ok..i did a compression test today.and i had 150 all the way across...i see alot of you guys have over 200 on yours...why is mine only 150? is this bad?? does this make my car slower????




'95 Eclipse RS
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I think it is supposed to be atleast 170. Right? You might need a rebuild. There are a few things you can do I think b4 you make the big decision, but I am unsure to what those are, if anything can be done besides the rebuild. One may be swapping the head gasket. Not sure tho. Someone with experience could tell you more than me.

I've always been told that as long as all pistons register the same compression on the same tool.. then you are good to go.
but again.. that's just what I was told.

try it again with another compressor. that one might be bad and giving you the same compression each time. then come back to us and tell us what happened.


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I find 150 a little low as well. True you do want the same numbers over all 4 cylinders, but you don't want really low numbers either. How many miles you got on the car?



Eric Madden

I think it's much more important that you have numbers close together than have high numbers across the board. The only reason is that the compression testers are known to be off. So the readings maybe be inaccurate to some sense (but the reading is measured the same way across all the cylinders). But if you get one reading that is way off from the rest ie 190 190 180 150 ... that is bad. It means that the particular cylinder may have something wrong with it (bad rings, bent rod, head gasket, etc). If you get numbers less than 100 then I would be more worried but don't worry about the 150. If you are still really concerned run the test again. Make sure to do it properlly (I believe Corbin has a how to on his website ... link anyone?). You may also try a different compression tester like someone else suggested.

Did you do it at operating temperature? The numbers will be lower with the motor cold.

hey thanks alot for the help guys... the car was cold and the compression tester is old...so .. i think im just gonna be happy that they are all close until i can get one of those stroker kits :) BTW..my car has amost 109,000 miles on it..


'95 Eclipse RS
INTERIOR
-Sony CDXM 750
-2 JL Audio 12w0 subs
-Premiere Amp
-CompuStar 2WAS Alarm with Remote Start and Pager
EXTERIOR
-Enkei 15" wheels (came with the car)
PERFORMANCE
-K&N Filter

You are ok as long as the numbers are straight across. A lower number can also mean that the engine is taking some wear, but it is normal and nothing is really broken.

Also before you say *rebuild* do a leak down test to find out exactly why the compression is low. Could be headgasket, valves, rings, piston wear. But as long as there consistent that's a +. Good Luck

Derek