Compression Test; Cylinder Leakdown Test; Leakdown Test Instructions; Leakdown Test Results - Kohler Courage SV470 Service Manual

Section 3
Troubleshooting

Compression Test

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 alternate, use the
leakdown test described below.

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.
The cylinder leakdown tester is a relatively simple,
inexpensive leakdown tester for small engines.
The tester includes a quick disconnect coupling 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.
3. Rotate the crankshaft until the piston is at top
dead center of the 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, align the slot with one of the
mounting holes on the PTO face, and tighten it
onto the crankshaft. Install a 3/8" breaker bar into
Air escaping from crankcase breather ................................................Defective rings or worn cylinder walls.
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
Gauge reading in high (red) zone ........................................................Rings and/or cylinder have considerable wear.
3.4
the slot of the holding tool, so it is perpendicular
to both the holding tool and crankshaft, or insert
a shoulder bolt through the slot and thread it into
the mounting hole. 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. 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 into the spark plug hole, but
do not attach it to the tester at this time.
5. Connect an adequate air source (80-100 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 (right) end of the
scale.
7. Connect the tester quick-disconnect to the
adapter. Note the gauge reading and listen for
escaping air at the carburetor inlet, exhaust
outlet, and/or crankcase breather.
8. Check your test results against the table below:

Leakdown Test Results

present. Customer should start planning for
overhaul or replacement.
Engine should be reconditioned or replaced.