coolant woes

[barnpot]

I have a coolant problem i can't seem to get to the bottom of.

I think i have a leak as after a few weeks the heater stops delivering hot air. I had the system pressure tested and apparently it's fine. Also i notice that the level of water in the expansion tank does not go down. And also remains under pressure. I come back to the car after a week of not driving it and there is still pressure in the cooling system - i get air escaping when i undo the cap of the expansion tank, or when i loosen the clip holding the coolant pipe that is connected to the swirl pot.

Could be an air lock but had system flushed at TVR garage.

Maybe a faulty expansion tank cap?

Any clues?

thanks,

david

[jimed]

I had something similar some time ago, the header tank didn't go down. This was caused by a failure in the hose from the swirl pot to the header, effectively a small flap of the hose delaminated on the inside of the hose which almost made a one way valve which prevented the necessary suck back thus making the header stay full. Solution is to replace the hose (easy to do) and then reblead the system.
Let us know how you go on.
Jim