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Compression test pressure
Posted: Sun Dec 31, 2006 3:24 am
by MR2 Zig
Does any one know what the reading is that I should get when doing a compression test? In pounds per square inch ( I'm lousy at making conversions) please. Also if you have both hot and cold readings that would help. I'm asking about a stock US spec 2.5 engine (that's quite possibly worn out) 9:1 compression ratio I think.
Thanks and happy new year,
Scott
ps; i searched here and in my manual to no avail...i likely missed it entirely
Posted: Sun Dec 31, 2006 5:28 am
by Murray
Scott a range of 150 psi - 190 psi seems to be within the "norm" for the 2.5L.There are many variables which determine the average across the six cylinders such as camshaft specs carbonization etc.What is most important is the variance between cylinders.More than 10 psi difference between any two cylinders and you might want to start asking questions.
If you're using a standard compression tester it's very difficult to get a good tight connection in the sparkplug well because you're trying to tighten using a flexible hose.I'm in the process of making myself a solid tube extension which will take care of this . I know you can buy them ready-made for hemi engines.
Personally I wouldn't check cold compression because I don't know that the results are of any value ?
Posted: Sun Dec 31, 2006 4:11 pm
by MR2 Zig
Thanks Murray!
I did it with the flex hose unit and got 105 on all but #1 where it read 85. When I put oil in the cylinders all of them came up to 150 and even at that. So, most discouraging i think.
I guess i'll see if i can still get that 3.0 out of ape.
I've been having problems starting when its cold out (here cold is around freezing) and using the either to get to work.
scott