Kohler CH18-745 User Manual

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COMMAND CH18-745

HORIZONTAL CRANKSHAFT

SERVICE MANUAL

Safety and General Information

Section 1

Safety and General Information

Safety Precautions

To ensure safe operation 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.

CAUTION

Caution is used to indicate the presence of a hazard that will or can cause minor personal injury or property damage if the caution is ignored.

Section 1

CH18-745

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

1.1

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

Uncoiling Spring can cause severe injury.

Wear safety goggles or face protection when servicing retractable starter.

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

Spring Under T ension!

Retractable starters contain a powerful, recoil spring that is under tension. Always wear safety goggles when servicing retractable starters and carefully follow instructions in the "Retractable Starter" Section 7 for relieving spring tension.

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.

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 shrouding. See Figure 1-1. An explanation of these numbers is shown in Figure 1-2.

Section 1

Safety and General Information

Identification Decal

Figure 1-1. Engine Identification Decal Location.

A. Model No.

Command Engine

Horizontal Crankshaft

Numerical Designation

730 740 745

B. Spec. No.

Engine Model Code Code Model

62 CH18 64 CH20 66 CH22 (624 cc) 68 CH25 76 CH22/23 (674 cc) 78 CH26

C H 18 S

62500

Horsepower

17 = 17 HP 18 = 18 HP 20 = 20 HP 22 = 22 HP 23 = 23 HP 25 = 25 HP 26 = 26 HP

Variation of Basic Engine

Version Code

S = Electric Start

CH730-0001 CH740-0001 CH745-0001

Complete Spec Number (Incorporating Model No. with V ariation No. of Basic Spec.)

C. Serial No.

Year Manufactured Code Code Year

21 1991 22 1992 23 1993 24 1994 25 1995 26 1996 27 1997 28 1998 29 1999

Figure 1-2. Explanation of Engine Identification Numbers.

3305810334

Factory Code

Code Year

30 2000 31 2001 32 2002 33 2003 34 2004 35 2005

1.3

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 Type 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 40°F. **Synthetic oils will provide better starting in extreme cold (below -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.

NOTE: Synthetic oils meeting the listed classifications

may be used with oil changes performed at the recommended intervals. However, to allow piston rings to properly seat, a new or rebuilt engine should be operated for at least 50 hours using standard petroleum based oil before switching to synthetic oil.

A logo or symbol on oil cont ainers identifies the API service class and SAE viscosity grade. See Figure 1-3.

Fuel Recommendations

WARNING: Explosive Fuel!

Gasoline is extremely flammable and its vapors can explode if ignited. Before servicing the fuel system, make sure there are no sparks, open flames or other sources of ignition nearby as these can ignite gasoline vapors. Disconnect and ground the spark plug leads to prevent the possibility of sparks from the ignition system.

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.

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 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 less combustion chamber deposits and reduces harmful exhaust emissions. Leaded gasoline is not recommended and must not be used on EFI engines, or on other models where exhaust emissions are regulated.

Figure 1-3. Oil Container Logo.

Refer to Section 6 - “Lubrication System” for detailed procedures on checking the oil, changing the oil and changing the oil filter.

1.4

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 T ertiary 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 Instructions

Section 1

Safety and General Information

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.

Maintenance Required Refer to:Frequency

• Fill fuel tank. Section 5

Daily or Before

Starting Engine

Every 25 Hours

Every 100 Hours

Every 200 Hours Every 250 Hours

Annually or

Every 500 Hours Every 500 Hours

Every 1500 Hours

Perform these maintenance procedures more frequently under extremely dusty , dirty conditions.

Have a Kohler Engine Service Dealer perform this service.

Cleanout Kits 25 755 20-S (black) or 25 755 21-S (gold) allow cooling areas to be cleaned without removing

shrouds.

• Check oil level. Section 6

• Check air cleaner for dirty1, loose, or damaged parts. Section 4

• Check air intake and cooling areas, clean as necessary1. Section 4

• Service precleaner element1. Section 4

• Replace air cleaner element1. Section 4

• Change oil. (More frequently under severe conditions.) Section 6

• Remove cooling shrouds and clean cooling areas

• Check oil cooler fins, clean as necessary (if equipped). Section 6

• Check spark plug condition and gap. Section 8

• Change oil filter. Section 6

• Replace heavy-duty air cleaner element and check inner element1. Section 4

• Have bendix starter drive serviced2. Section 8

• Have solenoid shift starter disassembled and cleaned2. Section 8

• Have crankshaft spline lubricated2. Section 2

• Replace fuel filter1 (EFI engines). Section 5B

1,3

. Section 4

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 engine. On Electronic Fuel Injected (EFI) engines, avoid spraying water at the wiring harness or any of the electrical components.

