Kohler Command PRO CH749, Service Manual

Page: 26 / 154

3.2
Section 3
Troubleshooting
Engine Overheats
1. Air intake/grass screen, cooling fi ns, oil cooler, or
cooling shrouds clogged.
2. Excessive engine load.
3 Low crankcase oil level.
4. High crankcase oil level.
5. Lean air-fuel mixture.
Engine Knocks
1. Excessive engine load.
2. Low crankcase oil level.
3. Old or improper fuel.
4. Internal wear or damage.
5. Hydraulic li
ft er 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. Low ba
tt ery.
11. Incorrect governor se tt ing.
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 over
fi lled.
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
fi ns, 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
fi t and seal.

•

Check the air cleaner element. Look for holes,
tears, cracked or damaged sealing surfaces, or
other damage that could allow un
fi ltered 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 oil level. Note if the oil level is within
the operating range on the dipstick, or if it is low
or over
fi lled.

•

Check the condition of the oil. Drain the oil into
a container - the oil should
fl ow freely. Check for
metal chips and other foreign particles.
Sludge is a natural by-product of combustion; a
small accumulation is normal. Excessive sludge
formation could indicate overrich fuel se
tt ings,
weak ignition, over-extended 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
A ft er 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
.