My 635 got hot yesterday from a bad thermostat. I have had the car four days and this worries me. I have this thing about warping/cracking heads. Anybody out there have any recomendations for upgrading my radiator/fan set up? I wouldn't even mind upgrading my water pump.

The stock cooling system is adequate for normal driving. But if you leave it idling with the A/C on for to long there is a possibility that the car will overheat with a properly working cooling system.

I would make sure all components are working properly first and well maintained.

Proper fluid levels, leaks, etc. The first thing that should be on your list is a worn out water pump since it sounds like you already changed the thermostat. Next would be a clogged radiator.

Hope this helps because I've seen a few heads destroyed due to overheating....

Thanks for the reply.
Well, considering my drive into work this morning the car never got over half on the guage I think the t-stat covers it.
I did talk to a mechanic by my home and he offered two other places to look for problems. He states that if an e-24 sits for a period of time (mine sat for a year) the hose running from the radiator to the air diverter can cause problems. What happens is the fluid gels and blocks the hose. This can cause an air bubble that can wreak havoc with the t-stat and/or coolant sensors as air is a bad conductor of heat.
At least that is the way I understood it from the mechanic. Who I have a feeling is going to be my new best friend here in the near future.

Now, how about that bleed screw on the t-stat cover?

Is the car still over-heating or did you change the thermostat and it is fixed?

Is the engine fan clutch OK?
Is the shroud flat against the radiator and not warped on the sides?
Is the electric Aux fan working?
(Turn the key on, but don't start the car and then push the A/C button, you should hear the Aux fan come on low. There is a high speed also.)

There is no after-market manual for the six, but the 6-series shares it's engine, drivetrain, suspension and many systems with the 5-series, So a very good substitute is the Bentley BMW 5-series '82 to '88 Manual ($37 from Amazon). Highly recomended.

For wiring diagrams (ETM's), download a free PDF file of the ETM for your year car here:

http://wedophones.com/BMWManualsLead.htm

For Parts diagrams, use:

http://www.realoem.com/bmw/select.do?vin=&kind=P&series=E24&arch=1


Welcome To The Madness!!?

....... the hose running from the radiator to the air diverter

What is an "air diverter"?



Now, how about that bleed screw on the t-stat cover?You need to bleed the system after putting the T-stat in. You are suspost to slooowly fill the system with it open until is comes out of the little slot just below it. Then close it and start the car, turn the heater on and bring it up to temp and then bleed it again untill bubbles stop coming out.

+1 on the previous post concerning the fan clutch. Mine had overheating problems years ago when I first aquired it. Changed the thermostat and it did run at times without overheating, but, other days it went hot in a hurry. Changed the fan clutch and now I can idle in traffic forever and no problems. A fan clutch is a cheap fix and you can do it yourself relatively easily. Its snug when working around the fan and radiator but it can be done.

Well, from what I can tell, the fan clutch is working fine. I watched as the motor heated up and saw the fan speed up. The aux. electric fan is a different story. I think the sensor is bad in the radiator. When I turn on the A/C the fan comes on. But, when the engine is hot it does not. Not until I just it that is. With the t-stat out it isn't getting as hot but it is still getting up there while in stop and go traffic.
Thanks for the info on bleeding the system. Never owned a car that I needed to do that to.

[quote=CW6er;10281053]What is an "air diverter"?quote]
I don't know, just repeating what I was told.

Well, from what I can tell, the fan clutch is working fine. I watched as the motor heated up and saw the fan speed up. The aux. electric fan is a different story. I think the sensor is bad in the radiator. When I turn on the A/C the fan comes on. But, when the engine is hot it does not. Not until I just it that is. With the t-stat out it isn't getting as hot but it is still getting up there while in stop and go traffic.
Thanks for the info on bleeding the system. Never owned a car that I needed to do that to.

Here is the setup for the Aux fan, nice and simple huh? Check the fuses and relays first, then jumper the temp switches to test them. Since the A/C turns on the fan, you know that K1 is good so swap K8 for K1 to test it. Your year is a little different from the diagram below, the normal speed switch is on fuse 18 and connects to terminal 86 of K1 relay instead of directly to the resistor - have you downloaded your ETM yet?

http://www.stormpages.com/countchocula1/bmw/bmwetm155.jpg

Thanks for all your replies. They were very helpful.
When it came down to it......the stupid fan belt was missing "notches" so the cooling was intermittant. It would spin then it would line up just right and stop spinning. My dumb ass saw the fan belt and never thought to check to see what kind of shape it was in.

by air diverter im guessing it would be the plastic around the fan covering the rad , its supposed to direct the pull of the fan to the whole rad but sometimes it warps on the sides , makes a higher ideling temp