I have a 1985 520i (E28). Car has only covered 68000 miles in it's life and is very clean but keeps overheating. Changed the fan clutch etc, radiator seems to be ok (no cold patches) and it doesn't lose any coolant. Garage says there may be a crack in the head or block but they don' know without taking the engine apart. Is this likely? I keep reading so many different theories on this subject, but can anyone tell me where is the best place to start, don't want to start replacing everything if there a simple answer. Thanks

there are numerous reasons why the car overheats. i'll give you a checklist:
1. low coolant level due to leakage of coolant (pressure test the cooling system)
2. accumulation of rust and scale which prevents normal circulat6ion of coolant (the system should be flushed)
3. collapsed hoses
4. thermostat stuck closed, blocking the coolant circulation (if the drive belt is not slipping and the engine overheats without the radiator becoming warm, the thermostat is probably defective)
5. defective water pump that does not circulate enough coolant
6. a loose or worn drive belt that slips. then it will not turn the water pump fast enough for normal coolant circulation.
7. afterboil, when the engine is turned off after a long drive, the heat build up in the engine may cause the coolant to boil.
8. frozen coolant. the combustion chamber heats the coolant around it first. the frozen coolant cannot circulate, so it boils. freezing of the coolant can crack the head and block, and split the radiator.

goodluck.


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