Very nice write-up, its about time someone gave the general concept of this procedure, as it is a VERY useful diagnostic tool. *Repped*
I don't mean to nitpick, but there are some things I would like to add...
Originally Posted by
DareDevil
Compression is a process in which air or an air/fuel mixture is confined and pressed into a smaller volume within the area of an engine's cylinder.
It's actually volume, as the combustion chamber is three dimensional.
Originally Posted by
DareDevil
- Make sure the engine has been warmed up before beginning the test, to ensure that the oil has been warmed up. A cold engine will not test correctly.
- Disable the ignition module or coil.
- Insert the compression tester into one cylinder spark plug hole at a time.
- Hold the throttle to full open position to ensure the engine gets adequate air intake.
You will also want to disconnect the fuel system, and adding gas will throw off your results.
Originally Posted by
DareDevil
If the compression readings do not change, then it would indicate a timing problem between the camshaft(s) and the crankshaft of the engine.
If you add oil, and the compression doesn't increase, it doesn't necessarily mean a timing issue... it could also be a bad headgasket, or poor ring seating.