tried stop leak,

flushed system

new lid on coolant bottle

new thermostat

Temp ok

etc, etc.

car loosing coolant with lots of pressure in exp tank - so i cannot refil with coolant as it tries to shower me in hot liquid!

seems to suck coolant out of tank when you welly it for a few miles.

not a stable level of coolant.

usual messages 'stop engine etc'

any clues out there??