2. Change the oil and oil filter while the engine is still warm from operation. See “Change Oil and Oil Filter” in Section 6.

3. 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 to 3 minutes to get stabilized fuel into the rest of the system. Close the fuel shut-off valve when the unit is being stored or transported.

To empty the system, run the engine until the tank and the system are empty.

4. Remove the spark plugs and add one tablespoon of engine oil into each spark plug hole. Install the spark plugs, but do not connect the plug leads. Crank the engine two or three revolutions.

5. On equipment with an EFI engine, disconnect the battery or use a battery minder to keep the battery charged during storage.

6. Store the engine in a clean, dry place.

1.5

Section 1 Safety and General Information

Dimensions in millimeters. Inch equivalents shown in ().

Figure 1-4. Typical Engine Dimensions CH Series with Standard Flat Air Cleaner.

1.6

Section 1

Safety and General Information

Dimensions in millimeters. Inch equivalents shown in ().

Figure 1-5. T ypical Engine Dimensions CH EFI Series with Heavy-Duty Air Cleaner.

1.7

Section 1 Safety and General Information

General Specifications¹

Power (@ 3600 RPM, corrected to SAE J1995)

CH18............................................................................................................................13.4 kW (18 HP)

CH20............................................................................................................................14.9 kW (20 HP)

CH22/23....................................................................................................................... 16.4 kW (22 HP)

CH25, CH730...............................................................................................................18.4 kW (25 HP)

CH26............................................................................................................................19.4 kW (26 HP)

CH740..........................................................................................................................20.1 kW (27 HP)

CH745..........................................................................................................................20.9 kW (28 HP)

Peak Torque

CH18 - @ 2200 RPM ................................................................................................... 44.4 N·m (32.8 ft. lb.)

CH20 - @ 2600 RPM ................................................................................................... 44.2 N·m (32.6 ft. lb.)

CH22/23 - @ 2200 RPM ..............................................................................................51.7 N·m (38.2 ft. lb.)

CH25, CH730 - @ 2800 RPM ...................................................................................... 54.1 N·m (39.9 ft. lb.)

CH26 - @ 2800 RPM ................................................................................................... 54.2 N·m (40.0 ft. lb.)

CH740 - @ 3000 RPM ................................................................................................. 57.9 N·m (42.7 ft. lb.)

CH745 - @ 2200 RPM ................................................................................................. 60.7 N·m (44.8 ft. lb.)

Bore

CH18, CH20, CH22 (624 cc)........................................................................................ 77 mm (3.03 in.)

CH22/23 (674 cc).........................................................................................................80 mm (3.15 in.)

CH25, CH26, CH730-745.............................................................................................83 mm (3.27 in.)

Stroke.................................................................................................................................67 mm (2.64 in.) Displacement

CH18, CH20, CH22 (624 cc)........................................................................................ 624 cc (38 cu. in.)

CH22/23 (674 cc).........................................................................................................674 cc (41 cu. in.)

CH25, CH26, CH730-745.............................................................................................725 cc (44 cu. in.) Compression Ratio

CH18, CH20, CH22/23.................................................................................................8.5:1

CH25, CH26, CH730-745.............................................................................................9.0:1 Dry Weight

CH18, CH20, CH22/23................................................................................................. 41 kg (90 lb.)

CH25, CH26, CH730-745.............................................................................................43 kg (94 lb.) Oil Capacity (with filter)

CH18, CH20, CH22/23, CH25, CH26, CH730-745 ......................................................1.9 L (2.0 U.S. qt.)

Angle of Operation - Maximum (At Full Oil Level) All Directions ......................................... 25°

Blower Housing and Sheet Metal

M5 Fasteners Torque..........................................................................................................4.0 N·m (35 in. lb.)

M6 Fasteners Torque..........................................................................................................6.8 N·m (60 in. lb.)

Rectifier-Regulator Fastener Torque...................................................................................4.0 N·m (35 in. lb.)

¹V alues are in Metric units. V alues in parentheses are English equivalents. Lubricate threads with engine oil prior

to assembly.

1.8

Section 1

Safety and General Information

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.)

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 Mounting Fastener Torque

Torque in Two Stages............................................................................ initially to 7.4 N·m (66 in. lb.)

finally to 9.9 N·m (88 in. lb.)

Carburetor Mounting Screw Torque M6 ....................................................... 6.2-7.3 N·m (55-65 in. lb.)

Adapter (for Heavy Duty Air Cleaner) Mounting Fastener Torque ................ 7.3 N·m (65 in. lb.)

