My E46 BMW 100k miles auto 325ci recently would start overheating after 20mins of driving. It would instantly cool down if I turned the heater on full. So I took it to a mechanic and the heater pump was faulty which he replaced. Then driving it home, it started overheating again. So I did the heater trick again. I figured he hadn't bled the system properly. Once I got home I let the car sit for a few minutes and then restarted the car. I went to open the bleed screw, but before I could BANG!!! the expansion tank exploded.
What I can't figure out is why is takes 20-30 mins before it starts overheating. And then what caused the tank to explode, not just crack.
Any ideas? Thanks
What exploded from too much pressure odds out of head gasket's blowing on the engine. Sounds like your mechanic is an idiot. Do my test. How to tell if your head gasket is blown. Scotty
Thanks, will do