possible head gasket problem on C20XE

[Mitch2]

I think i might have a possible head gasket problem. I have noticed what looks like oil in the header tank in my corsa. It looks like thin lines of oil floating on the top of the water. I have flushed the cooling system but it is still there. I have done a compression test and all four cylinders are fine. I have checked the oil cap and the dipstick and no water has got in to the oil. Wondering if i could have a porous head or a damaged head gasket that has not yet affected the compression. Does anybody have any ideas?

[nova2l16v]

change it just to be sure. i had a cav with a 2l 16v gt oil in the water but nt in the oil an it split the head lol nt good. just change it to be sure.

[Mitch2]

should i get the head skimmed and pressure tested at the same time?

[nova2l16v]

i would recommend tht u do. depends hw much u love ure engine lol.

[Scoobler]

If you have a haynes manual, check your head with a straight edge and a feela gauge set - it tells you in the haynes how to check this - saves on possibly un-needed skimming. Is threre lots of oil in the water, or just a little bit?

[Mitch2]

there is hardly any oil at all. There is probably only a drop or two of oil in the header tank. It might have dropped in, but it could be something worse.

[nova2l16v]

all up to you then mate better safe then sorry i say. least you will no that it has a new head gasket and you dont have to worry about it...

[AussieKid]

u always face a head when its been taken off
even if its just been put on, torqued up and not even driven
the metal in a headgasket is enough to leave a mark in the alloy leaving it not 100% true when u take it off..
even if they only take off 2-3 thou which is usually what they do

[VauxMad_Kris]

sounds to me the head has gone pourous.

[Teknobry]

Whilst the head is off do the porous mod. A lad on here does it for £40. Its piece of mind even if it hasn't gone (sounds like it has though)

[nova2l16v]

what is the porous mod?

[Teknobry]

Sleaves the oil/water gallery wall. If its already cracked then it seals it and prevents oil getting into the coolant.

[Scoobler]

Take a look on www.orsas.com/CarStuff/cav shows what the problem is, and what you are aiming for to fix it

The lad that does the fox for you is Chris R

[nova2l16v]

ahhh i see now! so thts were the gm boys went wrong but the cosworth ppl did rite.

[Scoobler]

I used to have a diagram, can't find it any more, but it showed the differences between the GM casting and the coscast casting. Some say its also a different alloy but couldn't say for sure. As far as I am aware, the 'roof' of the water gallery should have been a uniform thinckness, or at least symetrical to the water gallery to the left (B's in the picture on the causes page) - as you can see from the picture on that site, its not, and at its thinest it can crack. Its a reasonably easy fix though!