Connecting Rod

Cap Fastener Torque (torque in increments)

8 mm straight shank.............................................................................. 22.7 N·m (200 in. lb.)

8 mm step-down ................................................................................... 14.7 N·m (130 in. lb.)

6 mm straight shank.............................................................................. 1 1.3 N·m (100 in. lb.)

Connecting Rod-to-Crankpin Running Clearance

New....................................................................................................... 0.030/0.055 mm (0.0012/0.0022 in.)

Max. Wear Limit.................................................................................... 0.070 mm (0.0028 in.)

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.

6 mm Shaft

New ................................................................................................... 6.025/6.050 mm (0.2372/0.2382 in.)

Max. Wear Limit................................................................................. 6.063 mm (0.2387 in.)

8 mm Shaft

New ................................................................................................... 8.025/8.075 mm (0.3159/0.3179 in.)

Max. Wear Limit................................................................................. 8.088 mm (0.3184 in.)

Breather Cover Fastener Torque ................................................................. 7.3 N·m (65 in. lb.)

Oil Drain Plug T orque ................................................................................... 13.6 N·m (10 ft. lb.)

1.9

Section 1 Safety and General Information

Closure Plate

Closure Plate Fastener T orque .............................................................. 24.4 N·m (216 in. lb.)

Crankshaft

End Play (Free) .................................................................................... 0.070/0.590 mm (0.0028/0.0230 in.)

End Play (With Thrust Bearing Components) ....................................... 0.070/0.270 mm (0.0028/0.0100 in.)

Except CH25 Engines Below Serial No. 2403500008 .................... 0.050/0.750 mm (0.0020/0.0295 in.)

Crankshaft Bore (In Crankcase)

New................................................................................................ 40.965/41.003 mm (1.6128/1.6143 in.)

Max. Wear Limit ............................................................................. 41.016 mm (1.6148 in.)

Crankshaft to Sleeve Bearing (Crankcase)

Running Clearance - New................................................................ 0.03/0.09 mm (0.0012/0.0035 in.)

Crankshaft Bore (In Closure Plate) - New .............................................. 40.987/40.974 mm (1.6136/1.6131 in.) Crankshaft Bore (In Closure Plate)-to-Crankshaft

Running Clearance - New .............................................................. 0.039/0.074 mm (0.0015/0.0029 in.)

Flywheel End Main Bearing Journal

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.) Closure Plate End Main Bearing Journal

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.) 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............................................................. 0.279 mm (0.0110 in.)

Entire Crank, in V-Blocks ............................................................... 0.10 mm (0.0039 in.)

Cylinder Bore

Cylinder Bore I.D.

New - CH18, CH20, CH22 (624 cc) ............................................... 77.000/77.025 mm (3.0315/3.0325 in.)

New - CH22/23 (674 cc)................................................................. 80.000/80.025 mm (3.1496/3.1506 in.)

New - CH25, CH26, CH730-745 .................................................... 82.988/83.013 mm (3.2672/3.2682 in.)

Max. Wear Limit - CH18, CH20, CH22 (624 cc)............................. 77.063 mm (3.0340 in.)

Max. Wear Limit - CH22/23 (674 cc).............................................. 80.065 mm (3.1522 in.)

Max. Wear Limit - CH25, CH26, CH730-745.................................. 83.051 mm (3.2697 in.)

Max. Out-of-Round ........................................................................ 0.12 mm (0.0047 in.)

Max. Taper ..................................................................................... 0.05 mm (0.0020 in.)

1.10

Safety and General Information

Cylinder Head

Cylinder Head Fastener T orque

Hex. Flange Nut - Torque in T wo Stages.......................................... initially to 16.9 N·m (150 in. lb.)

finally to 33.9 N·m (300 in. lb.)

Head Bolt - Torque in Two S t ages .................................................. initially to 22.6 N·m (200 in. lb.)

finally to 41.8 N·m (370 in. lb.)

Max. Out-of-Flatness............................................................................ 0.076 mm (0.003 in.)

Rocker Arm Screw T orque.................................................................... 11.3 N·m (100 in. lb.)

Fan/Flywheel

Fan Fastener Torque ............................................................................ 9.9 N·m (88 in. lb.)

Flywheel Retaining Screw Torque......................................................... 66.4 N·m (49 ft. lb.)

Governor

Governor Cross Shaft-to-Crankcase Running Clearance

6 mm Shaft .................................................................................... 0.013/0.075 mm (0.0005/0.0030 in.)

8 mm Shaft .................................................................................... 0.025/0.126 mm (0.0009/0.0049 in.)

Section 1

Governor Cross Shaft O.D.

