Squealing noise while driving.

I look around the forums and trying to find what the problem is but to no avail. Anyways, I have a 98 BMW 540i which I bought last November and been pouring money into it (mechanical work). It's driving good now but need a little more fix to it (O2 sensor replacement ... don't know which one). Just got front brake pads and front brake rotors fix last week (cost about $651) which I thought was the cause of the squealing/squeaking/tea kettle whistle sound. Nope, it wasn't. The sound still happen when I'm driving at about 25mph and up. It start to stop when I hit the brakes. I took it back to the place where I got the brakes fixed and took the mech guy for a drive and he can't determine the problem also. Thought it could be the back bearing but I notice the sound was coming toward the middle front of the car where the air vent is (the engine part maybe?). I try shutting/closing the front vent but still I can hear the sound. I don't know where or what is making the noise but its annoying when I'm driving and hearing that sound. It's doesn't happen all the time. Sometimes it happen when I hit a pothole or when I'm making a right curve exit from the freeway. Like I said, it happen when I'm driving 25mph and up.

Anyone have any ideas on what it can be. I might have to take it to the dealer and have them check it out to see if they can determine the problem.

Not sure if you're talking about the noise from the AC/heater blower fan. If you turn off the fan completely, do you still hear the noise?

My guess is that one or more of the brake pads is in slight contact with the rotor. That's why the noise goes away when you press the brake pedal.

The pads and calipers must be lubed with anit-seize compound on their sliding contact points with the caliper.

Was the mechanic a BMW specialist?

Hard to pinpoint from your description. Since this happens only while driving, at certain speeds, and is exacerbated by certain wheel turns at speed, I would look to your wheel bearings.

Originally Posted by scott0357

Not sure if you're talking about the noise from the AC/heater blower fan. If you turn off the fan completely, do you still hear the noise?

Yes, I turn the fan off completely and still hear the noise.

Originally Posted by edjack

My guess is that one or more of the brake pads is in slight contact with the rotor. That's why the noise goes away when you press the brake pedal.

The pads and calipers must be lubed with anit-seize compound on their sliding contact points with the caliper.

Was the mechanic a BMW specialist?

Yea, they specialize in European car (BMW, Mercedez, Audi, Volvo etc.) I might ask the mech guy to lubed the pads and caliper when I take it in on Monday again.

Originally Posted by Waveho

Hard to pinpoint from your description. Since this happens only while driving, at certain speeds, and is exacerbated by certain wheel turns at speed, I would look to your wheel bearings.

It doesn't happen all the time but it does happen and its annoying. Wheel bearing is what the mech guy gonna look at on Monday. But than, it could be anything.

Forgot to mention, the mech guy ask me to (when I'm driving and I hear the sound) put the car in Neutral to see if the sound still there. Yes, it still sound when I put the car in Neutral while driving. I don't know if that suppose to help trying to figure out the problem.

Is it kind of whispering?

does it change pitch when the engine is revved up? does it change pitch when you speed up? Most likely this isn't your problem, but my rear e brake drum shoes came loose and the retaining spring dropped into contact with the shoe/drum. It squealed and clicked like crazy. I've also heard of people 'bedding in' the pads by driving to high speed and holding the brakes until they fade. Seems like a great way to use up miles of pads and warp your rotors, but it might fix the squeak.

Originally Posted by rashid

Is it kind of whispering?

I would say a little but some times it can get loud as a Tea Kettle whistle. I can hear it when I open the window also. One day, the sound seem to be coming from the right rear side. The next, it seem to be coming from the front middle or right rear. Haven't determine what or where its coming from yet.

Originally Posted by helpmyfive

does it change pitch when the engine is revved up? does it change pitch when you speed up? Most likely this isn't your problem, but my rear e brake drum shoes came loose and the retaining spring dropped into contact with the shoe/drum. It squealed and clicked like crazy. I've also heard of people 'bedding in' the pads by driving to high speed and holding the brakes until they fade. Seems like a great way to use up miles of pads and warp your rotors, but it might fix the squeak.

I haven't notice a change in pitch but the longer I drive, the louder it gets. Like, when it start it will be soft but get louder and louder. Doesn't really depend on the speed but how long I been driving after I hear the sound. Sometimes, it goes away when I hit a bump or pothole but seem to come back when I hit it again.


Hopefully, someone can help me determine the problem; that way the mech guy know what to tackle. I want to get it fix before I go trade it in for a 740 or 750 .

I am having the same problem. i have a 2004 x3. I hope someone can help us. Mine comes after driving a while and seems to be in the front left part of the car.

Might be a hole in the intake boot.

Drive me nuts...why don't you just 'throw' more money at it till it goes away! Your mechanic, should have told you upfront that is not your problem... the whistling could be caused by, bad belts, missing jack pad, bad fan pulley...etc...so get a real description....and get it to a real mechanic or a real repair shop and have them take a look at it. These are cars, not space shuttles!

funny u posted this squealing noise im chasing down the exact same problem on my 540i--did u ever figure it out what causes that annoying noise? mine is in the front passenger wheel well

Having same irritating noise, but it starts when i apply the brake. Gets really noisy after long trip, but then goes away.

Hey everyone, I have a 2000 540i and have also experienced this "tea Kettle" whistling noise coming from the center console...so I used the ole common sense approach. I had my son pin point the noise origin while I was driving (Rear Vent, center console). Sooo put 2 & 2 together, sound coming from a vent…is there a fan in there? I looked it up on realoem (http://realoem.com/bmw/) under “heating and air conditioning” you’ll see that some models came with a rear blower (fan) and regulator…as you speed up or down the regulator adjust the fan speed. I haven’t taken mine out yet, but I bet you a beer that the blower is the culprit to our mysterious squealing noise! Spray some WD40 on that Bi!@# ....lol I’m going to take mine out this weekend…