Overheating BMW 540I

[Jason407 0]

Hi all.

New member here, new to the World of BMW, and having problems with a 1999 540I, I'll elaborate in the maintanence forum. haven't had it long and it is over heating, have replaced the water pump, thermostat, radiator and had a cylinder leakage test done, no leaks found, pressure tested the cooling system, after an hour of holding pressure we gave up on that.

Done a TK test on it, there was no exhaust gasses detected.

If driving fast it stays cool, once we slow down, it over heats.

Can anyone think of any other reason for the overheating?

[Guest Si Vis Pacem]

Hi all.

New member here, new to the World of BMW, and having problems with a 1999 540I, I'll elaborate in the maintanence forum. haven't had it long and it is over heating, have replaced the water pump, thermostat, radiator and had a cylinder leakage test done, no leaks found, pressure tested the cooling system, after an hour of holding pressure we gave up on that.

Done a TK test on it, there was no exhaust gasses detected.

If driving fast it stays cool, once we slow down, it over heats.

Can anyone think of any other reason for the overheating?

Does that model have a viscous-drive fan? If so, check it by giving it a spin with your hand, if the fan spins freely then it needs replacing.

[_Matt_ 42]

sounds like a problem with the fan yea.

[Jason407 0]

Hi all, thanks for the fast reply, my dand and I are trying to fix this thing, we it does have a viscous fan, it was spinning but we have replaced it anyway, still over heats, I can't think of anything else except for pulling the heads but would like to avoid that if possible.

[_Matt_ 42]

so it spins by itself? when the car sits idle and is hot does the fan boot up?

[Jason407 0]

so it spins by itself? when the car sits idle and is hot does the fan boot up?

Yes the fan spins slightly stiff, when the car is started the fan can be heard spinning hard and then slows down.

It does spin when the car is at idel and hot

[*Glenn* 854]

Does that model have a viscous-drive fan? If so, check it by giving it a spin with your hand, if the fan spins freely then it needs replacing.

Wrong

[*Glenn* 854]

Hi all, thanks for the fast reply, my dand and I are trying to fix this thing, we it does have a viscous fan, it was spinning but we have replaced it anyway, still over heats, I can't think of anything else except for pulling the heads but would like to avoid that if possible.

Don't do that. Never , never pull things apart without diagnosing the exact fault first. Once dissabled you have no way of doing any further diagnostic work. You must diagnose the fault first. Do you have access to someone with a scanner, a BMW cooling system pressure tester ? Also check that the auxillary water pump for the heater system works and the electric cooling fan in front of the condsenser works at full speed when the engine gets too hot. Does the car loose water ? and have you checked that it is actualy overheating and not just a guage error. Has it been checked with an infra red thermometor ?

Would also help if we knew where you were from. I can help after the 5th

Edited December 24, 2010 by *Glenn*

[kiwi535 538]

the system may also need to be bled of air which can impede the flow of water

[*Glenn* 854]

the system may also need to be bled of air which can impede the flow of water

Sorry.. not correct unless the car has a problem. 1999 540 will self bleed if the auxillary water pump & duo valve system is working correctly and if it is done properly.

[kiwi535 538]

Sorry.. not correct unless the car has a problem. 1999 540 will self bleed if the auxillary water pump & duo valve system is working correctly and if it is done properly.

thats why i said may

[Guest Si Vis Pacem]

Wrong

The master has spoken! Wrong why?

Cheers

[polley 916]

The master has spoken! Wrong why?

Cheers

Because that is not how a viscous fan works.

[Guest Si Vis Pacem]

Because that is not how a viscous fan works.

Another one!

For goodness sake you forum members, please qualify your statements/replies. This forum seems to be trending away from the informative, not useful at all.