6 mm Shaft

New ............................................................................................ 5.975/6.012 mm (0.2352/0.2367 in.)

Max. Wear Limit.......................................................................... 5.962 mm (0.2347 in.)

8 mm Shaft

New ............................................................................................ 7.949/8.000 mm (0.3129/.3149 in.)

Max. Wear Limit.......................................................................... 7.936 mm (0.3124 in.)

Governor Gear Shaft-to-Governor Gear Running Clearance................ 0.015/0.140 mm (0.0006/0.0055 in.)

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 Lever Nut Torque .................................................................. 6.8 N·m (60 in. lb.)

Ignition

Sp ark Plug Type (Champion® or Equivalent)......................................... RC12YC or Platinum 3071

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 ........................................................................ 0.28/0.33 mm (0.01 1/0.013 in.)

Ignition Module Fastener Torque .......................................................... 4.0-6.2 N·m (35-55 in. lb.)

Speed Sensor Air Gap (EFI engines) .................................................... 1.250/1.750 mm (0.049/0.068 in.)

1.11

Section 1 Safety and General Information

Muffler

Muffler Retaining Nut Torque.................................................................. 24.4 N·m (216 in. lb.)

Oil Filter

Oil Filter Torque .................................................................................... 10.4-12.7 N·m (90-1 10 in. lb.)

Oil Cooler

Oil Cooler/Adapter Nipple Torque ......................................................... 27 N·m (20 ft. lb.)

Piston, Piston Rings, and Piston Pin

Piston-to-Piston Pin Running Clearance............................................... 0.006/0.017 mm (0.0002/0.0007 in.)

Piston Pin Bore I.D.

New................................................................................................ 17.006/17.012 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

CH18, CH20, CH22 (624 cc).......................................................... 0.040/0.080 mm (0.0016/0.0031 in.)

CH22/23 (674 cc)........................................................................... 0.030/0.076 mm (0.0012/0.0030 in.)

CH25, CH26, CH730-745............................................................... 0.025/0.048 mm (0.0010/0.0019 in.)

Middle Compression Ring-to-Groove Side Clearance

CH18, CH20, CH22 (624 cc).......................................................... 0.040/0.080 mm (0.0016/0.0031 in.)

CH22/23 (674 cc)........................................................................... 0.030/0.076 mm (0.0012/0.0030 in.)

CH25, CH26, CH730-745............................................................... 0.015/0.037 mm (0.0006/0.0015 in.)

Oil Control Ring-to-Groove Side Clearance

CH18, CH20, CH22 (624 cc).......................................................... 0.060/0.202 mm (0.0024/0.0080 in.)

CH22/23 (674 cc)........................................................................... 0.046/0.196 mm (0.0018/0.0077 in.)

CH25, CH26, CH730-745............................................................... 0.026/0.176 mm (0.0010/0.0070 in.)

Top and Center Compression Ring End Gap

New Bore - CH18, CH20, CH22 (624 cc) ....................................... 0.25/0.45 mm (0.0098/0.0177 in.)

New Bore - CH22 (674 cc) ............................................................. 0.18/0.46 mm (0.0071/0.0181 in.)

New Bore - CH25, CH26, CH730-745............................................ 0.25/0.56 mm (0.0100/0.0224 in.)

Used Bore (Max.) - CH18, CH20, CH22 (624 cc)........................... 0.77 mm (0.030 in.)

Used Bore (Max.) - CH22/23 (674 cc)............................................ 0.80 mm (0.0315 in.)

Used Bore (Max.) - CH25, CH26, CH730-745 ............................... 0.94 mm (0.037 in.)

Piston Thrust Face O.D.²

New - CH18, CH20, CH22 (624 cc) ............................................... 76.967/76.985 mm (3.0302/3.0309 in.)

New - CH22/23 (674 cc)................................................................. 79.963/79.979 mm (3.1481/3.1488 in.)

New - CH25, CH26, CH730-745 .................................................... 82.986 mm (3.3194 in.)

Max. Wear Limit - CH18, CH20, CH22 (624 cc)............................. 76.840 mm (3.0252 in.)

Max. Wear Limit - CH22 (674 cc)................................................... 79.831 mm (3.1430 in.)

Max. Wear Limit - CH25, CH26, CH730-745.................................. 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

Safety and General Information

Piston, Piston Rings, and Piston Pin cont.

Piston Thrust Face-to-Cylinder Bore² Running Clearance

New - CH18, CH20, CH22 (624 cc) ............................................... 0.014/0.057 mm (0.0005/0.0022 in.)

New - CH22/23 (674 cc)................................................................. 0.021/0.062 mm (0.0008/0.0024 in.)

