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Humming noise: is it normal?

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Its my first time to own a bimmer. I don't know how it sounds when moving. However, I noticed that at low speeds, there is a humming sound that seems to come from the wheels. As it picks up speed the humming disappears, My mechanic convinced me the bearings on the rear wheels required replacement. I purchased new ones at high cost and replaced them. But I have not noticed any change in the humming! Was I ripped off? My mechanic may tell to replace the front bearings as well without any success and a big hole in my pocket. I have not driven any other bimmer so I have no idea how good bearings work! Any help will help.
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Sounds like bad wheel bearings or your tires are just worn. I'd go with the cheaper route first and maybe try some new tires.
Thanks MalibuMafiaV. Appreciated. Perhaps I should start with replacing the tires first. I was told by the wheel balancing guy that they were uneven. If the humming doesn't disappear then I may have to replace the front wheel bearings as well. Could the quality of the bearings also be a problem? BMW parts are hard to come by in our area!
First off...repalce your mechanic! Humming from the front caused y bad rear bearings??!!!

My first guess is tires. I have my winters on now and because of the tread, I notice lots of noise at low speeds. ALways go with the simplest solution first (ask me how I know). Try swapping around wheels and/or changing tires first. bad balancing shouldn't cause noise but tread wear could.

You should be able to test the bearings before committing to replace. With the car raised, place a hand at 12:00 and one at 6:00 and push/pull the tire. IF there is movement, your bearings are bad.

uneven brake wear could also cause a rubbing/humming noise. Pull the pads and look to see if you have abnormal wear patterns or ridges on them and/or the rotors. THis can happen without a noticeable decrease in braking and it's an easy and cheap thing to eliminate from the equation.

Also, with the brake caliper and pads removed, you can spin the rotor and if the bearings are bad, you should be able to feel/hear something. May want to borrow a merchanics stethoscope as if they are just starting to go, you may not hear it without one.

Good luck.
If you can lift the car another test for a bad bearing is to simply spin the tire with your hands and listen closely, a bad bearing makes a distinctive metal on metal noise while spinning.

Apart from that, a worn wheel bearing usually gets louder proportional to your speed going up :confused: I would run from that mechanic...
Thanks MalibuMafiaV. Appreciated. Perhaps I should start with replacing the tires first. I was told by the wheel balancing guy that they were uneven. If the humming doesn't disappear then I may have to replace the front wheel bearings as well. Could the quality of the bearings also be a problem? BMW parts are hard to come by in our area!
I vote tires, happened to me on more than 1 cars. You can try this: rotate your wheels and see if the noise is the same. If the noise is still there but sounds different and/or less I say tires.
Thanks for the advice. Will pass at the servicing bay and get the car lifted so I can try out each option. Probably, first replace the tires coz they all seem worn down. Actually someone warned me about this mechanic but I didn't listen. They are more interested in selling their parts than diagnosing and fixing the problem!
The mechanic did not even test whether the bearings were faulty before removing them! I did not see him spin the wheel around or push/pull to determine if they were faulty. He drove around and simply concluded they were the culprits and wham... they were off and a big bill to top it off!
Always a good idea to post here when you have issues and before you go to a mechanic. Lots of guys that have "been there and done that" and you can go to a mechanic knowing what to expect and what to watch out for.

Good luck.
The mechanic did not even test whether the bearings were faulty before removing them! I did not see him spin the wheel around or push/pull to determine if they were faulty. He drove around and simply concluded they were the culprits and wham... they were off and a big bill to top it off!
Very good advice. As they say "there is always the first time"
I have had tires that got so loud, you would think I had bad wheel bearings or differential bearings. I bought new tires and the car was quiet again. I am not saying this is your problem, but it is a possibility.

:drive:
+1! Maybe it was cause they were the first batch sent over, but the Pilot Sport A/S Plus I first put on started to chunk off at the sipes and pretty soon were phenomenally noisy. After they were replaced by Michelin under warranty with Pilot Super Sports, silence is golden once more.
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