Compression Test How-To

[tran03]

Great writeup. I was about to go do this at a dealership or a shop but now I think I can do it myself.

Thanks a lot. I'll post results by this weekend.

Tony

[evodan2004]

ok i did the how to which worked great but here are my results.

1. 170 at 7 cranks 180 at 10 cranks
2. 175 at 7 cranks 180 at 10 cranks
3. 175 at 7 cranks 180 at 10 cranks
4. 180 at 7 cranks 185 at 10 cranks

i did not know how many cranks to allow so i did a reading a 5 7 and 10. 5 was the same at 7 basically..

so to the pro's how is my compression looking???



to do a wet test how much oil do we add?? do we do it when the motor is hot as well??


03 evo8
stock blcok
60k miles

[evodan2004]

Originally Posted by evodan2004

ok i did the how to which worked great but here are my results.

1. 170 at 7 cranks 180 at 10 cranks
2. 175 at 7 cranks 180 at 10 cranks
3. 175 at 7 cranks 180 at 10 cranks
4. 180 at 7 cranks 185 at 10 cranks

i did not know how many cranks to allow so i did a reading a 5 7 and 10. 5 was the same at 7 basically..

so to the pro's how is my compression looking???



to do a wet test how much oil do we add?? do we do it when the motor is hot as well??


03 evo8
stock blcok
60k miles

bump

[evodan2004]

Originally Posted by evodan2004

ok i did the how to which worked great but here are my results.

1. 170 at 7 cranks 180 at 10 cranks
2. 175 at 7 cranks 180 at 10 cranks
3. 175 at 7 cranks 180 at 10 cranks
4. 180 at 7 cranks 185 at 10 cranks

i did not know how many cranks to allow so i did a reading a 5 7 and 10. 5 was the same at 7 basically..

so to the pro's how is my compression looking???



to do a wet test how much oil do we add?? do we do it when the motor is hot as well??


03 evo8
stock blcok
60k miles

bump

sorry motor is getting cold. dont know if i should do this hot warm cold.

[evodan2004]

bump

[broddey]

So if I can't keep my engine running for long, what should the compression be when cold?

Mine read 120 on three cylinders and 115 on the fourth. Any ideas as to whether or not this is normal on a cold engine?

[BosanskaTrava]

bump for last two questions!

[aspensvt16]

I got 177 178 177 180 from passenger to driver side. I let the engine crank over for approximatly 3 seconds. Engine coolant temp was 50 degrees. Does is change if the car was not warmed up before the engine was compression tested? Does the amount or time you let your engine crank over increase the psi.

[Inprogress]

Will I need anything else besides this?

http://www.harborfreight.com/cpi/cta...emnumber=95187

In terms of any connectors?

I know I'll need connectors to remove the old spark plugs, but what about connecting the compression tester into the cylinder?

[Redline06]

Bumping from the dead.. lol

Can this method be applied to other cars as well.. ie. the wife's corolla..lol

[Sievers]

Nice. Does anyone know how to find out your compression ratio? I have no idea.

[detroit pistins]

bump

[guapoholic]

As a rule, most engines should have 140 to 160 lbs. (in the Evos case High 170) of cranking compression with no more than 10% difference between any of the cylinders.

-Low compression in one cylinder usually indicates a bad exhaust valve.
-Low compression in two adjacent cylinders typically means you have a bad head gasket.
-Low compression in all cylinders would tell you the rings and cylinders are worn and the engine needs to be overhauled.

[xRoguex]

Just picked up my evo - did a test. Car has unknown mods. with 60k on it - i got 179 across the board on 5 cranks.


Sounds odd?

[kaj]

155/150/155/132

:-(