lb.)
LH750 (@ 2200 RPM).................................................................... 61.0 N·m (45 ft. lb.)
LH760 (@ 2600 RPM).................................................................... 61.7 N·m (45.5 ft. lb.)
Bore
LH630 ............................................................................................ 77 mm (3.03 in.)
LH685 ............................................................................................ 80 mm (3.15 in.)
LH750, LH760 ................................................................................ 83 mm (3.3 in.)
Stroke
LH630, LH685 ................................................................................ 67 mm (2.64 in.)
LH750, LH760 ................................................................................ 69 mm (2.7 in.)
1
Recommended..... 13.9 kW (18.7 HP)
Recommended..... 15.9 kW (21.3 HP)
Recommended..... 17.1 kW (22.9 HP)
Recommended..... 18.4 kW (24.7 HP)
Displacement
LH630 ............................................................................................ 624 cc (38.1 cu. in.)
LH685 ............................................................................................ 674 cc (41.1 cu. in.)
LH750, LH760 ................................................................................ 748 cc (45.6 cu. in.)
Compression Ratio
LH630, LH685 .................................................................................8.5:1
LH750, LH760 .................................................................................8.7:1
Dry Weight
LH630, LH685, LH750 ................................................................... 51.7 kg (114 lb.)
LH760 ............................................................................................ 52.6 kg (1 16 lb.)
Oil Capacity (with filter)
LH630, LH685, LH750 ................................................................... 1.9 L (2.0 U.S. qt.)
LH760 ............................................................................................ 2.0 L (2.1 U.S. qt.)
Coolant Capacity (equal parts of water and ethylene glycol)................. 2.0 L (2.18 U.S. qt.)
Angle of Operation - Maximum (at full oil level) All Directions............... 20°
Camshaft
End Play (With Shim) ........................................................................... 0.076/0.127 mm (0.0030/0.0050 in.)
Running Clearance............................................................................... 0.025/0.063 mm (0.0010/0.0025 in.)
1
V alues are in Metric units. Values in parentheses are English equivalents. Lubricate threads with engine oil prior
to assembly .
NOTE: All listed dimensions and tolerances are measured at 20°C (68°F).
1.8
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Safety and General Information
Camshaft cont.
Bore I.D.
New................................................................................................ 20.000/20.025 mm (0.7874/0.7884 in.)
Max. Wear Limit............................................................................. 20.038 mm (0.7889 in.)
Camshaft Bearing Surface O.D.
New................................................................................................ 19.962/19.975 mm (0.7859/0.7864 in.)
Max. Wear Limit............................................................................. 19.959 mm (0.7858 in.)
Carburetor and Intake Manifold
Intake Manifold Fastener Torque (torque in 2 increment s).................... 7.4, 9.9 N·m (66, 88 in. lb.)
Carburetor Mounting Fastener Torque.................................................. 9.9 N·m (88 in. lb.)
Connecting Rod
Cap Fastener Torque (torque in increments) ........................................ 11.3 N·m (100 in. lb.)
Connecting Rod-to-Crankpin Running Clearance
New................................................................................................ 0.043/0.068 mm (0.0016/0.0026 in.)
Max. Wear Limit............................................................................. 0.083 mm (0.0032 in.)
Section 1
1
Connecting Rod-to-Crankpin Side Clearance ....................................... 0.26/0.63 mm (0.0102/0.0248 in.)
Connecting Rod-to-Piston Pin Running Clearance ............................... 0.015/0.028 mm (0.0006/0.001 1 in.)
Piston Pin End I.D.
New................................................................................................ 17.015/17.023 mm (0.6699/0.6702 in.)
Max. Wear Limit............................................................................. 17.036 mm (0.6707 in.)
Crankcase
Governor Cross Shaft Bore I.D.
New................................................................................................ 8.025/8.075 mm (0.3159/0.3179 in.)
Max. Wear Limit............................................................................. 8.088 mm (0.3184 in.)
Breather Cover Fastener Torque ........................................................ 10.7 N·m (95 in. lb.) Into new as-cast hole
7.3 N·m (65 in. lb.) Into used hole
Oil Drain Plug Torque............................................................................ 13.6 N·m (120 in. lb.)
Crankshaft
End Play (free)...................................................................................... 0.070/0.590 mm (0.0028/0.0232 in.)
Crankshaft Sleeve Bearing I.D. (crankcase)
New................................................................................................ 40.974/40.987 mm (1.6131/1.6136 in.)
Max. Wear Limit............................................................................. 41.000 mm (1.6141 in.)
Crankshaft Bore (in closure plate)
New................................................................................................ 40.974/41.000 mm (1.6131/1.6141 in.)
Max. Wear Limit............................................................................. 41.038 mm (1.6156 in.)
Crankshaft Bore (in closure plate)-to-Crankshaft
Running Clearance - New .............................................................. 0.039/0.087 mm (0.0015/0.0034 in.)
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1.9
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Section 1
Safety and General Information
Crankshaft cont.
Main Bearing Journals
O.D. - New ..................................................................................... 40.913/40.935 mm (1.6107/1.6116 in.)
O.D. - Max. Wear Limit .................................................................. 40.84 mm (1.608 in.)
Max. Taper ..................................................................................... 0.022 mm (0.0009 in.)
Max. Out-of-Round ........................................................................ 0.025 mm (0.0010 in.)
Crankshaft to Sleeve Bearing (crankcase)
Running Clearance - New .............................................................. 0.039/0.0074 mm (0.0015/0.0029 in.)
Connecting Rod Journal
O.D. - New ..................................................................................... 35.955/35.973 mm (1.4156/1.4163 in.)
O.D. - Max. Wear Limit .................................................................. 35.94 mm (1.415 in.)
Max. Taper ..................................................................................... 0.018 mm (0.0007 in.)
Max. Out-of-Round ........................................................................ 0.025 mm (0.0010 in.)
Crankshaft T.I.R.
