Kohler COMMAND CH18-CH26, Service Manual

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3.2
Section 3
Troubleshooting
Engine Will Not Idle
1. Dirt or water in the fuel system.
2. Stale 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).
11. 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.
• 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.