New - CH25, CH26, CH730-745 .................................................... 0.001/0.045 mm (0.039/0.0018 in.)

Speed Control Bracket

Fastener T orque ................................................................................... 7.3-10.7 N·m (65-95 in. lb.)

Starter Assembly

Thru Bolt Torque

UTE/Johnson Electric, Eaton (Inertia Drive) ................................... 4.5-5.7 N·m (40-50 in. lb.)

Nippondenso (Solenoid Shift)......................................................... 4.5-7.5 N·m (40-84 in. lb.)

Delco-Remy (Solenoid Shift) .......................................................... 5.6-9.0 N·m (49-79 in. lb.)

Mounting Screw Torque (All)................................................................. 15.3 N·m (135 in. lb.) Brush Holder Mounting Screw Torque

Delco-Remy Starter........................................................................ 2.5-3.3 N·m (22-29 in. lb.)

Solenoid (Starter)

Mounting Hardware Torque

Nippondenso Starter .......................................................................6.0-9.0 N·m (53-79 in. lb.)

Delco-Remy Starter.........................................................................4.0-6.0 N·m (35-53 in. lb.) Nut, Positive (+) Brush Lead Torque

Nippondenso Starter .......................................................................8.0-12.0 N·m (71-106 in. lb.)

Delco-Remy Starter.........................................................................8.0-11.0 N·m (71-97 in. lb.)

Section 1

Stator

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

V alve Cover Fastener Torque

Gasket Style Cover ........................................................................ 3.4 N·m (30 in. lb.)

Black O-Ring Style Cover

w/Shoulder Screws.................................................................... 5.6 N·m (50 in. lb.)

w/Flange Screws and Spacers .................................................. 9.9 N·m (88 in. lb.)

Brown O-Ring Style Cover w/Integral Metal Spacers...................... 9.9 N·m (88 in. lb.)

Valves and Valve Lifters

Hydraulic V alve Lifter to Crankcase Running Clearance........................0.0241/0.0501 mm (0.0009/0.0020 in.)

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............................................................................. 7.135 mm (0.2809 in.)

1.13

Section 1 Safety and General Information

Valves and Valve Lifters cont.

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.)

V alve Guide Reamer Size

Standard......................................................................................... 7.048 mm (0.2775 in.)

0.25 mm O.S.................................................................................. 7.298 mm (0.2873 in.)

Intake V alve Minimum Lif t..................................................................... 8.07 mm (0.3177 in.)

Exhaust V alve Minimum Lift.................................................................. 8.07 mm (0.3177 in.)

Nominal V alve Seat Angle ..................................................................... 45°

General Torque Values

Metric Fastener T orque Recommendations for St andard Applications

Tightening Torque: N·m (in. lb.) + or - 10%

Property Class

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

Noncritical

Fasteners

Into Aluminum

Tightening Torque: N·m (ft. lb.) + or - 10%

Property Class

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) 116.6 (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

Noncritical

Fasteners

Into Aluminum

1.14

Safety and General Information

English Fastener T orque Recommendations for St andard 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 (1 15) 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 (110) 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) ---------

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

1.15

Section 1 Safety and General Information

1.16

Section 2

Special Tools

CH18-745

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 Endplay Plate........................................................................................ KO1031

Flywheel Strap W rench ......................................................................................... NU10357

Flywheel Puller Kit................................................................................................. NU3226

Rocker Arm Spanner Wrench................................................................................ OEM6200

V alve Guide Reamer ............................................................................................. KO1026

Water Manometer ................................................................................................. KO1048

Cylinder Leakdown Tester ..................................................................................... KO3219

Ignition System Tester ........................................................................................... KO1046

Hydraulic Lifter Removal/Reinstallation Tool.......................................................... KO1044

St arter Service Kit ................................................................................................. KO3226

St arter Retaining Ring Tool.................................................................................... 25 761 18-S

V acuum Gauge ..................................................................................................... KO3223

Tachometer (Digital Inductive) ............................................................................... KO3216

Sp ark Advance Module (SAM) Tester ..................................................................... KO3222

Rectifier-Regulator T ester ....................................................................................... KO3221

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

Electronic Fuel Injection (EFI) Service T ools

EFI Service Kit ...................................................................................................... KO3217

Gauge Assembly ............................................................................................... KO3217-4

Pliers................................................................................................................. KO3217-5

Circuit Tester ..................................................................................................... KO3217-6

Jumper Plug, Red (for metal cased ECU) ......................................................... KO3217-7

Tee Valve Assembly .......................................................................................... KO3217-8

Jumper Plug, Blue (for plastic cased ECU) ....................................................... KO3217-9

Some of the specialty tools are shown and mentioned at various points in this manual. A complete catalog of available tools may be ordered under Kohler Part No. TP-2546. The tool price list is available under Kohler Part No. TP-2547.

