Basic Troubleshooting
23
3. Connect tester to compressed air.
4. Adjust the regulator knob until the needle on the
gauge is in the yellow or set area of the gauge. See
Figure 2.2.
5. Connect the tester to the adapter.
NOTE: Open the valve, if equipped.
NOTE: If the engine rotates it was not at top dead center.
6. Check the reading on the gauge.
7. Compare the results to the following chart.
Leak-down Testing Results
Symptom Possible cause
Air escaping from
the breather
Worn cylinder or piston rings.
Possible blown head gasket
Air escaping from
the exhaust
Leaking exhaust valve
Air escaping from
the carburetor
Leaking intake valve
Gauge reading
low
Cylinder and piston rings are in
good condition
Gauge reading
moderate
There is some wear in the
engine, but it is still usable
Gauge reading
high
excessive wear of cylinder and/
or piston rings. Engine should
be short blocked or it could be a
blown head gasket.
Figure 2.2
Regulator
knob
Valve
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