Overheating Help!!!

[derekd]

Much Cherished "Old Grey" is getting hot & bothered. (Mark 2 16v 1990)
Car is using water (lots). Engine has never been cooked however!!. New water pump last year, thermostat is OK. No oil in water, or vice versa. Car was running well, but had a flashing temp warning light, despite gauge not moving above normal.
On switching off, it vented down the overflow on the expansion tank, and lost loads of water. On topping up, and seemingly freeing off a suspected airlock in the bottom hose, the engine seemed to run OK, but dumped water again on switching off.
No steam or white smoke from the exhaust, no mayo on the oil filler cap, so I don't think it's the head gasket. Car is only used at weekends, but very reluctant to do so in case I fry the engine. Oil temp running at max 102, cooling fan seems to be OK. Heater is still working normally.
Can anyone offer advice?? Thanks.

[chrismk2]

Mines doing the exact same thing but it split a hose aswell for me creating the air and the loss of water maybe check whilst running let it get up to temp whilst static and have a good look around for leaking?

good luck mate

[Gambit]

as he said. let it sit at idle in your drive and check all coolant pipes for leakage

[dubslug]

i  also had similar problem mine turned out to be thr water bottle cap was f@@ked, might be worth a look??

[Mr Blue]

I have a similar leak problem but it doesnt overheat. I would say do a leak test or get some die and put it in the collant to see where the leak is coming from.

Could this be caused by not having heater bypass valves. preassure then causes leaks in the engine bay?

[moonraker]

i? also had similar problem mine turned out to be the water bottle cap was f@@ked, might be worth a look??

We had the same problem, losing water but no visable leak, after topping up the header tank one morning "madam" left the cap off and lost it, after nearly boiling the engine she purchased a new cap and...........hey presto no more water loss.

Heater still does not work though!!!

[...joe]

i also had similar problem mine turned out to be thr water bottle cap was f@@ked, might be worth a look??

i'd go for this, basiclly the o-ring or rubber ring on the underside can get damaged/mis shaped and as these systems work under pressure any leak will cause it to boil over. and they only cost a couple of quid. this was such a common problem that vw changed the design slightly and all later ones were coloured blue to identify this. so make sure its a blue cap you get and you should have no problems.

[rubjonny]

Replace the plastic coolant flange on the right side of the block as these are a weak spot for leaking on these engines.  You might want to look at the lower flange on the thermostat housing too, as well as the flange on the front of the block.

[The Hoax]

Gtijoe was absolutely right. It was the O ring on the header. Derekd is my brother and we both have valvers. What stumped us was that we actualy tried his header cap on my car and it didn't overheat. We probably should have put my cap on his car and we would have had it sorted earlier.

By the way, old grey is a minter with low 50k miles and is about as nice a Golf as you will find anywhere.

Thanks for all your replies.