Odd High Pitch Rotational Noies in Rear Wheels
 

I have a 2004 325i, it has about 70,000 miles, and I am hearing the strangest noise out of the rear of the car. Its is a very high pitch and sounds rotational. The best way to describe it is like a mosquito's buzzing. The noise is always present after 5 - 10 minutes driving, when its dry and 30 - 45 minutes when the roads are wet. The pitch does not seem to change with the wheel bearings are loaded, when the brakes are applied or when the parking break is slightly applied. The noise gets louder as speed increases, but the pitch does not really fluctuate. It usually goes away under 5 mph, and is exceptionally loud when driving between 25 and 40 along barriers or fences (with the window down). Over 50 it becomes hard to hear as wind/engine/tire noise drowns it out.

I have checked the brakes, the rotors, the parking break shoes, the U-joints, the bearing seals, and the diff. When the car is up in the air and the wheels spinning, the noise is not present. I've been to 3 shops, and the only thing I was told was that the parking brake shoes were seated incorrectly, they ground them down, and put them back in. Supposedly curing the problem, BUT as I drove it home the noise reared its ugly head and continued to taunt me :(

Everyone who hears the high pitched whining seems to agree that it is not a serious problem, and I concur, but it is probably the most annoying noise I have every heard the car make.

If anyone has experienced this, or has any advice on what to check next, PLEASE jump in and let me know.

Thanks All
-J

The pattern of symptoms does not fit, but your description of the sound reminds me of the buzzing sound we started hearing from the rear of our '04 330 about a year before the fuel pump failed. That noise was most apparent when the car was sitting still in the driveway idling. It came and went over a year and 10k miles and we never knew what it was until one evening the wife walked out of the grocery store and the car would not start.

got whining noise from rear of my 99 318i, let you know when i get to the bottom of it

I had same noise in the front, rotated tires and now the noise is in the rear,turns out I need new tires. My 2cents GL

HyeTide's comment reminded me that both my 2004 BMWs are very prone to transmit road noise to the cabin when the rear tires are worn. Mine both have factory 'sport' suspensions and 17" wheels. The '04 330i is worse than the '04 325iT, but both do it much more than my two '97 328s. The problem is more a function of road surface and tire condition than of time driving or speed. My cabin noise level drops dramatically when I put on new tires, then gradually increases as the tires approach the treadwear indicators.