Clunk From Aux Heater As It Cools Down

[Seatdriver]

Strange one this.

 

Aux heater fires up no problem, but

 

If the car is driven for a short run ie 5min and I turn off the engine there is a perculiar clunk/click sound from the Aux heater area as it cools down, the clunks/click only happens about about 3 times then is quiet other than the humm as it is cooling down which continues for a few minutes.

 

However if the car is driven until its nearly warm and then turned off there is no sound?

 

Any ideas?

Edited February 9, 2010 by Seatdriver

[tim-spam]

If you switch off the engine before it's fully warm, the coolant circulating through the heater is still fairly cool and will cause the heater to cool down more quickly - this could be the cause. I assume of course that the overrun water pump is working.

[Seatdriver]

Good point,

 

Yes engine temp still registering cold when it happens, suppose Aux heater on max and cold water + -3 deg ambient temp = very quick cool down.

 

Will keep an eye on it and see what happens.

Edited February 12, 2010 by Seatdriver