PTO End, Crank in Engine............................................................. 0.15 mm (0.0059 in.)
Entire Crank, in V-Blocks ............................................................... 0.10 mm (0.0039 in.)
Cylinder Bore
Cylinder Bore I.D.
New
LH630...................................................................................... 77.000/77.025 mm (3.0315/3.0325 in.)
LH685...................................................................................... 80.000/80.025 mm (3.1496/3.1506 in.)
LH750, LH760 ......................................................................... 83.006/83.031 mm (3.2679/3.2689 in.)
Max. Wear Limit
LH630...................................................................................... 77.063 mm (3.0340 in.)
LH685...................................................................................... 80.065 mm (3.1522 in.)
LH750, LH760 ......................................................................... 83.069 mm (3.2704 in.)
Max. Out-of-Round ........................................................................ 0.12 mm (0.0047 in.)
Max. Taper ..................................................................................... 0.05 mm (0.0020 in.)
Cylinder Head
Cylinder Head Fastener Torque (torque in 2 increments)...................... 16.9, 33.9 N·m (150, 300 in. lb.)
Max. Out-of-Flatness............................................................................ 0.076 mm (0.003 in.)
Rocker Pivot Fastener Torque .............................................................. 1 1.3 N·m (100 in. lb.)
Electric Starter
St arter Thru Bolt Torque........................................................................ 5.6-9.0 N·m (49-79 in. lb.)
St arter Mounting Screw Torque............................................................. 15.3 N·m (135 in. lb.)
St arter Brush Holder Fastener Torque .................................................. 2.5-3.3 N·m (22-29 in. lb.)
St arter Solenoid Fastener Torque ......................................................... 4.0-6.0 N·m (35-53 in. lb.)
St arter Solenoid Positive (+) Brush Lead Retaining Nut Torque ............ 8.0-11.0 N·m (71-97 in. lb.)
1.10
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Section 1
Safety and General Information
Fan/Flywheel
Rear Fan Shaft to Mounting Bracket Nut Torque .................................. 15.8 N·m (140 in. lb.)
Front Fan Assembly to Fan Shaf t Nut Toque ........................................ 15.8 N·m (140 in. lb.)
Fan/Pulley/Hub Assembly Fastener Torque .......................................... 6.8 N·m (60 in. lb.)
Flywheel Retaining Screw Torque ......................................................... 66.4 N·m (49 ft. lb.)
Lower Flywheel Cover Mounting Screw Torque .................................... 9.9 N·m (88 in. lb.)
Lower Pulley Mounting Screw Torque ................................................... 24.3 N·m (215 in. lb.)
Governor
Governor Cross Shaft to Crankcase Running Clearance...................... 0.025/0.126 mm (0.0009/0.0049 in.)
Governor Cross Shaft O.D.
New................................................................................................ 7.949/8.000 mm (0.3129/0.3149 in.)
Max. Wear Limit............................................................................. 7.936 mm (0.3124 in.)
1
Governor Gear Shaft O.D.
New................................................................................................ 5.990/6.000 mm (0.2358/0.2362 in.)
Max. Wear Limit............................................................................. 5.977 mm (0.2353 in.)
Governor Gear Shaft-to-Governor Gear Running Clearance................ 0.090/0.160 mm (0.0035/0.0063 in.)
Ignition
Sp ark Plug Type (Champion
Sp ark Plug Gap .................................................................................... 0.76 mm (0.030 in.)
Sp ark Plug Torque ................................................................................ 24.4-29.8 N·m (18-22 ft. lb.)
Ignition Module Air Gap ........................................................................ 0.2/0.3 mm (0.008/0.012 in.)
Ignition Module Fastener Torque .......................................................... 6.2 N·m (55 in. lb.) Into new as-cast hole
Rectifier-Regulator Fastener Torque..................................................... 4.0 N·m (35 in. lb.)
Muffler
Muffler Retaining Nuts Torque .............................................................. 24.4 N·m (216 in. lb.)
Oil Filter/Closure Plate
Oil Filter Torque .................................................................................... 10.4-12.7 N·m (90-110 in. lb.)
®
or equivalent) ......................................... RC14YC
4.0 N·m (35 in. lb.) Into used hole
Closure Plate Fastener Torque ............................................................. 24.4 N·m (216 in. lb.)
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1.11
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 1
Safety and General Information
Piston, Piston Rings, and Piston Pin
Piston-to-Piston Pin .............................................................................. 0.006/0.018 mm (0.0002/0.0007 in.)
Piston Pin Bore I.D.
New................................................................................................ 17.006/17.013 mm (0.6695/0.6698 in.)
Max. Wear Limit............................................................................. 17.025 mm (0.6703 in.)
Piston Pin O.D.
New................................................................................................ 16.995/17.000 mm (0.6691/0.6693 in.)
Max. Wear Limit............................................................................. 16.994 mm (0.6691 in.)
Top Compression Ring-to-Groove Side Clearance
LH630 ............................................................................................ 0.040/0.086 mm (0.0016/0.0034 in.)
LH685 ............................................................................................ 0.050/0.096 mm (0.0020/0.0038 in.)
LH750, LH760 ................................................................................ 0.014/0.041 mm (0.0005/0.0016 in.)
Middle Compression Ring-to-Groove Side Clearance
LH630 ............................................................................................ 0.040/0.086 mm (0.0016/0.0034 in.)
LH685 ............................................................................................ 0.030/0.076 mm (0.0012/0.0030 in.)
LH750, LH760 ................................................................................ 0.012/0.039 mm (0.0004/0.0015 in.)
Oil Control Ring-to-Groove Side Clearance
LH630 ............................................................................................ 0.046/0.196 mm (0.0018/0.0077 in.)
LH685 ............................................................................................ 0.046/0.196 mm (0.0018/0.0077 in.)
LH750, LH760 ................................................................................ 0.026/0.176 mm (0.0010/0.0070 in.)
Top and Middle Compression Ring End Gap
LH630
New Bore
Top Ring ............................................................................ 0.180/0.380 mm (0.0071/0.0150 in.)
