Mt 2 cents...my friend had the same thing with a 3.0 he bought not running. It was at the dealer 100 times for over heating and they never changed the water pump.

If it where me I would change the water pump and flush the coolant. I would send the radiator out to a shop and have it flushed and check for leaks. If your lucky the impeller fins are worn and that all it is. Yes the thermostat and coolant tank, change them too. These parts will have to be changed anyway at some point even if the head is not leaking.

My friend had to replace the head gasket because it was overheated and driven to far. The head was re-planed by a machine shop.. a must. He ran into a problem with the threads stripping out for the head bolts. The block when overheated does something to weaken the threads. He had to install new steel thread adapters made by BMW just for that, make sure you research and replace those too if it is the head.

From what you're describing the car was overhead and continued driving until the head gasket went. The head gasket repair was either done right or wrong? If the water pump was never changed...you should be able to see that...than maybe they never addressed the overheat problem. Just from what your describing I'll bet the water pump is fine and radiator and thermostat...if it were me I would change that anyway. I'll bet the heat gasket repair is not right...the head is probably warped and some bolts are striped. They probably wouldn't have abandoned a car with just a bad water pump. Even if it's a head, if you bought the car right it's still worth doing. Research those head bolt threads sold by BMW..I'll try and find out more from my friend. If you PM me I'll give you his number...he just went through all that.

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