overheating...confussed

[graeme]

ryte i serviced my car today, new thermostat and that was included...but i'm having a problem with overheating, the gauge was fine with no problems i ran it up and got it hot after it had all been done and it was spot on, fan kicked in and everything, then i took it out tonight and the gauge went mad and went straight to the top. could this be the water pump??? i've just had the headgasket done, changed the fan swith, new coolant and thermostat....any ideas please????

[Boumsong]

I'd get the water pump checked if I where you. I had a similar issue, the needle went mental and showed full temperature..Ended up cooking the head and ruining the engine.

[graeme]

the thing i dont understand is when i was filling the expansion tank with coolant the water was circulating perfectly???? so surely it cant be the water pump? or can it???

[Boumsong]

Easy way to test it pull the filler pipe to the tank off whilst it's running, obviously keeping good fluid levels when doing this. If it's no the water pump I'd check all the wiring associated with the new thermostat, it could be a bad earth somewhere.

[markh]

Very possible that you have an air lock in the cooling system mate. When you refill the coolant after draining, you need to make sure the heater is set to hot, to avoid any air locks. You can also remove one of the temperature sensors from the flange in the cylinder head, when filling the system, as this is one of the highest points in the cooling system, and any air trapped will be forced out.

[mark1gls]

Try taking of the top hose of the radiator at the rad end (the one that goes straight into the head) and fill that with water/antifreeze till it starts to come back out of the hose, as it sound like an air lock as markh said make sure the heater is on hot. Also check to see if the heater is blowing out hot air once the car is running.