Engine Compression Testing?

[Lonx]

I recently had some issue with my engine & ran a compression test which showed cylinders 1 & 4 on my CA18 held around 40psi, and cylinder 2 & 3 were at 130 - 140psi. This was a cold test but after adding a little oil to cylinder 1 it rose to 100psi.

Do you think its safe to assume, as I am at the moment, that the compression rings of cylinders 1 & 4 are broken? Or is there a particular reason why the two outer cylinders aren't getting the right compression when testing. Just wondering if there's something I'm missing, or if the engine really is just stuffed.

Tests were done with cold engine as stated, closed throttle or open throttle makes no difference to test result, and I repeated the tests a few times to be sure the results I had were accurate. Thanks for your time if you reply,

[tomee]

i was told to always do the test after the engine has been ran to operating temprature, then open throttle while testing.

then doing a wet test, to see if your numbers rose to normal fiunding out if teh rings were shot or not...

[Lonx]

Yeah I've heard and read the same as well mate. The reason is because with heat & expansion, you will get higher figures when the engine is warm & also more realistic ones considering thats the temp the engine runs at 98% of the time. I think the difference between dry & wet on the first cylinder shows the rings rather than valve leakage as the problem. I appreciate your reply, nice to know someone took the time to give their thoughts. Thanks mate,