Car overheating at idle then goes back down to normal temp when driving

[adriano10]

my da says its overheating will at idle then goes back down when its been driving , could this be the thermostat or water pump ??

[dougie_504]

Radiator fan probably not working and therefore not putting air through the radiator when temp goes up.

When you drive the speed of the car forces the air through the radiator to cool the engine down.


Turn your car on cold, let it warm up at idle, bonnet open, and look/listen to see if the radiator fans turns on.

[adriano10]

Radiator fan probably not working and therefore not putting air through the radiator when temp goes up.

When you drive the speed of the car forces the air through the radiator to cool the engine down.


Turn your car on cold, let it warm up at idle, bonnet open, and look/listen to see if the radiator fans turns on.

fans power up after it warms up =/

[grifty]

it could be that the thermostat is not fully opening, it could also be a partially blocked radiator, change the thermostat first and see if that works.

[bennjamin]

does the tempreture go down and remain the exact same level ( about halfway as per normal) when driving - and no more / no less ?
Thermo fan isnt working so test it ( pull the fan switch off and short it ( located on the thermostat housing , get a paper clip or audio wire and short the two connectors inside. If its OK the fan should turn on instantly)

[dougie_504]

If the fan is working then like Ben said I'd try thermostat first.

A partially blocked radiator can still perform adequately up to a point - my last one was 40% blocked and still did the job fine. But taking out a radiator, having it cleaned up inside, seals replaced etc isn't as cheap as thermostat...