Middle Ring ....................................................................... 0.250/0.450 mm (0.0098/0.0177 in.)
Used Bore (Max.) .................................................................... 0.77 mm (0.030 in.)
LH685
New Bore
Top Ring ............................................................................ 0.180/0.430 mm (0.0071/0.0169 in.)
Middle Ring ....................................................................... 0.250/0.460 mm (0.0098/0.0181 in.)
Used Bore (Max.) .................................................................... 0.80 mm (0.0315 in.)
LH750, LH760
New Bore................................................................................. 0.250/0.56 mm (0.0098/0.022 in.)
Used Bore ............................................................................... 0.94 mm (0.037 in.)
Piston Thrust Face O.D.²
LH630
New ......................................................................................... 76.967/76.985 mm (3.0302/3.0309 in.)
Max. Wear Limit ...................................................................... 76.840 mm (3.0252 in.)
LH685
New ......................................................................................... 79.963/79.981 mm (3.1481/3.1488 in.)
Max. Wear Limit ...................................................................... 79.831 mm (3.1430 in.)
LH750, LH760
New ......................................................................................... 82.973/82.991 mm (3.2666/3.2673 in.)
Max. Wear Limit ...................................................................... 82.841 mm (3.3136 in.)
²Measure 6 mm (0.236 in.) above the bottom of the piston skirt at right angles to the piston pin.
1.12
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Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 1
Safety and General Information
Piston, Piston Rings, and Piston Pin cont.
Piston Thrust Face-to-Cylinder Bore² Running Clearance
LH630 ............................................................................................ 0.014/0.057 mm (0.0005/0.0022 in.)
LH685 ............................................................................................ 0.019/0.062 mm (0.0007/0.0024 in.)
LH750, LH760 ................................................................................ 0.015/0.058 mm (0.005/0.0022 in.)
Speed Control
Speed Control Bracket Assembly Fastener Torque............................... 10.7 N·m (95 in. lb.) Into new as-cast hole
7.3 N·m (65 in. lb.) Into used hole
Stator
St ator Mounting Screw Torque.............................................................. 6.2 N·m (55 in. lb.)
Throttle/Choke Controls
Governor Control Lever Fastener Torque ............................................. 9.9 N·m (88 in. lb.)
Valve Cover/Rocker Arms
V alve Cover Fastener Torque ............................................................... 6.2 N·m (55 in. lb.)
Valves and Valve Lifters
Hydraulic V alve Lifter to Crankcase Running Clearance....................... 0.0124/0.0501 mm (0.0005/0.0020 in.)
1
Intake V alve S tem-to-Valve Guide Running Clearance ......................... 0.038/0.076 mm (0.0015/0.0030 in.)
Exhaust V alve S tem-to-Valve Guide Running Clearance ...................... 0.050/0.088 mm (0.0020/0.0035 in.)
Intake V alve Guide I.D.
New................................................................................................ 7.038/7.058 mm (0.2771/0.2779 in.)
Max. Wear Limit............................................................................. 7.134 mm (0.2809 in.)
Intake V alve Stem Diameter
New................................................................................................ 6.982/7.000 mm (0.2749/0.2756 in.)
Exhaust V alve Guide I.D.
New................................................................................................ 7.038/7.058 mm (0.2771/0.2779 in.)
Max. Wear Limit............................................................................. 7.159 mm (0.2819 in.)
Exhaust V alve Stem Diameter
New................................................................................................ 6.970/6.988 (0.2744/0.2751 in.)
V alve Guide Reamer Size
St andard......................................................................................... 7.048 mm (0.2775 in.)
0.25 mm O.S.................................................................................. 7.298 mm (0.2873 in.)
Intake V alve Lif t .................................................................................... 8.88 mm (0.3496 in.)
Exhaust V alve Lif t ................................................................................. 8.88 mm (0.3496 in.)
Nominal V alve Seat Angle..................................................................... 45°
²Measure 6 mm (0.236 in.) above the bottom of the piston skirt at right angles to the piston pin.
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1.13
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 1
Safety and General Information
General Torque Values
Metric Fastener T orque Recommendations for St andard Applications
Tightening Torque: N·m (in. lb.) + or - 20%
Property Class
Noncritical
4.8
Size
M4 1.2 (1 1) 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)
5.8
8.8
10.9
12.9
Tightening Torque: N·m (ft. lb.) + or - 20%
Fasteners
Into Aluminum
Property Class
Noncritical
4.8
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) 1 16.6 (86) 139.7 (103) 61.0 (45)
M14 58.3 (43) 76.4 (55) 131.5 (97) 184.4 (136) 219.7 (162) 94.9 (70)
5.8
8.8
10.9
12.9
Fasteners
Into Aluminum
Torque
Conversions
N·m = in. lb. x 0.1 13
N·m = ft. lb. x 1.356
in. lb. = N·m x 8.85
ft. lb. = N·m x 0.737
1.14
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Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Safety and General Information
English Fastener Torque Recommendations for Standard Applications
Section 1
Tightening Torque: N·m (in. lb.) + or - 20%
Bolts, Screws, Nuts and Fasteners
Assembled Into Cast Iron or Steel
Grade 2 Grade 5 Grade 8
Size
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) --------- --------- ---------
Grade 2 or 5
Fasteners Into
Aluminum
Tightening Torque: N·m (ft. lb.) + or - 20%
Size
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) 142.4 (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) --------5/8-11 149.2 (1 10) 244.1 (180) 352.6 (260) --------5/8-18 189.8 (140) 31 1.9 (230) 447.5 (330) --------3/4-10 199.3 (150) 332.2 (245) 474.6 (350) --------3/4-16 271.2 (200) 440.7 (325) 637.3 (470) ---------
1
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1.15
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 2
LH630, LH685, LH750, LH760
Special Tools
Section 2
Special Tools
Certain quality tools are designed to help you perform specific disassembly , rep air, and reassembly procedures.
