Ok my boss has a1998 548i? (i think...) BMW and his upper radiator hose keeps popping off while hes driving as soon as the car gets warmed up which he says is after about 10 mins at the most. he says the temp gauge runs hot then the hose pops off and throws his coolant everywhere,what would cause this?says he has no heat eithe but hard to tell if the car was only running for 10 mins everytime befoe this happened not enough time for heat IMO