I have a ongoing problem with water pressure, one day all seems good another after 2mins of running water pressure so high it leaking out of the header tank pipe's, have double checked no air lock's, filled system through turbo pipe, heater gets hot etc, i am stumped now to why it doing it, please help.

 

Thermostat? and coolant leaking out of header tank pipes?how did you bleed your system?

 

Can you feel any cold areas in the system?