By using tools designed for the job, you can service engines easier, faster, and safer! In addition, you’ll increase
your service capabilities and customer satisfaction by decreasing engine downtime.
Kohler special tools are handled by SPX Corp., a division of Owatonna Tool Corp. (OTC). The tools are easy to
purchase by contacting SPX/OTC by phone, fax, or mail.
Phone: 1-800-533-0492
International: 1-507-455-7223
8:00 am – 8:00 pm EST
Some special tools for this engine are:
Camshaft End Play Plate ................................................................................. KO1031
Flywheel Puller Kit ........................................................................................... NU3226
Hose Clamp Pliers........................................................................................... KO1043
V alve Guide Reamer........................................................................................ KO1026
Hydraulic Lifter Removal Tool .......................................................................... KO1044
Rocker Arm Spanner Wrench .......................................................................... (OEM 6200)
Water Manometer............................................................................................ KO1048
V acuum Gauge................................................................................................ KO3223
Cylinder Leakdown Tester................................................................................ KO3219
Ignition System Tester ..................................................................................... KO1047
Amp Meter....................................................................................................... KO3218
Inductance T achometer ................................................................................... KO3216
Camshaft Seal Protector.................................................................................. KO1070
Fax: 1-800-578-7375
1-586-578-7375
International: 1-507-455-7063
Mail: SPX Corp., OTC
28635 Mound Rd.
Warren, MI 48092-3499
2
Some of the specialty tools are shown and mentioned at various points in this manual. A complete catalog of all
available tools may be ordered under Kohler Part No. TP-2546. The tool price list is available under Kohler Part
No. TP-2547.
RTV Silicone Sealant
RTV (Room Temperature Vulcanizing) silicone
sealant is used as a gasket between the crankcase
and closure plate.
Figure 2-1. T ool Catalog and Price List.
Only oxime-based, oil resistant RTV sealants, such as
those listed below, are approved for use. Loctite
5900 and 5910 are recommended for best sealing
characteristics.
Loctite® Ultra Blue 587
Loctite® Ultra Copper
Loctite® Ultra Black 598
Loctite® 5900 (Heavy Body)
Loctite® 5910
®
Nos.
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2.1
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 2
Special Tools
Loctite® 5900 is available in a handy , easy-to-use
aerosol dispenser under Kohler Part No. 25 597 07-S.
Figure 2-3. Flywheel Holding T ool.
Figure 2-2. Loctite
25 597 07-S.
NOTE: Always use fresh sealant. Using outdated
sealant can result in leakage. The aerosol
canister has a month/year date code on the
top. The sealant is generally good for two
year from the date code.
®
Instant Gasket Aerosol
Special Tools You Can Make
Flywheel Holding T ool
Flywheel removal and reinstallation becomes a ‘‘snap’’
using a handy holding tool you can make out of a
piece of an old ‘‘junk’’ flywheel ring gear as shown in
Figure 2-3. Using an abrasive cut-off wheel, cut out a
six tooth segment of the ring gear as shown. Grind off
any burrs or sharp edges. The segment can be used in
place of a strap wrench. Invert the segment and place
it between the ignition module bosses on the #1
cylinder so that the tool teeth engage the ring gear
teeth on the flywheel. The bosses will ‘‘lock’’ the tool
and flywheel in position for loosening, tightening, or
removing with a puller.
Rocker Arm/Crankshaft Tool
If you don't have a spanner wrench to lift the rocker
arms or to turn the crankshaft, you can make a tool for
doing this out of an old junk connecting rod.
Find a used connecting rod from a 10 HP or larger
engine. Remove and discard the rod cap. If it is a
Posi-Lock rod, you will also need to remove the studs.
If it is a Command rod, you will need to grind off the
aligning steps, so the joint surface is flat. Find a 1"
long capscrew with the correct thread size to match
the threads in the connecting rod. Obtain a flat washer
with correct I.D. to slip on the capscrew and an O.D. of
approximately 1". Kohler Part No. 12 468 05-S can be
used if you don't have the right size on hand.
Assemble the capscrew and washer to the joint
surface of rod, as shown in Figure 2-4.
2.2
Figure 2-4. Rocker Arm/Crankshaf t Tool.
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Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 3
Troubleshooting
Troubleshooting Guide
When troubles occur, be sure to check the simple
causes which, at first, may seem too obvious to be
considered. For example, a starting problem could be
caused by an empty fuel tank.
Some common causes of engine troubles are listed
below. Use these to locate the causing factors.
Engine Cranks But Will Not Start
1. Empty fuel tank.
2. Fuel shut-off valve closed.
3. Dirt or water in the fuel system.
4. Clogged fuel line.
5. Sp ark plug lead(s) disconnected.
6. Key switch or kill switch in “off” position.
7. Faulty spark plugs.
8. Faulty ignition module(s).
9. Carburetor solenoid malfunction.
10. Diode in wiring harness failed in open circuit
mode.
11. Vacuum fuel pump malfunction, or oil in vacuum
hose.
12. Vacuum hose to fuel pump leaking/cracked.
13. Battery connected backwards.
14. Safety interlock system engaged.
Section 3
LH630, LH685, LH750, LH760
5. Faulty choke or throttle controls.
6. Faulty spark plugs.
7. Low compression.
8. Weak spark.
9. Fuel pump malfunction causing lack of fuel.
10. Engine overheated-cooling system problem.
Engine Will Not Crank
1. PTO drive is engaged.
2. Battery is discharged.
3. Safety interlock switch is engaged.
4. Loose or faulty wires or connections.
5. Faulty key switch or ignition switch.
6. Faulty electric starter or solenoid.
7. Seized internal engine components.
Engine Runs But Misses
1. Dirt or water in the fuel system.
2. Spark plug lead disconnected.
3. Loose wires or connections that intermittently
short the kill circuit of ignition system to ground.
