Kohler COMMAND CV17-745 Service Manual page 26

Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 3
Troubleshooting
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 Test
Some of these engines are equipped with an
automatic compression release (ACR) mechanism.
Because of the ACR mechanism, it is difficult to obtain
an accurate compression reading. As an alternative,
perform a cylinder leakdown test.
Cylinder Leakdown Test
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 Test Instructions
1. Run the engine for 3-5 minutes to warm it up.
2. Remove the spark plug(s) and the 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
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.
3.4
No Crankcase Vacuum/Pressure in Crankcase
www.mymowerparts.com
Solution
1. Disassemble breather, clean parts thoroughly,
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.
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.
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 the test results against the following table: