My lovely 2002 convertible is pumping out all its coolant on every journey. It is over filling the overflow bottle in the inner wing. I suspected the heater core because all the obvious hoses and expansion tank look OK. I short circuited the flow to the heater core with a short pipe from ebay to cut out the heater core, but no improvement. I suspect it may be the small electric motor on the fire wall under the coolant flow control. Does anyone have any experience on this?

 

Try using a coolant pressure tester. If the coolant is overflowing it may be expanding excessively because it is not being held under pressure.

It also could be a the fill tank cap not holding pressure.

And BTW, do not take any more journeys until this is solved...you run a serious risk of major overheating engine damage.

 

+1

Never run with a cooling issue. Overheating is an engine killer on these cars.

The Atmospheric Recovery Bottle in the wing has a large capacity. If it is overfilling, you have very little coolant left circulating the engine.

There has been a recent thread on the Heater Motor Pump. It's in the HOW TO at the top of the threads:

https://www.jaguarforums.com/forum/x...41/#post752880

Graham