compression test

[g40chris]

right i thought i would check the compression with a compression tester to see if rings could be at fault for heavy breathing

i done a compression test with the car stone cold

cylinder 1 = 125psi
cylinder 2 = 125psi
cylinder 3 = 110psi
cylinder 4 = 100psi


so i then warmed the engine up to operating temperature and done the test again

cylinder 1 = 105psi
cylinder 2 = 100psi
cylinder 3 = 100psi
cylinder 4 = 100psi

these seem a bit low to me. the spark plugs had oil on thread and probe.

a few people are telling me they think its rings which if it is then im definately breaking the car as i cant throw anymore money at it. is there any other things that could cause these results or do you guys thnk the results are ok.

the car has 1308cc pistons in it, does anyone know what compression these should run.

also when the car was warming up i had a multimeter linked up to the battery and it started to drop from 14.05 volts to as low as 13.2 volts and the car had dropped to 600rpm and cut out once. also seemed to be hard to turn over after it cut out. could crankcase pressure cause this?

im not sure what to do next?

[Alexiskayak_7]

According to autodata you have to warm up your engine and the stock engine (with 8:1 comp ratio) must have 8bar

[g40chris]

yeah i warmed the engine up

so 8bar is around 112psi i think

mine has a metal head gasket and bigger pistons. im sure i should have higher compression than stock tbh

[Alexiskayak_7]

8 bar is 116psi... Yes, your comression is ok!

[lance]

how many miles have you done since you 1308 it?

[g40chris]

about 1400 miles

[Alexiskayak_7]

mmm... you should make more miles so the engine get rodaged...

[g40chris]

it wasnt breathing this heavy before only started doing it recently, last few weeks.

breather pipe at back of block looks like salad cream. no water in the oil though. could i just have a blockage somewhere.

so my compression is ok then

[Alexiskayak_7]

Chris, does your car makes grey smoke from the exhaust?

[g40chris]

1st time i noticed some the other day but that has been only since i reconnected the boost return so the heavy breathing is going back into the system and through the exhaust or so i assumed. couldnt tell what colour it was to be honest and it seemed to be only under load

[hayesey]

I would say those compression results when at temperature are pretty low, it's less than 7bar.

[lance]

your lookin at 3k miles untill its all settled in though, the compression is rather low, did you build it all up yourself? the rings could be ok just fitted wrong.

[g40chris]

a vw mechanic fitted them for me.