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Re: Cluch Fan question (long) (archive)
[ Follow Ups ] [ 7-series (E23) Message Board ] [ Msg. Board FAQ ]
Posted by Ralph on July 28, 2001 at 18:49:17:

In Reply to: Cluch Fan question (long) posted by Daniel Davis on July 28, 2001 at 17:28:50:


Ok, over the last couple months i have ask question regarding my overheating problem on my 733i. I have replaced the Aux. Fan sqitchs witch help it form not going all the way to the red zone but it still gets very close to it. But now my question is, i found out that two years ago this car had its radiator replaced(band new, and it still does look new), but it look like its not as thick(or its has less width). Could the cause of my over heating problem be that my CLUCH FAN is not close enought to the radiator. Thus causing it not to pull enought air threw it? I do know that the cluch fan works, be cause on hot days, i can opent he hood, and put my hand at the back of then engine and fell lots of air being push.

Any help or comments on this would be great!

Thanks,
Daniel
83, 733i


I have a high-mileage 735i. The rad is 16 yrs old, and the fan clutch hasn't been replaced, aux fan is off-balance making hell of a racket when turned on. Unfortunately, it appears they built these cars with a fairly small rad for the workhorse 6 cylinder. I had overheating problems previously until I took out my thermostat. The temp. gauge will still climb in stop trafficit to about 2/3 after warm-up, but as soon as I get back up to speed 30 mph or more, it comes down immediately to 1/2 or below that (in hot weather). What temp. are you getting at highway speed or 30 mph or more? I did just the opposite to what you did - I removed the #3 fuse to prevent the aux fan from engaging due to the noise it makes - too cheep to put a new one in !! (I don't have air running anyways) If you don't use your car during the winter months, I would suggest taking out the thermostat altogether - you will burn a bit more fuel on warm-up, but then at cruising speed 30mph or more, the temp. will stay between 1/3 to just under 1/2 (at 100 mph). I would also have a close look at your hoses - if you are loosing coolant, even just a drop now and then, the resultant loss of pressure (and coolant) will prevent your thermostat from opening when it should, thereby restricting flow. The short 90 deg. angle hose and the smaller 1 inch hose which travels down alongside the intake manifold to the T joint were the two hoses I found had small leaks and needed replacing. Note: (it appears these cars were designed to overheat) the factory manual tells you that "when" the car overheats in stop traffic, put the car in neutral and rev the engine up to 1500 rpm's to bring up the flow (water and air).
I've got 370,000 km's on my 735i - I haven't noticed a huge difference in fuel consumption since removing the thermostat (car weighs in at over 4000 lbs. anyways) - with the increased flow, car runs cooler, including its occupants !
Let us know what you do. Good luck.
-R.

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