What's this noise?

Question

It sounds like a high frequence virbration (similar to revs), the pitch increases with the speed of the car.

Noticable (above other noise) at about 35mph, then gets louder and higher as speed increases.

Dipping the clutch, accelerating or cruising has no effect on the noise, so I'm guessing its coming off the wheels/suspension?

It sounds like its coming from the rear of the car.

I dropped the tire pressure for the recent icy/wet weather., but putting it back up also made no difference.

I did do about 1200 miles two weeks ago and 900 miles last week. And about half of that was in wet weather on gritted motorways. I'm guessing something is badly worn as a result.

1994 BMW 320i coupe.

Questions · Accepted Answer

Jacking the back up and spinning the wheels by hand would be a decent place tostart.

Josh Assing · Answer

I'd check your drive shaft balance if you have a balance AND noise issue... just a guess tho.

definately check the oil levels (tranny, diff) and jack the car up and spin both rear tires to be sure the bearings spin freely & there's no play..

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JimV · Answer

Sounds like a bad wheel bearing.

Jeff Strickland · Answer

My guess is that a wheel bearing is going/gone out. Have it checked out before it becomes a catastrophic failure and leaves you stranded.

Lordy · Answer

Putting it in the Garage Monday morning. The Inspection II light also came on , so I guess I'll have to grease up :).

I have to do about 20 town miles on Sunday. Hopefully it will last me until Monday !

Lordy

Paul Martin · Answer

Is your car a manual?Does it make the same noise if you are not in gear and just rolling along in neutral? (note: you have to actually be in neutral - disengaging the clutch just disconnects the transmission from the engine - if you are still in gear with the clutch disengaged, you will still hear the whine)My car (2004 E46 318i manual) has a transmission whine, particularly in the lower gears - it is normal and nothing to worry about. If this has just appeared then it is probably not normal!Paul

Jeff Strickland · Answer

20 miles shouldn't be the make-or-break on this.

R. Mark Clayton · Answer

Could be the differential.  Is it more noticeable on sharp corners, especially in reverse?

JimmyG · Answer

Bingo!

Doki · Answer

I'd be a bit riled if I'd just spend a fair wedge on a new BMW and it had a whiney gearbox from fresh...

Paul Martin · Answer

It is not fairly quite and only noticable in 1st and 2nd gears with the window rolled down and a wall next to the car so the sound is reflected. Otherwise I can't hear it at all.

If it were louder I sure would be annoyed!

Paul

What's this noise?

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