had a play today new gasket on thermotst housing lock tight on bolts checked all pipes where tight went for a drive pulled up wiv car running cap of no pressure what so ever but i turned the engine of wiv cap still off and wait around 2-3 mins then bubbles start in top hose and lasts for around 5mins then settles been for a few journeys and same every time cant b headgasket else the pressure would b there all the time surly
any ideas