dparrish

Hey guys, I did a compression test on my Evo 8 MR on the weekend. I haven't had it for very long and haven't done any real mods. It's worrying me a little.
The cylinder closest to the cam gears read 131 psi and the rest read 160. My mate showing me how to do it said it's fine don't worry about it. But I don't believe him.

Is that normal or terrible or somewhere in between? What needs to be done if it is bad?

pinoy6969

iTrader: (1)

a good one is suppose to be atleast 10psi away from each other..try putting a table spoon of oil on the hole that has a low compression...then check if goes higher than before

dparrish

OK I'll give that a go tonight. My compression tester screws into the spark plug thread to apparently make a good seal but I'll give that a go. I also tested each cylinder 3 times to make sure.

pinoy6969

iTrader: (1)

yea, i think if the compression goes up it might be a worn or damaged piston ring
and/or cylinder inner surface, If the compression doesn't go up after adding the oil it can be a burnt or defective valve seat, or pressure is leaking from the gasket.

jrlewis0550

iTrader: (4)

I did mine and it was 190 across the board, and i have also seen them around 170. All data says like between 138 and 168, but there shouldn't be more than a 10% difference from lowest and highest. So your #1 piston is low how are you doing the test and is the tester good.