Hi all, I've been searching around the internet but haven't found any answers. Basically, my coolant level keeps dropping when/after running the engine (comes up on dash as low). But as soon as i open the cap and the tank de-pressurises the tank fills up again to the maximum mark. It's not actually losing anywhere the coolant as such, it's just not releasing the pressure. If I leave the engine to go cold it still doesn't come back up to max until I open the filler cap on the header tank! Does anybody know what is going on? I've checked the cap but can't see a pressure release hole or anything on it! Thanks in advance!