Help please?? lumpy idle and full expansion bottle when hot

[allante666]

Car has been fine and in fact runs fine while driving. just recently however when i stop after a run, it idles just like a normal car would if the choke was left on (mines a twin turbo) i.e. really lumpy? you can see the car rocking. also when this happens i notice the expansion bottle is full up allthough this gets sucked back in as the engine cools (don tknow if this is normal or not). idles ok when cold. no CEL or anything, temp gauge as normal, any ideas guys?

[Huffer]

Maybe a misfire? or a worn engine mount? How is your oil pressure?

[allante666]

Dont know what my oil pressure is but i have no reason to think it is low, no lights or rattles etc. only started the other day, as soon as you drive off its fine. also when its doing it there seems to be excessive exhaust fumes, not rich fumes or black or anything, just ordinary fumes but seems to be a lot. or of course it might have just been the cold weather made itlook more.

[allante666]

Bubbles in the expansion bottle as well, not looking good is it!

[Sarra]

Uh oh, headgasket... Is the fluid milky, dark, or anything but green/the original color of your coolant?

[allante666]

Its a dark colour but then again it always has been! no froth or scum and the oil is still clean so I think i'll stop running it before it gets any worse. Just out of curiosity has anyone tried that 'steel seal' additive thats supposed to cure HG leaks? (dont fancy it myself but just wondered?)

[allante666]

If its ok when its cold and only does it when its hot, does that still suggest head gasket or is it more likely cracked head?