Coolant under Pressure

[mosket]

I have found myself in a never ending search to find why my 01 D2 coolant system comes under very high pressure when the engine reaches operating temp. I assumed it was the head gaskets so i replaced them. I got everything back together and still had the waterfall sound behind the dashboard. So i re-bled the system several more times, only after the engine sat over night, which helped but didn't solve the problem. I tested for hydrocarbons in the coolant and it was negative. It seems that as soon as the thermostat opens, or is supposed to, to let coolant through the radiator it immediately flows out of the expansion tank, if the cap is off, and if the cap is on it starts to push the coolant down into the hoses. the pressure dissipates when the car sits over night and i do not lose coolant if the cap is on.
I know this is a lot but i am at a loss and could use any advice. thanks so much.

 

[joey]

If you still have the waterfall sound in the dash the system isn't bled.

 

[mosket]

Yeah that is what i figured. I am replacing the radiator next weekend along with the thermostat so I will worry about it more then. In the mean time the rover will do what
Rovers do best and sit in the driveway in pieces

 

[joey]

When bleeding the system it is easier if the front of the rover is a foot or so higher than the rear.