2.1

Section 2 Special Tools

Figure 2-1. Tool Catalog and Price List.

Special Tools You Can Make

Flywheel Holding T ool

Flywheel removal and reinstallation becomes a “snap” using a handy holding tool which can be made out of an old “junk” flywheel ring gear as shown in Figure 2-2. 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 bosses on the crankcase so that the tool teeth engage the flywheel ring gear teeth. The bosses will “lock” the tool and flywheel in position for loosening, tightening or removing with a puller.

Find a used connecting rod from a 10 HP or larger engine. Remove and discard the rod cap. If it is a PosiLock 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 in. long capscrew with the correct thread size to match the threads in the connecting rod. Obtain a flat washer with the correct I.D. to slip on the capscrew and an O.D. of approximately 1 in. 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 the rod, as shown in Figure 2-3.

Figure 2-3. Rocker Arm/Crankshaf t Tool.

Cylinder Leakdown Tester

A Cylinder Leakdown Tester (SPX Part No. KO3219 formerly Kohler 25 761 05-S) is a valuable alternate to a compression test on these engines. See Figure 2-4. By pressurizing the combustion chamber from an external air source, this tool can determine if valves or rings are leaking. Instructions for using this tester are found in Section 3 of this manual.

Figure 2-2. Flywheel Holding Tool.

Rocker Arm/Crankshaft Tool

If you don’t have a spanner wrench to lift the rocker arms or turn the crankshaft, you can make a tool for doing this out of an old junk connecting rod.

2.2

Figure 2-4. Cylinder Leakdown Tester.

RTV Silicone Sealant

RTV silicone sealant is used as a gasket between the crankcase and closure plate.

Only oxime-based, oil resistant RTV sealants, such as those listed below, are approved for use. Loctite® Nos. 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

Section 2

Special Tools

Figure 2-6. Camshaft Break-in Lubricant.

NOTE: Always use fresh sealant. Using outdated

sealant can result in leakage.

Loctite® 5900 is available in a 4 oz aerosol dispenser with replacement tips under Kohler Part No.

25 597 07-S. See Figure 2-5.

Figure 2-5. Loctite® 5900 Aerosol Dispenser .

Camshaft Break-in Lubricant

Camshaft lubricant, Kohler Part No. 25 357 14-S (V alspar ZZ613), should be used whenever a new camshaft and lifters are installed for proper break-in upon initial startup. Lubricant is included with each replacement camshaft and lifter , or may also be obtained separately in a 1/8 oz handy dispensing tube by the part number listed. See Figure 2-6.

Spline Drive Lubricant

Special spline drive crankshaft lubricant Kohler Part No. 25 357 12-S is available in a 2.8 oz tube for use on all spline drive applications. This lubricant provides proper protection against wear-related damage. See Figure 2-7.

Figure 2-7. Crankshaft Spline Drive Lubricant.

Dielectric Grease

Dielectric grease is applied to the outside of the terminal connections on the SMART -SP ARK™ ignition modules to prevent formation of a moisture path and arcing between the terminals. The chart below lists the approved dielectric greases.

Dielectric Grease

Kohler

Part No.

Vendor

Vendor No./

Description

G.E./Novaguard

Fel-Pro

G661

Lubri-Sel

25 357 11-S

---

2.3

Section 2 Special Tools

2.4

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 general common causes of engine troubles are listed below. Use these to locate the causing factors. Refer to the specific section(s) within this service manual for more detailed information.

Engine Cranks But Will Not Start

1. Empty fuel tank.

2. Fuel shut-off valve closed.

3. Poor fuel, 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. SMART-SP ARK™ malfunction (applicable models).

10. Carburetor solenoid malfunction. 1 1. Diode in wiring harness failed in open circuit mode.

12. V acuum fuel pump malfunction, or oil in vacuum hose.

13. Vacuum hose to fuel pump leaking/cracked.

14. Battery connected backwards.

Engine Start s But Does Not Keep Running

1. Restricted fuel tank cap vent.

2. Poor fuel, dirt or water in the fuel system.

3. Faulty or misadjusted 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.

9. Intake system leak.

10. Diode in wiring harness failed in open circuit mode.

Section 3

Troubleshooting

Engine Starts 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.

5. Faulty or misadjusted 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/air circulation restricted.

1 1. Quality of fuel.

12. Flywheel key sheared.

13. Intake system leak.

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. Sp ark plug lead disconnected.

