I think My head Gasket went..

[deansbimmer]

My M20 is plagued with inconsistent overheating problems. The water is brown, I've flushed it and it remains brown, but its not an oily feel, and there's no water in the crankcase. Sometimes it overheats, sometimes it doesnt - like if I run the heater...

It heats up because air pockets continue to form in the water jackets and I have to stop and bleed them out of there.

Could this be due to a failing head gasket? It has a new radiator, water pump, and hoses, and the engine seems to run great.

[Garageaholic]

are you using brown coolant.

[deansbimmer]

No. Until I could figure it out, I only replaced the coolant with water when I flushed the system.

[Garageaholic]

ok.

1. I hope you've been using the green coolant, not the orange (it has a degradating chemical to the seals)

2. I don't necessarily think that a "non-oily" feeling coolant means that there is no oil in there.

You probably have air in the system... Sometimes the bleeder valve doesn't always get all the air out. Raise your coolant tank way above the rest of the engine as you fill it. That should help with air out of the system.

[nando]

if you want to get picky, you really should use BMW coolant. the difference was obvious when I did my stroker, between my old block (which has only seen BMW coolant) and the block from my parts car (which only had seen generic green coolant). guess which one was all nasty and corroded inside?

as far as your HG, yeah sounds like it could be blown. maybe getting pressurized from the combusion chamber - not leaking between an oil seal. definitely not good, and even though it can't hurt your bearings, if you are overheating a lot you are going to warp your head and that's much more expensive than a new HG.

but try bleeding your coolant system all the way first, before tearing apart your head.

[deansbimmer]

No, Using Green antifreeze, but none right now until I can figure this out.

Theres no doubt there is air in the system, but I've bled it three times now, and theres no water leaking from the car anywhere, and everytime I bleed it, air hisses out for 15-30 minutes. There's ALOT of air in there coming from somewhere, I have to bleed it every day and its always the same amount of air. Wierd!

Thanks!

[nando]

No, Using Green antifreeze, but none right now until I can figure this out.

Theres no doubt there is air in the system, but I've bled it three times now, and theres no water leaking from the car anywhere, and everytime I bleed it, air hisses out for 15-30 minutes. There's ALOT of air in there coming from somewhere, I have to bleed it every day and its always the same amount of air. Wierd!

Thanks!

yeah, that's why I said your HG is probably blown, and pressurizing the coolant system from the combustion chamber.

you should do a compression test to see if anything is wrong, and a leakdown test if you find one of the cylinders has much lower compression than the others.

[deansbimmer]

Sounds like I'm doing a headgasket this weekend! Thanks for confirming my suspicions. I'll do a compression test, but I think this seals the deal. Thanks guys!