4. Engine overheated-cooling system problem.
5. Faulty ignition module.
6. Faulty spark plugs.
7. Carburetor adjusted incorrectly .
8. Faulty interlock switch.
Troubleshooting
3
Engine Start s But Does Not Keep Running
1. Restricted fuel tank cap vent.
2. Dirt or water in the fuel system.
3. Faulty choke or throttle controls.
4. Loose wires or connections that short the kill
terminal of ignition module to ground.
5. Faulty cylinder head gasket.
6. Faulty carburetor.
7. V acuum fuel pump malfunction, or oil in vacuum
hose.
8. Leaking/cracked vacuum hose to fuel pump.
Engines Start s Hard
1. PTO drive is engaged.
2. Dirt or water in the fuel system.
3. Clogged fuel line.
4. Loose or faulty wires or connections.
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Engine Will Not Idle
1. Restricted fuel tank cap vent.
2. Dirt or water in the fuel system.
3. Faulty spark plugs.
4. Idle speed (RPM) adjusting screw improperly set.
5. Low compression.
6. Stale fuel and/or gum in carburetor.
7. Fuel supply inadequate.
8. Engine overheated-cooling system problem.
Engine Overheats
1. Radiator, and/or cooling system component s
clogged, restricted, or leaking.
2. Excessive engine load.
3. Low crankcase oil level.
4. Low cooling system fluid level.
5. High crankcase oil level.
3.1
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 3
Troubleshooting
Engine Overheats (cont.)
6. Lean fuel mixture.
7. Fan belt failed/off.
8. Cooling fan broken.
9. Water pump belt failed/broken.
10. Water pump malfunction.
1 1. Faulty carburetor.
Engine Knocks
1. Excessive engine load.
2. Low crankcase oil level.
3. Old or improper fuel.
4. Internal wear or damage.
5. Hydraulic lifter malfunction.
Engine Loses Power
1. Low crankcase oil level.
2. High crankcase oil level.
3. Dirty air cleaner element.
4. Dirt or water in the fuel system.
5. Excessive engine load.
6. Engine overheated. (See "Engine Overheats")
7. Faulty spark plugs.
8. Low compression
9. Exhaust restriction.
10. Low battery .
Engine Uses Excessive Amount Of Oil
1. Incorrect oil viscosity/type.
2. Clogged or improperly assembled breather.
3. Worn or broken piston rings.
4. Worn cylinder bore.
5. Worn valve stems or valve guides.
6. Crankcase overfilled.
Oil Leaks from Oil Seals, Gaskets
1. Crankcase breather is clogged or inoperative.
2. Loose or improperly torqued fasteners.
3. Piston blowby or leaky valves.
4. Restricted exhaust.
Engine Loses or Uses Coolant
1. Overheating-See "Engine Overheats".
2. External leakage-from a joint connection, or a
component of the cooling system.
3. Internal leakage-from a head gasket, or cooling
system water jacket (passage) leak.
External Engine Inspection
Before cleaning or disassembling the engine, make a
thorough inspection of its external appearance and
condition. This inspection can give clues to what might
be found inside the engine (and the cause) when it is
disassembled.
• Check for buildup of dirt and debris on the radiator,
crankcase, cooling system components, and other
external surfaces. Dirt or debris on these areas
are causes of higher operating temperatures and
overheating.
• Check for obvious fuel, oil, and coolant leaks, or
damaged components. Excessive oil leakage can
indicate a clogged or improperly assembled
breather, worn or damaged seals and gasket s, or
loose or improperly torqued fasteners. Coolant
leaks can cause higher operating temperatures
and overheating.
• Check the air cleaner assembly/components for
damage or indications of leakage.
• Check the air cleaner element and inner element.
Look for holes, tears, cracked/damaged sealing
surfaces, or other damage that could allow
unfiltered air into the engine. Also note if the
elements are dirty or clogged. These could
indicate that the engine has been underserviced.
• Check the carburetor throat for dirt. Dirt in the
throat is further indication that the air cleaner is not
functioning properly .
• Check the oil level. Note if the oil level is within the
operating range on the dipstick, or if it is low or
overfilled.
• Check the coolant level within the reservoir and in
the radiator. A low or improperly filled cooling
system can cause overheating, excessive fuel
consumption, and a lack of power.
• Check the condition of the oil. Drain the oil into a
container - the oil should flow freely . Check the
appearance (color) of the oil, and for metal chips
or foreign particles. A milky, opaque color denotes
the presence of engine coolant in the crankcase
oil.
Sludge is a natural by-product of combustion;
a small accumulation is normal. Excessive
sludge formation could indicate overrich
carburetion, weak ignition, overextended oil
change intervals or wrong weight or type of oil
was used, to name a few.
NOTE: It is good practice to drain oil at a location
away from the workbench. Be sure to
allow ample time for complete drainage.
3.2
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Section 3
Troubleshooting
Cleaning the Engine
After inspecting the external condition of the engine,
clean the engine thoroughly before disassembling it.
Also clean individual components as the 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 the manufacturer’s
instructions and safety precautions carefully.
Make sure all traces of the cleaner are removed before
the engine is reassembled and placed into operation.
Even small amounts of these cleaners can quickly
break down the lubricating properties of engine oil.
Basic Engine Tests
Crankcase Vacuum Test
A p artial vacuum should be present in the crankcase
when the engine is operating. Pressure in the
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 (see Section 2).
Complete instructions are provided in the kits.
Test the crankcase vacuum with the manometer as
follows:
1. Insert the stopper/hose into the oil fill hole. Leave
the other tube of manometer open to atmosphere.
Make sure the shut-off clamp is closed.
3. Open the clamp and note the water level in the
tube.
The level in the engine side should be a minimum
of 10.2 cm (4 in.) above the level in the open
side.
If the level in the engine side is less than
specified (low/no vacuum), or the level in the
engine side is lower than the level in the open
side (pressure), check for the conditions in the
table below .
4. Close the shut-off clamp before stopping the
engine.
