Club 80-90 Forums

Hi, does anyone have any idea why my 1.6 diesel overheats?

The only way to stop it overheating is to have the heater full on, not much fun in the summer!
The radiator does not get hot! I've changed the thermostat (although the old one appears new - fitted at last service?) but that made no difference. Running without a thermostat results in the radiator heating up and no overheating. The fan then operates as normal.

Andy

Have you tried to bleed the coolant system? does it lose coolant? is water pump OK? is there any water getting through the radiator? blockage etc, when it gets hot see if the pipes too and coming away from the rad are hot.
Simon

assuming there was no air lock which in the diesels is not normaly a problem
and without the thermostat everything is normal I would say you are unlucky enough to have 2 duff thermostats. proof in the pudding would be to dangle them in a saucepan of water with a thermometer and check they open at right temperature and they open fully. I think its about 85C start of opening
with a max stroke of 7mm at 105C

Thanks Simon,

There appears to be no leakage of coolant.

I'm not sure about the water pump, it's not making any strange noises etc.

With the thermostat fitted both pipes to the radiator are cold, only the heater matrix gets hot.

I thought it must be the thermosat that was faulty particularly as the radiator heats up when it is removed.

Thanks Stu,

I'll get the pan on the stove...!

Andy

the heater matrix is on a different circuit to the rad and bypasses the thermostat so if thats getting hot then you can assume the pump is working.
besides which they normaly P*** water all over the place and or make horrible noises when they curl their toes up.

where did the thermostat come from?i removed the thermostat on my golf diesel the other month and the genuine one had holes allway round the mounting rim but the non genuine one i refitted didnt when i have previously refilled the cooling system it was just a case of water in and it bleed it's self easy as that with new gsf thermostat i had to remove the top radiator hose and fill it there run it with the hose loose to purge air etc or it just airlocked are real mare might be worth trying a genuine stat for what they cost

Just put both thermostats in a pan of boiling water on the stove and they both work!

Maybe it is air in the system.

I will refit the thermostat later and bleed the system and see if that cures it.

Thanks

Andy

but did you check the temp they start to open and the max gap when water was boiling