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Old 08-16-2009, 03:23 PM   #6
RotaryDiagnostics
Compression Tester Man
 
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Quote:
Originally Posted by sen2two View Post
three even bumps is what your really looking for. so three bumps like 30/30/30 = 90. thats ok. but not great. 110 is a nice fresh motor.
Not sure where you got that information, but the compression readings per compression face are not additive. They are what they are for each face. Letting the pressure build over time is meaningless. You should be looking for 3 even bounces of like 80 psi or more. Make sure you remove the schraeder valve or hold in the button on the side of the gauge while cranking the engine. Make sure the gas pedal is held to the floor when cranking the engine.

However, you cannot really evaluate the compression readings derived from such a procedure since you do not know the engine cranking speed during the test. Get a free copy of the factory service manual and read up on compression testing. Better yet, for accurate information, have a compression test done by someone with a proper tester who know what they are doing.
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