Compression T est
A compression test is best performed on a warm
engine. Clean any dirt or debris away from the base of
the spark plugs before removing them. Be sure the
choke is off, and the throttle is wide open during the
test. Compression should be at least 160 psi and
should not vary more than 15% between cylinders.
Cylinder Leakdown T est
A cylinder leakdown test can be a valuable alternative
to a compression test. By pressurizing the combustion
chamber from an external air source you can
determine if the valves or rings are leaking, and how
badly .
SPX Part No. KO3219 (see Section 2) is a relatively
simple, inexpensive leakdown tester for small engines.
The tester includes a quick disconnect for attaching
the adapter hose and a holding tool.
3
2. St art the engine and run at no-load full throttle
speed (3200 to 3750 RPM).
No Crankcase Vacuum/Pressure in Crankcase
Possible Cause Solution
1. Crankcase breather clogged or inoperative.
2. Seals and/or gaskets leaking. Loose or
improperly torqued fasteners.
3. Piston blowby or leaky valves. (Confirm by
inspecting components.)
4. Restricted exhaust.
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1. Replace breather assembly (valve cover).
2. Replace all worn or damaged seals and gaskets.
Make sure all fasteners are tightened securely .
Use appropriate torque values and sequences
when necessary .
3. Recondition piston, rings, cylinder bore, valves,
and valve guides.
4. Repair/replace restricted muffler/exhaust system.
3.3
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 3
Troubleshooting
Leakdown T est Instructions
1. Run engine 3-5 minutes to warm it up.
2. Remove spark plugs, dipstick, and air filter from
engine.
3. Rotate crankshaft until piston (of cylinder being
tested) is at top dead center (TDC) of
compression stroke. You will need to hold the
engine in this position while testing. The holding
tool supplied with the tester can be used if the
PTO end of the crankshaft is accessible. Slide the
holding tool onto the crankshaft and adjust the set
screw to fit in the key slot. Install a 3/8" breaker
bar into the square hole of the holding tool, so it is
perpendicular to both the holding tool and
crankshaft PTO. If the flywheel end is more
accessible, you can use a breaker bar and socket
on the flywheel nut/screw to hold it in position. You
may need an assistant to hold the breaker bar
during testing.
Leakdown T est Results
Air escaping at oil fill tube .............................................................Defective rings, worn cylinder walls, or blown
Air escaping from exhaust outlet ..................................................Defective exhaust valve.
Air escaping from carburetor inlet.................................................Defective intake valve.
Gauge reading in ‘‘low’’ (green) zone............................................Piston rings and cylinder in good condition.
Gauge reading in ‘ ‘moderate’ ’ (yellow) zone.................................. Engine is still usable, but there is some wear
Gauge reading in ‘‘high’’ (red) zone .............................................. Rings and/or cylinder have considerable wear.
If the engine is mounted in a piece of equipment,
you may be able to hold it by clamping or wedging
a driven component. Just be certain that the
engine cannot rotate off of TDC in either direction.
4. Install the adapter hose into the spark plug hole,
but do not attach it to the tester at this time.
5. Connect an adequate air source to the tester.
6. Turn the regulator knob in the increase
(clockwise) direction until the gauge needle is in
the yellow “set” area at the low end of the scale.
7. Connect tester quick-disconnect to the adapter.
Note the gauge reading and listen for escaping air
at the carburetor intake, exhaust outlet, and oil fill/
dipstick tube.
8. Check your test results against the table below:
head gasket.
present. Customer should start planning for
overhaul or replacement.
Engine should be reconditioned or replaced.
Cooling Leakage T est
A pressure test can be performed as a simple means of
determining whether the cooling system may have a
problem. The test procedure, possible results, and
recommended corrective action are covered in Section 7.
3.4
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Air Cleaners
Air Cleaner and Air Intake System
LH630, LH685, LH750, LH760
Section 4
Air Cleaner System
Section 4
General
These engines are equipped with Kohler's heavy-duty ,
cyclonic air cleaner system. See Figure 4-1. The air
cleaner includes a high-density , pleated paper main
element (see Figure 4-2), and inner safety element
(see Figure 4-3).
Figure 4-1. Heavy-duty Air Cleaner Assembly.
4
Figure 4-3. Air Cleaner Element with Inner Element.
Air Cleaner Element Service
Every 250 hours of operation (more often under
extremely dusty or dirty conditions), replace the paper
element and cylindrical inner element. Follow these
steps:
1. Unhook the two retaining clips and remove
the end cap from the air cleaner housing. See
Figure 4-4.
Figure 4-2. Air Cleaner Element.
Figure 4-4. Removing End Cap.
2. Pull the air cleaner element out of the housing.
See Figure 4-5.
4.1
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Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 4
Air Cleaner and Air Intake System
Figure 4-5. Removing Air Cleaner Element.
3. Check the condition of the inner safety element. It
should be replaced whenever it appears dirty ,
typically every other time the main element is
replaced. Before removing it from the housing,
clean the area around the base of the inner
element, so dirt does not get into the engine. See
Figure 4-6.
6. Reinstall the end cap, so the dust ejector valve
faces down, and secure with the two retaining
clips.
Air Cleaner Components
Air Cleaner Housing/End Cap Assembly
Make sure air cleaner housing including the dust
ejector valve and the end cap is in good condition and
not cracked. The two retainer clips should positively
lock when the cap is installed.
Air Cleaner Hose
Inspect the air cleaner hose to make sure it is not
cracked, split or damaged. Check that the air cleaner
hose is securely clamped to both the air cleaner outlet
and the inlet elbow on the carburetor.
Air Cleaner Mounting Base
Make sure the base is securely fastened to the upper
valve cover screw locations and the screws securing
the clamp bracket for the air cleaner housing are
properly installed and tight.
Figure 4-6. Removing Cylindrical Inner Element.
4. The elements must be replaced when dirty . Do
not attempt to clean the elements with
pressurized air, or other means, as the element s
will be ruined. Handle new elements carefully; do
not use if the sealing surfaces are bent or
damaged. Replace any damaged or questionable
components.