3. Poor quality of fuel.

4. Faulty spark plug(s).

5. Loose wires or connections that intermittently ground the ignition kill circuit.

6. Engine overheated.

7. Faulty ignition module or incorrect air gap.

8. Carburetor adjusted incorrectly .

9. SMART-SPARK™ malfunction (applicable models).

CH18-745

3.1

Section 3 Troubleshooting

Engine Will Not Idle

1. Dirt or water in the fuel system.

2. St ale fuel and/or gum in carburetor.

3. Faulty spark plugs.

4. Fuel supply inadequate.

5. Idle speed adjusting screw improperly set.

6. Idle fuel adjusting needle improperly set (some models).

7. Low compression.

8. Restricted fuel tank cap vent.

9. Engine overheated-cooling system/air circulation problem.

Engine Overheats

1. Air intake/grass screen, cooling fins, or cooling shrouds clogged.

2. Excessive engine load.

3. Low crankcase oil level.

4. High crankcase oil level.

5. Faulty carburetor.

6. Lean fuel mixture.

7. SMART-SPARK™ malfunction (applicable models).

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.

6. Quality of fuel.

7. Incorrect grade of oil.

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.

7. Faulty spark plugs.

8. Low compression.

9. Exhaust restriction.

10. SMART-SPARK™ malfunction (applicable models). 1 1. Low battery .

12. Incorrect governor setting.

Engine Uses Excessive Amount of Oil

1. Incorrect oil viscosity/type.

2. Clogged or improperly assembled breather.

3. Breather reed broken.

4. Worn or broken piston rings.

5. Worn cylinder bore.

6. Worn valve stems/valve guides.

7. Crankcase overfilled.

8. Blown head gasket/overheated.

Oil Leaks from Oil Seals, Gaskets

1. Crankcase breather is clogged or inoperative.

2. Breather reed broken.

3. Loose or improperly torqued fasteners.

4. Piston blowby or leaky valves.

5. Restricted exhaust.

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 crankcase, cooling fins, grass screen and other external surfaces. Dirt or debris on these areas are causes of higher operating temperatures and overheating.

• Check for obvious fuel and oil leaks, and damaged components. Excessive oil leakage can indicate a clogged or improperly-assembled breather, worn/damaged seals and gaskets, or loose or improperly-torqued fasteners.

• Check the air cleaner cover and base for damage or indications of improper fit and seal.

• Check the air cleaner element. Look for holes, tears, cracked or damaged sealing surfaces, or other damage that could allow unfiltered air into the engine. Also note if the element is dirty or clogged. These could indicate that the engine has been under serviced.

3.2

• 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.

Section 3

Troubleshooting

• Check the condition of the oil. Drain the oil into a container - the oil should flow 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 overrich carburetion, weak ignition, overextended oil change interval 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.

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 partial vacuum should be present in the crankcase when the engine is operating at normal temperatures. 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 (SPX Part No. KO1048, formerly Kohler Part No. 25 761 02-S) or a vacuum gauge (SPX Part No. KO3223, formerly Kohler Part No. 25 761 22-S). Complete instructions are provided in the kits.

T o test the crankcase vacuum with the manometer:

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.

2. St art the engine and run at no-load high speed (3200 to 3750 RPM).

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 on page 3.4.

4. Close the shut off clamp before stopping the engine.

To test the crankcase vacuum with the Vacuum/ Pressure Gauge Kit (SPX Part No. KO3223):

1. Remove the dipstick or oil fill plug/cap.

2. Install the adapter into the oil fill/dipstick tube opening, upside down over the end of a small diameter dipstick tube, or directly into engine if a tube is not used.

3. Push the barbed fitting on the gauge solidly into the hole in the adapter.

4. Start the engine and bring it up to operating speed (3200-3600 RPM).

5. Check the reading on the gauge. If the reading is to the left of “0” on the gauge, vacuum or negative pressure is indicated. If the reading is to the right of “0” on the gauge, positive pressure is present.

Crankcase vacuum should be 4-10 (inches of water) If the reading is below specification, or if pressure is present, check the following table for possible causes and remedies.

3.3

Section 3 Troubleshooting

No Crankcase Vacuum/Pressure in Crankcase

Possible Cause

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.

Compression T est

Some of these engines are equipped with an automatic compression release (ACR) mechanism. Because of the ACR mechanism, it is dif ficult to obtain an accurate compression reading. As an alternative, perform a cylinder leakdown test.

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 (formerly Kohler Part No. 25 761 05-S) 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.

Leakdown T est Instructions

1. Run engine for 3-5 minutes to warm it up.

Solution

1. Disassemble breather, clean p arts thoroughly , check sealing surfaces for flatness, reassemble, and recheck pressure.

