6. Apply 138–206 kPa (20–30 psi) of air pressure through the adapter hose into the cylinder to be tested. Keep the crankshaft
from rotating.
7. Test result interpretation:
Possible Cause Test Result
Leaking intake valve Air is heard leaking up through the intake manifold at the throttle body.
Leaking exhaust valve Air is heard leaking into the exhaust system.
Leaking piston or piston rings
A high volume of air leaks into the test cylinder's rocker arm cover and can be felt flowing
out of the oil fill or breather cap. (Low volume air bleed past the rings is normal.)
Engine Troubleshooting
90-8M0099748 eng DECEMBER 2015 © 2016 Mercury Marine Page 3C-13
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