1G Just did a compression test good results?

[cmptrphreak]

all three cylinders from the side of trans are all 85 the 4th is like 75 - 80. Is that good my car is a stock 1990 mitsubishi eclipse gsx stick

 

[oddrob]

Was the car fully warmed up? Is it a good gauge? You want to be in the 145-160 range.

 

[GritsnGravy]

just like oddrod said, it should be around 145-160. Mine on my 91 awd TSi was 150 on all cylinders. You are losing some big power if your compression is that low. Not to be an a**, but did you set it up right.

 

[Turbo Talon DL]

I've done compression tests on cold and warm engines. It was actually the warm engine that yeilded lower numbers for me, but then again it was about 30* out. I had 190+psi on all 4 cyl before my engine went to shit last summer. Service limit by Haynes is 121psi.

 

[DSM MAN]

Did you try putting some oil in it? If the compression goes back up a ton your rings are done.

 

[Defiant]

Used-up. Rebuild.

 

[DSMJim]

all three cylinders from the side of trans are all 85 the 4th is like 75 - 80. Is that good my car is a stock 1990 mitsubishi eclipse gsx stick

It sounds more to me like you screwed up the test or your compression tester is screwed up. Your compression should be around 145-160 in all cylinders. Even with a yaked motor nobody gets a consistant reading at 85 psi.

Your motor should be warm and make sure that there is a good seal around the end of the tester where it screws into the spark plug hole. Chances are your compression is alright but your not doing the test right or your tester is smoked. I would try it again with a new tester and I'll bet you see some different results.

 

[cmptrphreak]

How do u guys do the test. I took out all the plugs and then tested one by one while someone was in the car cranking it over a bit.

 

[Game Over]

One plug at a time, I don't know if it makes a difference...

 

[Analine]

When my motor went I only got about 50 psi in the number two and 100 in the four. The one and three were right at 150.

 

[psychlow]

If you didn't have the throttle plate blocked open, you botched the compression test.

If so, redo it and have your friend floor the throttle while he cranks the engine. Also, is your battery fully charged and your starter in good enough condition to crank the engine over quickly?

 

[DSMJim]

If you didn't have the throttle plate blocked open, you botched the compression test.

If so, redo it and have your friend floor the throttle while he cranks the engine. Also, is your battery fully charged and your starter in good enough condition to crank the engine over quickly?

Thats not true, the throttle plate doesn't need to be open. Enough air gets by that you don't have to floor it. Try the test with it open and closed your results will be the same. Then your turning the engine over and it's not running there is very little air movement and the intake manifold has more than enough residual air inside to feed the cylinders as they suck air in and compress afterwards.

Also make sure you crank the engine over until the needle stops but not more than 7-8 times kinda thing.

 

[psychlow]

Thats not true, the throttle plate doesn't need to be open. Enough air gets by that you don't have to floor it.

I agree with you, Jim, that it wouldn't cause readings that low - I have tried it both ways, the difference was about 10-15PSI on each cylinder. That's why I also mentioned the battery/starter, to make sure that we eliminate all possible variables....

If I had compression that in that range and I was sure the comrpession test values were correct, the first thing I'd be checking (after a wet test) is the valve timing to make sure the marks line up. My bet is that the timing has slipped if those numbers are correct.

 

[bastarddsm]

Compression test results should be like a banned question. they are basically worthless, If you really wanna know do a leak down test, that will tell you how much is leaking and from where. But back to the original poster the actual number dosen't mean squat as long as they are all consistent to each other like +or-10%.

have a good day

Kurt Stuart, Phd. Physics