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.

onto the crankshaft. Install a 3/8" breaker bar into the hole/slot of the holding tool, so it is perpendicular to both the holding tool and crankshaft PTO. If the flywheel end is more accessible, use a breaker bar and socket on the flywheel nut/screw to hold it in position. An assistant may be needed to hold the breaker bar during testing. If the 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 that the engine cannot rotate off of TDC in either direction.

4. Install the adapter into the spark plug hole, but do not attach it to the tester at this time.

5. Connect an air source of at least 50 psi 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.

2. Remove spark plug(s) and air filter from engine.

3. Rotate the crankshaft until the piston (of cylinder being tested) is at top dead center of the compression stroke. 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. Lock the holding tool

3.4

7. Connect the tester quick-disconnect to the adapter hose while firmly holding the engine at TDC. Note the gauge reading and listen for escaping air at the carburetor intake, exhaust outlet, and crankcase breather.

8. Check your test results against the following table:

Section 3

Troubleshooting

Leakdown Test Results

Air escaping from crankcase breather ...................................................Defective rings or worn cylinder .

Air escaping from exhaust system......................................................... Defective exhaust valve.

Air escaping from carburetor .................................................................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 present. Customer should start planning for overhaul or replacement.

Gauge reading in “high” (red) zone........................................................Rings and/or cylinder have considerable

wear. Engine should be reconditioned or replaced.

3.5

Section 3 Troubleshooting

3.6

Air Cleaner and Air Intake System

Air Cleaners

Air Cleaner and Air Intake System

Section 4

CH18-745

General

Most engines are equipped with a replaceable, highdensity paper air cleaner element, surrounded by an oiled foam precleaner, and housed under a flat outer cover. This is typically referred to as the standard air cleaner assembly . See Figures 4-1 and 4-4. Some engines utilize a heavy-duty style air cleaner as shown in Figure 4-12.

Figure 4-1. Standard Air Cleaner.

Figure 4-2. Removing Latch Style Cover.

Cover

Air Cleaner Element

Precleaner

Standard Air Cleaner

Service Check the air cleaner daily or before starting the engine. Check for and correct any buildup of dirt and

debris, along with loose or damaged components. NOTE: Operating the engine with loose or damaged

air cleaner components could allow unfiltered air into the engine, causing premature wear and failure.

Figure 4-3. Removing Knob Style Cover .

Precleaner Service If so equipped, wash and reoil the precleaner every 25 hours of operation (more often under extremely dusty

or dirty conditions). To service the precleaner, perform the following steps:

1. Unhook the latches or loosen the retaining knob, and remove the cover.

2. Remove the foam precleaner from the paper air cleaner element.

4.1

Section 4 Air Cleaner and Air Intake System

3. Wash the precleaner in warm water with detergent. Rinse the precleaner thoroughly until all traces of detergent are eliminated. Squeeze out excess water (do not wring). Allow the precleaner to air dry .

4. Saturate the precleaner with new engine oil. Squeeze out all excess oil.

5. Reinstall the precleaner over the paper air cleaner element.

6. Reinstall the air cleaner cover . Secure the cover with the two latches or the retaining knob.

Element Cover

Element

Figure 4-4. Air Cleaner Components.

Wing Nut

Precleaner

Seal

Figure 4-6. Removing Elements.

Figure 4-7. Removing Rubber Seal from Bracket.

Paper Element Service (Standard Type)

Every 100 hours of operation (more often under extremely dusty or dirty conditions), replace the paper element. Follow these steps:

Figure 4-5. Removing Element Cover Wing Nut.

4.2

1. Unhook the latches or loosen the retaining knob, and remove the cover.

2. Remove the wing nut, element cover, and p aper element with precleaner (if so equipped).

3. Remove the precleaner (if so equipped) from the paper element. Service the precleaner as described in "Precleaner Service".

4. Do not wash the paper element or use pressurized air, as this will damage the element. Replace a dirty , bent, or damaged element with a genuine Kohler element. Handle new elements carefully; do not use if the sealing surfaces are bent or damaged.

Section 4

Air Cleaner and Air Intake System

5. Check the seal for any damage or deterioration. Replace as necessary . See Figure 4-7.

6. Reinstall the seal, paper element, precleaner , element cover, and wing nut.

7. Reinstall the air cleaner cover and secure with the latches or the retaining knob.

NOTE: Make sure the correct depth air cleaner

element and rubber seal are used for the engine spec involved. Some engines use a deeper or extra capacity air cleaner and a longer rubber seal.

Figure 4-8. Exploded View of St andard Air Int ake System Component s.

4.3

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