how do i find out whats causing my bmw 520 year 94 to overheat

nick, December 2008

possible head gasket? my friend has a pajero and he had a few problems. we had to change the radiator as it was leaking. once changed we refilled the system with coolant and road tested the vehicle. after a few minutes the temp gauge went sky high into the red. so we presumed that there wasn't enough water in, as we removed the filler cap the coolant blew up into the air!!. this happened several times over the space of a few days. we eliminated the fact that there was any air in the system as we filled the coolant while the engine was running and had the heating on full. we even changed the temperature switch on the radiator. after much headbanging it was the cylinder head gasket at fault. may not be your answer to your problem but please consider as you never know!

shaffick, December 2008

You're going to have to work through and eliminate the possible causes.
1. Is your coolant level correct?
2. Is the drive belt to your water pump slipping?
3. Is the radiator matrix blocked?
4. Is the thermostat stuck closed?
5. Is there a collapsed hose in the system?
If the fault has got worse gradually it may be the cooling system needs flushing through to remove sediment that can restrict the flow. If it has come on suddenly it is more likely to be the thermostat. Other possibilities are to do with the engine producing more heat than usual, but you would have other symptoms if that were the case. If you can take the thermostat out and flush the system through and then fit a new thermostat that deals with a number of potential causes in one go. Good luck

Richard, December 2008