Pressure Problem

[Banjo]

Ive been geting problems with my radiatior cap, when i realise it when the cars idling the temps fine but once its tightened the pressure of the water starts boiling and seeping out the cap, and the temp goes right up after only a few mins...

Has anyone had this problem or think off something it may be?

Thanks..

[Sketchy]

Ive been geting problems with my radiatior cap, when i realise it when the cars idling the temps fine but once its tightened the pressure of the water starts boiling and seeping out the cap, and the temp goes right up after only a few mins...

Has anyone had this problem or think off something it may be?

Thanks..

Pressuising of the Water system is normally a sure sign of Head Gasket failure, get a hydrocarbon test done on the water that'll tell for sure if you've got combustion gasses entering the system.