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