Hello all,

I have a 1980 300SD that whines while the car is moving. It has been that way since I purchased it. When the car is moving, there is a hum, sounds like it comes from the rear wheels but I can not be sure, since I don't have anyone to drive it for me while I listen.

I know it is not transmission related because when I put the car in neutral (while moving) , the noise is still there.

Applying the brake does not make any difference.

The noise is not a grinding noise, but the best way I can describe it is an electric car, electric motor, ect. Makes that humming sound.

After some research on the subject, I see it has also been asked to feel the wheel after a drive, and if its warm or hot, there may be a stuck caliper. I do not feel any of them getting warm or hot.

I tried also jacking the car up and trying to move the wheels by hand, and I have not been able to hear it then.

I am thinking wheel bearings, does that sound like an accurate diagnosis? And if so, is this something that needs to be done right away to avoid other problems?

Thanks and Happy Holidays!