Does anyone have any exprience of t25 watercooled transporters blowing the header tank tops off? mine keeps doing it but does nt seem to be getting that hot. but the plastic header tank seems to be distorting from the heat. please help its doing my head in! i have bought a new header tank, new top, bled the system properly, the thermostat is opening, and the temp gauge is not going over halfway! aaaaaaagggggghghh!