What compression?

[nova_saloon]

C20xe engine has low compression in one cyclinder. Come to the conclusion that it is the rings afer a wet test just wondering what PSI./BAR. they should roughly be as theb other three were up at around 197psi and far as i know its standard so may of had the head skimmed, but what should they be at roughly? :thumb:

[let_nova]

around 200 mate.

[Morton]

spot on any where from 160 psi to 200psi depending on wet r dry test etc !!

[nova_saloon]

Well took her for a long drive to warm the engine up got back and whipped the plugs out as fast as i could and whacked the tester in
(cambelt to Gearbox)

Cyclinder 1: 197psi
Cyclinder 2: 197psi
Cyclinder 3: 180psi Wet Test: 210psi
Cyclinder 4: 151psi Wet Test: 189psi
Plus a flat battery so now i know whats causeing the misfire cyclinder 3 wont do to much but 4 is probs causeing the rough idle!
yay Piston ring replacement jobby!
anyone want to lend a hand.?
Live in Upper hale, Farnham Surrey/Hampshire

[Will F]

3 and 4 are lower, but not enough to cause a misfire?

could be h/g though I spose....

[kent14sr]

Sounds like headgasket to me - otherwise a strange coincidence that 3 and 4 are both low!

[John]

gasket failure i'd say.

[nova_saloon]

well no water in the oil anc no oil in the water, i would of thought there would be more of a similarity as soon as the wet test was done the piston 3 went extremely high. to much difference in the compression once the wet test was done.

[MK999]

if the gasket fails between 3 and 4, then there won't be any oil going anywhere.

[nova_saloon]

exactly so the compression wouldnt change in them when doing a wet test

[MK999]

well it would because the seal between the piston rings and bore would be better, if you put a big hole and a little hole in something it doesn't just leak out the big hole.

[nova_saloon]

no im talking about the gasket being busted, thats why you do a wet test to seal the piston better temporarily to see if it ups the pressure and it did so that why i was disagreeing with everyone about it beinb the head gasket

[Rich]

does it smoke at all? just because theres no oil/water mix doesnt mean its not headgasket

[nova_saloon]

Only smokes when i mash it to the floor! which is not very often. But dont see any sign of blowing outside the head gasket, well what i will do is clean all around the head gasket and get a bright light and just splash water about and look for bubbles or something, But to be honest there is a difference in the pressures between 3 and 4 and they would be more simil;ar if the gasket had gone between the both of them and when the wet test was done it went right up. Plus to be honest it needs new bearings and **** so its about that time i ripped the *******o out and rebuilt it. but id rather get a turbo engine and rebuild it but dont have the money at the moment! gay!

Hows things anyways rich you moved all the nova and that to the new place?

[Rich]

Suppose it gives you a reason to freshen up the engine

Not moved it yet, stripped my white gsi of parts. Waiting for the shell to go before i can get the turbo in there. Fed up of relying on people now, was supposed to be gone a week ago! :(

[Will F]

Sounds like it needs a freshen up anyway - but like I said that drop in compression isnt huge and you probably wouldnt see any major symptoms like a misfire etc...

Just make sure you check it all when its apart - like valve seats etc.

[nova_saloon]

Sounds like it needs a freshen up anyway - but like I said that drop in compression isnt huge and you probably wouldnt see any major symptoms like a misfire etc...

Just make sure you check it all when its apart - like valve seats etc.

yeh deffinatly, expensive to go doing this like a reglaze if the rings have shat in the block. but valve seats may be a bit iffy and a gasket set would be in order. what could be causeing the misfire then? driving me nuts. checked the timimng plugs are good lead may need renewing but doubtful. could have a leak somewhere but i dont really know

[Will F]

Do you know which pot is misfiring?

If you know - switch the leads around and see if it 'follows' the misfire

That would rule leads out etc

[nova_saloon]

nope not sure which one is misiring big old guess as to what it is right now, could record it doing it and then show everyone whats happening. just burbles and rough idles and needs a kick in the ****