whining noise in my car

[JuN14sCR]

i am just wondering if anybody has experienced the same whining noise as i. while driving down my street at 20mph in second gear, i let off the gas and hear this high pitched whining noise. after i pressed the gas, the whine fadded away. has anybody experienced this same problem? should i get this checked out at the dealer?

[MarvelPhx]

Where does it seem to be coming from? The rear differential can emit a whine during coasting.

[JuN14sCR]

yeah, it is coming towards the back in the center. is this something i should worry about?

[MarvelPhx]

No, mine does the same thing. I don't notice it much since my radio is always on. If it really worries you, take it to your dealer. I do remember seeing a TSB on the subject.

I get the same thing, what do you think it is? Do you think its a recalled part in the engine? I never noticed it until i started to warm up my car, and the radio off. What could it be?

[MarvelPhx]

What you are hearing is the ring and pinion gears in your rear differential. When the vehicle is coasting, the wheels are basically providing power to the transmission. This ring gear teeth in your differential have two different angles for the "power" and "coast" sides. It is fairly normal to have a small amount of noise during coasting.

If the noise is too loud, uneven, or "pings", you should have it checked out by BMW. I know there is a Techinical Service Bulletin on noisy rear differentials for early model E46s. Check with your dealer.