urgent help please

[Flyntoy]

hey ive got a problem with my car and im thinking its the head gasket but hoping its not,. anyway my car was really low on water the other day, i hadnt checked it got ages so i filled it up. then last night once id parked up and stopped my car i could hear it boiling, the water was fully boiling so I let it cool down and topped it up with hot water, after a while of bleeding the air bulbble out of the radiator there was a fair bit of them at times i topped it up with water.
I then realised the radiator cap was totally f*cked, so i replaced the radiator cap and took the car for a drive, came back turned it off and i could hear some little bubbling now and again very faint and it was only coming from the big pipe between the block and the radiator you can feel it when u squeeze on the pipe. im thinking maybe there was a few small bubble still stuck in there, im gonna try and bleed them out tonight,. does anyone know what could be wrong? i was thinking maybe head gasket but i did pressure test it and it came back ok. or did it just overheat from a faulty radiator cap causing bubbles to form and some are still stuck in the system,.???

any help would be greatly appreciated

[Ae92typeX]

Im sure you have, but have you filled it up and ran it to operating temp and longer while looking for any leaks?. sometimes you can get a pinhole leak in the pipes which only pisses out the water when at full operating temp and the water pressure has built up (as long as the new cap is all good that is).
also check aroung the waterpump, many leak when worn.
Any clouds comming out the exhaust when you drive/rev it?

[Flyntoy]

yeh i did all that,. couldnt find a leak,. checked the waterpump seemed ok. im thinking now that maybe the radiator cap was f*cked and that caused it to overheat. now the thermostat is cooked and is not letting water through thus making that little bubbling noise, as the noise is coming from where the thermostat is