BMW 318

1998 BMW 318 Engine   

I recently had a heater hose blow, and replaced, when the mechanic fixed it he also replaced the radiator(said there was internal leak) and a vacuum line that needed to be replaced. The car overheated days later and I took it back to bleed the air it has heated up 2 more times now in which I followed the mechanic's instructions and haynes manual to bleed it and it was fine afterward. I am worried though how it keeps getting air in the system and I am not sure if its related but the heater doesn't get very hot anymore. The mechanic can't check it out for awhile and I have to go to him since he is doing me a favor and letting me pay him in payments but I just would like an idea of what it could be. He thinks it might be the head (which is more than what I paid for the car) but he did a compression check on it when it first blew the hose and it was fine.. any imput would be very very appreciated.

A compression test won't always catch a head gasket problem (especially a problem that is just starting).

I am curious if the air was ever completely bled from the system. Has heat returned now?

Any white smoke from the exhaust and/or coolant loss?

First thank you for answering me!! No, no white smoke, yet anyways. The heat does work it just takes about three times as long to get 1/2 as warm as it used to. As far as the air being bled out, the first time it heated back up it was about three days after the replacements were made and his mechanic bled it. Then it was oh about 4 days later it heated up and was bled again then it took about another 4 days before it heated up again. In between times it runs just fine at normal tempurature even when I took it up a big mountain for what totaled as about a 3 hour drive. So its very odd.

I forgot about the coolant... It does loose some coolant once it is overheated,the mechanic said it is probably releasing pressure. but the rest of the time there has been no coolant leaking.

Okay, in this case what is called a block test should be performed. This is a chemical test that detects combustion gases. The presence, or lack thereof, will determine if combustion gases are entering the coolant. This test doesn't cost a fortune and should of already been performed. It sounds like you may be making payments on parts your car didn't need, tough call.