Head gasket failure !!

[T2Andy]

Having spoke to a few members I've come to the conclution that my h/g maybe failing can't seem to bleed the cooling system lots of bubbling in the pipes and the cars is very lumpy at low revs but gets better when hot ,can be very jerky on part throttle ,the header tank isn't getting warm or hot but when I undo the cap when the engine is hot is starts spitting and bubbling like a percolator through the overflow pipe ,was thinking the thermostat as the bottom of the rad is cold too ,you can hear an feel the water boiling in the top water pipe when you stop .

[BrianSmith_S2]

Having spoke to a few members I've come to the conclution that my h/g maybe failing can't seem to bleed the cooling system lots of bubbling in the pipes and the cars is very lumpy at low revs but gets better when hot ,can be very jerky on part throttle ,the header tank isn't getting warm or hot but when I undo the cap when the engine is hot is starts spitting and bubbling like a percolator through the overflow pipe ,was thinking the thermostat as the bottom of the rad is cold too ,you can hear an feel the water boiling in the top water pipe when you stop .

As far as i know its normal for the lower part of the rad to be cold when the top gets warm on initial warm up because the water pump draws water through from the lower hose and spits it back hot to the top hose.

[chezz]

Possibly a terminal lack of circulation...thermostat sounds like it could be jammed shut.
Usually, this causes the hot fluids to retreat back up to the header.
So you may have head gasket damage already... dont overlook the thermostat, as it is the most likely cause.

[T2Andy]

Thermostat is the cheapest option will check first

[chezz]

Lets just hope that no serious damage has occurred.
I purchased a Porsche 944 once and the moron that owned it had installed the thermostat incorrectly...furnace like temperatures, I could not get within 3 feet of the engine bay!

[T2Andy]

Done a block test tonight and gas is present in the coolant confirming the hg is leaking but doesn't seem major at the moment

[chezz]

The probability is, that the head has been cooking in its own juices - like your mothers Sunday roast Beef joint.
If the gasket has failed, then something must have caused this problem and you need to establish/investigate the cause...

[T2Andy]

The rad broke at the top hose and dumped most of the water about 1/4 mile from home and I limped it home so prob cooked the head :bonk

[4WheelDrifter]

Sorry to see that Andy.

Have you got a metal headgasket, or has a peper one made its way into your engine?

When the headgaskets fail the combustion chambers tend to break through to the coolant channels at the back of the engine, usually starting at cylinder 5.

If you carefully make sure there is no pressure in the header tank, then start the engine, run it for 5-10 seconds and stop. Check again to see if the header tank is pressurised.
If there is pressure in the tank, it can force coolant into the combustion chambers after the engine is stopped. This can cause rough start-up when cold, and at worst a hydrolock.

[T2Andy]

I'm sure the gasket was changed when qst did the head work about 20k ago ,maybe i overheated it with the water loss,the header tank is not getting hot at all but when the cap is removed the water rises up and then goes down again ,temp is mainly at 87/90'.

[Quattro Dan.]

Done a block test tonight and gas is present in the coolant confirming the hg is leaking but doesn't seem major at the moment

Was the first time i have used my block tester, worked very well. Bad news but it was reasuring to confirm the problem before striping the engine.

Cheers,

Dan.

[Sonic]

Was the first time i have used my block tester, worked very well. Bad news but it was reasuring to confirm the problem before striping the engine.

Cheers,

Dan.

I've got a leaky hg also, in the same boat

[Ross]

Good excuse for a bit more headwork?

[Big Lee M]

Sonic are you sure it's your head gasket and not the head it's self? I thought mine head gasket had gone untill it was taken off and the gasket was in very good nick as it had only been on two years, turned out that the head was cracked.

[SteveH]

I've had a cracked head on my S2. Some also suffer from porosity in the alloy which doesn't help either. I had my head sent off and ultrasealed for about £125 - http://www.ultraseal.co.uk/