Fan Not Running

white lancer · #1 08-25-2013, 04:57 PM

BMW X5 3.0 2004 M54

I drove 200 miles in my X5 yesterday and the temp gauge was fine all the way on 90 degrees but when I arrived I noticed steam coming from the engine bay. I popped the hood and found a pin prick sized hole in the expansion tank and there was a fine jet of water / steam squirting out. I could hear the water in the system boiling inside. When it cooled down I replaced 3 litres of water and put in 250 ml of radweld to try and get me Back home today. It seemed as though the radiator fan was not working when the engine was so hot. Strange though that the car does not overheat when being driven? Maybe the airflow over the radiator when motoring along is sufficient to keep everything cool but as the fan is not cutting in it gets too hot when stopped. When is the fan supposed to kick in? what controls the fan to start / stop. regards. Tony.

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upallnight · #2 08-25-2013, 06:43 PM

On my X I have two fans, a fan behind the radiator with a clutch and an electrical fan on the front that comes on when the AC is running.

ylwjacket · #3 08-25-2013, 08:05 PM

My electric fan went out, right after my expansion tank blew up. I looked into at the time, but can't remember if there was a direct link or not.

Anyways, the car was OK while moving without the electric fan, but overheated very fast when idling.

You need to check and see if it's working, and if not, replace it quickly.

I did it myself, using instructions on here, and bought an aftermarket fan from eBay for half what a BMW branded one was going to be. I believe it's made by Behr, and the one I bought from eBay was made by the OEM manufacturer for eBay.

white lancer · #4 08-26-2013, 07:33 AM

I have two fans on the X5. One behind the radiator which does not work and the electric fan in front of the air conditioning condenser which does not work. I think the electric fan is just to do with the air conditioning and cools the condenser. It is the fan behind the radiator which I want to get running first as this will keep the engine cool when idling. What makes the radiator fan run? is it to do with the temperature of the radiator coolant?

upallnight · #5 08-26-2013, 07:41 AM

You need to replace the fan clutch.

Here's a posting on how to test youir fan clutch.

Testing for a bad Fan Clutch (Sachs and Behr)

white lancer · #6 08-26-2013, 08:15 AM

Ok thanks for this. Is replacing the fan clutch something that can be done DIY?

I just run the X5 up to operating temp and the radiator fan just free wheeled all the time. I could stop it with my finger. Even when the car was at 90 degrees the fan speed did not change.

How does the viscous clutch work? how does the fan speed change with engine temperature?

upallnight · #7 08-26-2013, 09:03 AM

You will need to get the special tool that holds the water pump pulley stationary and a 32mm open end wrench. To remove the fan clutch the threads are Left hand so you will need to turn turn it CLOCKWISE to take it off.

or if you are brave you can follow this Youtube video. Don't use a regular hammer, use a rubber mallet.

https://www.youtube.com/watch?v=VCxYYk8a2rk

I brought the special tool and can remove the fan clutch in about 5 minutes.

TerminatorX5 · #8 08-26-2013, 09:04 AM

the electric fan kicks in with the AC going on full blast and the other criteria being met - i had either posted it myself or saw someone else post the detailed info about the AUX fan... if you have INPA, or DIS or GT1, you should be able to test the fan.

it operates via Pulse Modulated Wave (PMW) signal, and not direct 12 VDC - the 5% and 95% of the wave are reserved for the testing purposes and the spectrum in between is the operational voltage... the PWM modulates the voltage in a manner of ON/OFF fashion, so the periods of ON are longer or shorter than the periods of OFF, and thus the speed of the fan is regulated... the PWM is used in many other things inside the car, such as Brake Force Distribution lighting in the facelifted models...

speaking of the newer/older models - in the older models (i think either very early E53 or pre-E53) the AUX fan was controlled by a stage resistor array similar to the FSR in the airconditioner, and was always giving the problems...

The AUX has been moved from the front of the radiator to the back of the radiator on the newer models, as the placement in the front collected all the road debris and the bugs and essentially was killing the electrical motor by physically jamming the fan...

white lancer · #9 08-26-2013, 12:25 PM

Am I right in saying that you should not be able to stop the fan from spinning with your finger when the engine is being revved and is at working temperature?

If the fan clutch was good then it would give a lot more resistance than this?

I have just revved my engine at 4000 rpm when the engine was at working temperature and was able to stop the fan with one finger?

upallnight · #10 08-26-2013, 06:35 PM

After the engine is at normal operating temperature or above, is the only time that the "rolled up newspaper" test that many people talk about should be performed! Take some newspaper and roll it up into a long narrow tube. Be carefull, keep hands and fingers away from the fan while performing this test! With the engine at full operating temperature and idling, take the rolled up paper and insert it on the back side of the fan and try to reach the hub of the fan avoiding the blades until close to the hub. Push the rolled paper at the fan increasing the friction to the hub area of the fan. If the fan can not be stopped easily this is the fourth good indication, if it can be stopped the clutch is defective and should be replaced. Again, this test can only be performed when the engine is at or above full operating temperature.

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