General Coolant bleed valve

[blu73]

compression tester is cheap, buy one and check compression first - its a damn site easier than taking the belts off!!!

having done a waterpump, its not hard as such but fiddly and access is rubbish (like everything on a GT) - its been a while so can't really remember the exact steps in order but is all pretty obvious when its in front of you.

 

[bellini006]

Does anyone know what the compression should be? Thx

 

[Eklipze3k]

Off the top of my head no, but what you're looking for is all 4 cylinders to be around the same, if one is substantially lower then chances are your head gasket has gone.

 

[blu73]

:yeahthat:
but a really crude calculation though.. Compression ratio on a GT is quite low, 7.8:1...
atmospheric pressure is 14.7
thus compression should be about (7.8 x 14.7)/1
which comes to 114.66psi

But as said, what you are really looking for is a nice even set of readings more than anything else.

do a dry and wet test, i.e. do test and then do it again with a teaspoon-ish of engine oil dropped down each cylinder before test.
Also best to do it a few times and take an average. And remember all plugs out and throttle wide open for test

 

[flisko]

:yeahthat:
but a really crude calculation though.. Compression ratio on a GT is quite low, 7.8:1...
atmospheric pressure is 14.7
thus compression should be about (7.8 x 14.7)/1
which comes to 114.66psi

But as said, what you are really looking for is a nice even set of readings more than anything else.

do a dry and wet test, i.e. do test and then do it again with a teaspoon-ish of engine oil dropped down each cylinder before test.
Also best to do it a few times and take an average. And remember all plugs out and throttle wide open for test

i always wanted to do a compression test just for fun, but i was wondering if it puts more strain to the engine than normal running-cranking?

 

[Eklipze3k]

No

 

[bellini006]

Done a compression test on my car last night. Starting from cambelt side, piston1; 165psi
Piston2; 170psi
Piston3; 150psi
Piston4; 148psi ish
Wot do u think? Done it 4 times on each cylinder and every time around the same.

 

[blu73]

there is more of a spread than you would want, could have gone between cyl 3 & 4 looking at the numbers there. Symptoms are consistent with blown HG as well so i think that might be your problem - did you do a wet test as well? Were the readings higher or the same when doing a wet test??

If you are going to do the HG, while its apart you may as well do the water pump at the same time, and new belts and tensioners - and just check the condition of everything else as you go.

I would advise against a cheap head gasket, you could get one of the cheap kits and use all the other gaskets but i would get either a genuine HG from fiat or a payen or spesso head gasket.