Questions and Answers
Whining BMW
Q. Hi, I have a 1993 BMW 325i sedan with 71,000 miles on it. I have the whining coming from the rear differential. and I changed the differential. oil twice and still has the whining noise. My question is, is there a bearing in the differential? If so, would it be expensive to fix?
Thank You,
GlennA. There are several bearings in the differential which could be making the noise you describe. It is also possible the gears could be making the noise as well.
Usually changing the fluid will not help the noise. BMW used four different differentials in that car and if you have a limited slip differential, you need to be sure that the right gear lube is used. For a limited slip differential you need to use a GL-5 gear oil for limited slip differentials or a Hypoid gear oil for limited slip or Traction-Lok differentials. There is a tag on the differential that will tell you what it is and you can look up the required fluid for it.
Replacing bearings and gears in a differential is a long involved process. Not so much replacing the parts, but making the calculations and adjustments. If the noise is not real bad, I would say just live with it. If it is objectionable, then you would be better off getting a used or rebuilt unit. By the time you pay for the one you have to be rebuilt, you can get a rebuilt unit already to go.
A rebuilt non-limited slip differential from BMW will run about $1300.00 and a limited slip differential will run about $2500.00. Of course you can get them cheaper from an aftermarket supplier.
Additional Information provided courtesy of ALLDATA