5. If it is being replaced, install the new inner
element, Kohler Part No. 25 083 04-S, followed by
the canister outer element; Kohler Part No.
25 083 01-S. Slide each fully into place in the
housing.
Breather Hose
Make sure the hose is in good condition, not cracked,
and properly secured to the breather cover and
adapter fitting.
Figure 4-7. Air Cleaner Assembly.
4.2
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Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 5
LH630, LH685, LH750, LH760
Fuel System and Governor
Section 5
Fuel System and Governor
Description
The Aegis horizont al twins use two dif ferent types of
fuel systems; carbureted or electronic fuel injection
(EFI).
This section covers the standard carbureted fuel
systems. The EFI systems are covered in subsection
5B. The governor system, covered at the end of this
section, is the same for all fuel systems.
WARNING: Explosive Fuel!
Gasoline is extremely flammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or flames. Do not fill the fuel tank
while the engine is hot or running, since spilled fuel
could ignite if it comes in contact with hot parts or
sparks from ignition. Do not start the engine near
spilled fuel. Never use gasoline as a cleaning agent.
Fuel System Components
The typical carbureted fuel system and related
components include the following:
Fuel Recommendations
General Recommendations
Purchase gasoline in small quantities and store in
clean, approved containers. A container with a capacity
of 2 gallons or less with a pouring spout is
recommended. Such a container is easier to handle
and helps eliminate spillage during refueling.
• Do not use gasoline left over from the previous
season, to minimize gum deposits in your fuel
system and to ensure easy starting.
• Do not add oil to the gasoline.
• Do not overfill the fuel tank. Leave room for the
fuel to expand.
Fuel T y pe
For best results, use only clean, fresh, unleaded
gasoline with a pump sticker octane rating of 87 or
higher. In countries using the Research fuel rating
method, it should be 90 octane minimum.
5
• Fuel Tank
• In-line Fuel Filter
• Fuel Pump
• Carburetor
• Fuel Lines
Operation
The fuel from the tank is moved through the in-line
filter and fuel lines by the fuel pump. On engines not
equipped with a fuel pump, the fuel tank outlet is
located above the carburetor inlet, allowing gravity to
feed fuel to the carburetor.
Fuel then enters the carburetor float bowl and is
moved into the carburetor body . There, the fuel is
mixed with air. This fuel-air mixture is then burned in
the engine combustion chamber.
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Unleaded gasoline is recommended, as it leaves less
combustion chamber deposits. Leaded gasoline may
be used in areas where unleaded is not available and
exhaust emissions are not regulated. Be aware
however, that the cylinder head will require more
frequent service.
Gasoline/Alcohol blends
Gasohol (up to 10% ethyl alcohol, 90% unleaded
gasoline by volume) is approved as a fuel for Kohler
engines. Other gasoline/alcohol blends are not
approved.
Gasoline/Ether blends
Methyl Tertiary Butyl Ether (MTBE) and unleaded
gasoline blends (up to a maximum of 15% MTBE by
volume) are approved as a fuel for Kohler engines.
Other gasoline/ether blends are not approved.
5.1
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 5
Fuel System and Governor
Fuel Filter
Most engines are equipped with an in-line fuel filter.
Periodically inspect the filter and replace when dirty
with a genuine Kohler filter.
Troubleshooting – Fuel System Related Causes
T est Conclusion
1. Check the following:
a. Make sure the fuel tank contains clean, fresh,
proper fuel.
b. Make sure the vent in fuel tank cap is open.
c. Make sure the fuel valve is open.
d. Make sure vacuum and fuel lines to fuel
pump are secured and in good condition.
2. Check for fuel in the combustion chamber.
a. Disconnect and ground the spark plug leads.
b. Close the choke on the carburetor.
c. Crank the engine several revolutions.
d. Remove a spark plug and check for fuel at
the tip.
3. Check for fuel flow from the tank to the fuel pump.
a. Remove the fuel line from the inlet fitting of
fuel pump.
b. Hold the line below the bottom of the tank.
Open the shut-off valve (if so equipped) and
observe flow.
Fuel System T est s
When the engine starts hard, or turns over but will not
start, it is possible that the problem is in the fuel
system. To find out if the fuel system is causing the
problem, perform the following tests.
2. If there is fuel at the tip of the spark plug, fuel is
reaching the combustion chamber.
If there is no fuel at the tip of the spark plug,
check for fuel flow from the fuel tank (Test 3).
3. If fuel does flow from the line, check for faulty fuel
pump (Test 4).
If fuel does not flow from the line, check the fuel
tank vent, fuel pickup screen, in-line filter, shut-of f
valve, and fuel line. Correct any observed problem
and reconnect the line.
4. Check the operation of fuel pump.
a. Remove the fuel line from the inlet fitting of
carburetor.
b. Crank the engine several times and observe
flow.
Fuel Pump
General
These engines are equipped with either a mechanical,
or pulse style fuel pump. See Figure 5-1.
4. If fuel does flow from the line, check for faulty
carburetor. (Refer to the "Carburetor" portions of
this section.)
If fuel does not flow from the line, check for a
clogged fuel line. If the fuel line is unobstructed,
check for overfilled crankcase and/or oil in pulse
line. If none of the checks reveal the cause of the
problem, replace the pump.
Operation
Pulse Fuel Pump
Operation and pumping action is created by alternating
positive and negative pressures within the crankcase.
This pressure is transmitted to the pulse pump through
a rubber hose connected between the pump and the
crankcase. The pumping action causes the diaphragm
on the inside of the pump to pull fuel in on its own
downward stroke and to push it into the carburetor on
its upward stroke. Two check valves prevent fuel from
going backward through the pump.
5.2
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Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 5
Fuel System and Governor
Mechanical Fuel Pump
The mechanical fuel pump is built into the #2 valve
cover. The actuating arm of the pump extends down
inside the cover and contacts one of the rocker arms.
