01 740i - Noisy fan or fan motor

It just started up and it's loud enough where I can hear it in my car with no music. I opened the hood & it sounds like it's in the very front of the Engine compartment. I'm very stupid with this kinda stuff so I apologize for the questions but this kinda worries me.

My SES light pops on & off all the time too but recently it turned on and after I shut my car off the noise started when I started it up.

There are two fans in the front of the motor. One is the radiator fan which connects to the water pump, and the other is the electric auxilary fan which should only turn on when the A/C (snowflake) switch is lit. If you turn off the climate control, does it still make a noise?

I just had a buddie look at it and he said the Electrical Auxiliary Fan was at high RPM's. I don't see why though. I replaced it for $1,000 at BMW 10 months ago (9,000 miles).

I turned AC off & the snowflake button wasn't pushed on. The noise still remains. I'm going to **** a brick if I need to replace it again.

The auxilary fan should not be running if the A/C is off. If the fan is running then the fan is not the problem, whatever is giving it the signal to run is the problem. That sounds like an electrical issue, but unfortunately, I have no idea what it is.

The Auxiliary fan had a relay which drained my battery in 1-2 days until I fixed it in January, 2010. I just hope this is just going to make noise & not cause an electrical drain or any severe problems.
Does anyone know how to fix this because I want to get an idea of the repair cost because the dealer sees dollar signs when I come in for repairs. I just hate getting ripped off.

Hey Balance,
I think I found my fan issue. I checked my coolant level last night and the tip of the dipstick is close to 2 inches from the rim where the cap goes. Is that enough to turn the fan on? Should I just add coolant?

You should add coolant to the system but I'm not sure that it is the cause of your fan issue. The dipstick should be level with the top of the expansion tank only when the coolant is cold.

Your radiator fan is what cools down the coolant in the radiator, which cools down the motor. The auxilary fan is used to cool down the freon in the A/C condenser to change pressure in the A/C system and make the air that comes out of the vents cold. The auxilary fan should only cut on when the A/C button is illuminated.

I'm not sure if the aux fan will cut on in the event of an overheat, it might, but if your motor is not overheating then that is of no use to you. If you took the car to the dealer less than a year ago and paid to fix the same issue, you should go back and see if they will check it out for free. Tell them that you shouldn't have to fix this issue on a yearly basis and maybe they will check it out for you.

Hey Balance,
might this be the problem I'm experiencing?
(Viscous Fan. The Viscous Fan is mounted on the water pump shaft and is driven by the main belt from the crankshaft pulley. The assembly consists of a temperature-dependant viscous-clutch driven from the pump shaft that drives a large plastic fan. When the clutch is cold the fan idles and can be stopped with a rolled-up newspaper (the usual test), once the clutch is hot the fan is driven with a much greater torque and produces a great deal of air-flow. The usual problem is that the clutch fails and the fan cannot produce enough air-flow. The fault will show itself when the car is stationary when it will rapidly overheat. The temperature-rise is usually halted by the the auxiliary fan (A/C fan) which will operate independently to the A/C system when required. Once the car is moving the temperature starts to drop. A more unusual problem is that the clutch seizes, this is first noticed by large whooshing noises when the car is revved-up. Replace the viscous coupling immediately if this happens as the fan will disintegrate and this can cause all sorts of damage including big holes in the bonnet!)

My temp gauge however has never reached over the half-way mark.

The viscous fan is the radiator fan. Is the noise coming from this one, or the electric auxilary fan in the front of the condenser?

The radiator fan runs off of a clutch that can seize up and cause the fan to run at the same rpm as the motor and like the article stated, the fan, which is plastic, can blow up and take out the air box, radiator hoses, hood, or anything else it hits.

Try this, open the hood, place you hand on the radiator (viscous) fan, and try to turn it in a full turn in both directions. If it feels like it is catching on something or feels really rough or grainy, then that is your problem. If it feels smooth like it is riding on gel, then it is probably OK.

Does the electric auxilary fan cut on as soon as you start the motor in the morning when the motor is cool, or later on? Have you unlocked the OBC on the dash to check the actual temperature of the motor? When the aux fan cuts on in my car, I can barely hear it from the inside when my windows are down. On some cars there is a high speed, and a low speed for the auxilary fan. If it is making a loud noise while running, and there are indeed two speeds to the fan, then it is probably on high speed and you should try to find out what would send a signal for this fan to run on high.

Oh, and when I said to turn the radiator fan by hand, I meant while the motor was OFF.

Well it's not the radiator fan. I'll just take it to BMW and see if the can diagnose my problem because it seems like an electrical issue & I hate electrical

However when my engine is cool it turns on when I start it in the morning and stays on until 1-2 seconds after I turn off my car. I can hear a bit with no music & my windows up but it sounds like a jet engine when I put my ear up to the bra grill in front of my car.

Thank you for your help though Balance and excuse any stupid questions I may have in the future.

The fan doesn't turn on anymore, hasn't for the past 2 days so I think I'm in the clear.

However I am guessing it's an electrical issue because other wierd things have popped up in the past like after washing my car one day I tapped the windshield wippers to wipe my window once and it kepped wiping for 30 seconds and stopped in the middle of my windshield. But all is good at this point.

If after washing your car, you experienced electrical problems, I would be checking the ECU compartment under the hood, and seeing if it was getting flooded with water. If it is, this issue should be taken care of immediately.