Downward movement of the rocker arm allows the
pump diaphragm to flex down, drawing in fuel. As the
rocker arm comes up, the fuel is forced out toward the
carburetor.
Pulse Fuel Pump
3. Remove the vacuum line that connects the pump
to the crankcase.
4. Install a new pump using the hex. flange screws.
NOTE: Make sure the orientation of the new
pump is consistent with the removed
pump. Internal damage may occur if
installed incorrectly .
5. Connect vacuum line between the pump and
crankcase.
6. Tighten the hex. flange screws to 2.3 N·m
(20 in. lb.).
7. Connect the fuel lines to the inlet and outlet
fittings.
Mechanical Fuel Pump
1. Disconnect the fuel lines from the inlet and outlet
fittings.
2. Clean the area and remove the four screws
securing the valve cover/pump assembly to the
cylinder head. Loosen (but do not remove) the
four valve cover screws on the opposite side.
5
Mechanical Fuel Pump
Figure 5-1. Fuel Pump Styles.
Replacing the Fuel Pump
Replacement pumps are available through your source
of supply . To replace the pulse pump follow these
steps. Note the orientation of pump before removing.
Pulse Fuel Pump
1. Disconnect the fuel lines from the inlet and outlet
fittings.
2. Remove the hex. flange screws mounting fuel
pump to support.
3. Lift the air cleaner mounting bracket up slightly
and remove the valve cover/pump assembly .
Remove and discard the old gasket.
4. Rotate the engine by hand while observing the
actuating rocker arm. Stop rotating when end of
the rocker arm is at the lowest point (spring is at
maximum compression, and valve is open).
5. Position the new gasket onto the new cover/fuel
pump assembly and install onto cylinder head.
Align the air cleaner mounting bracket holes with
the upper two valve cover screw holes
6. Install the longer screws in the upper holes
and the shorter screws in the lower holes.
Finger tighten all eight valve cover mounting
screws (four each side), then torque the screws
to 6.2 N·m (55 in. lb.) in the sequence shown in
Figure 5-2.
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5.3
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 5
Fuel System and Governor
1
Fuel Shut-Off Solenoid
Most carburetors are equipped with a fuel shut-off
3
solenoid. The solenoid has a spring loaded pin that
retracts when 12 volts is applied to the lead. When
power ceases, the spring loaded pin extends and
blocks the main jet.
Below is a simple test made with the engine off that
can determine if the solenoid is functioning properly .
Use a separate, switched 12 volt power supply to test.
4
Figure 5-2. Valve Cover Torque Sequence.
2
Carburetor
General
Engines in this series are equipped with emission
compliant fixed main jet carburetors, manufactured by
Keihin. All have self-relieving chokes for ef ficient
operation. Depending on the specifications and
application involved, most will also contain a fuel shutoff solenoid and an accelerator pump. An exploded
view of the carburetor is shown in Figure 5-7, with the
accelerator pump components shown in the inset.
Most of the following information pertains to both styles
of carburetors. Differences are noted where pertinent.
Float Circuit: Fuel level in the bowl is maintained by
the float and fuel inlet needle. The buoyant force of the
float stops fuel flow when the engine is at rest. When
fuel is being consumed, the float will drop and fuel
pressure will push the inlet needle away from the seat,
allowing more fuel to enter the bowl. When demand
ceases, the buoyant force of the float will again
overcome the fuel pressure and stop the flow.
1. Shut off the fuel and remove the solenoid from the
carburetor. When the solenoid is loosened and
removed, gas will leak out of the carburetor. Have
a container ready to catch the fuel.
2. Blow/clean off solenoid using clean, compressed
air .
CAUTION: Do this test away from any fuel
vapors to prevent an accident.
3. Attach a jumper wire with alligator clips between
the solenoid black ground lead and the ground
lead of the switched 12 volt power supply .
4. With the switched 12 volt power supply "off",
insert a 1/4" male spade terminal into the terminal
end of the red power lead. Connect the exposed
terminal to the positive (+) power supply lead/
connection.
5. Turn the power supply "on". If the pin of the
solenoid retracts, the solenoid is good. Perform
test (switch off-on) a minimum of 6 times to verify
operating performance.
Carburetor Adjustments
High Altitude Operation
When operating the engine at altitudes of 1500 m
(5000 ft.) and above, the fuel mixture tends to get
overrich. This can cause conditions such as black,
sooty exhaust smoke, misfiring, loss of speed and
power, poor fuel economy, and poor or slow governor
response.
To compensate for the effects of high altitude, a
special high altitude main jet can be installed. High
altitude jets are sold in kits which include the jet and
necessary gaskets. Refer to the Parts Manual for the
correct kit number.
5.4
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General
In compliance with government emission standards,
the carburetor is calibrated to deliver the correct air-tofuel mixture to the engine under all operating
conditions. Both the low and the high speed mixture
circuits are preestablished and cannot be adjusted.
The low idle speed (RPM) is the only adjustment
available.
NOTE: Low idle speed (RPM) adjustment should be
made only after the engine has warmed up.
Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Adjusting Low Idle Speed (RPM) Setting
1. St art the engine and run at half throttle for 5 to 10
minutes to warm up. The engine must be warm
before making final low idle speed (RPM)
adjustment. Check that the throttle and choke
plates can fully open.
2. Place the throttle control into the ‘‘idle’’ or ‘‘slow’’
position.
3. Set the low idle speed to 1200 RPM* (±75 RPM)
by turning the low idle speed adjusting screw** in
or out. Check the speed using a tachometer .
*NOTE: The actual low idle speed depends on
the application. Refer to the equipment
manufacturer’s recommendations. The
low idle speed for basic engines is 1200
RPM.
Section 5
Fuel System and Governor
5
**Some early models contained an adjusting cable
and knob attached to the adjusting screw . See
Figure 5-3.
Figure 5-3. Carburetor with Adjusting Cable on the
Low Idle Speed Adjustment Screw (Early Models).
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5.5
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