nuge

I recently purchased this car with about 68,000 mi. Soon after I started to hear a whining noise coming from the back. Kept an eye on it and noticed that it was getting louder and louder as I put more miles on the car. I decided to change the rear differential fluid. When I drained the old fluid, it looked pretty clean and there was no pieces of metal or anything else to indicate a problem with a differential. The noise continued. After some research, I realized that the rear bearings were leaking. So I had those replaced. That was a royal PITA. There's a thread in this forum about the fact that the original bearings are no longer available. But thanks to one of the members here, I found an aftermarket company that has them. I was hoping that this would resolve the problem. But it did not. I contemplated the fact that it may be the tires but the more I test drive it, the more I'm convinced that there's something going on with the rear differential gears. It's not my daily driver so for now I'm going to park it. Does anyone know if the rear diff for the SL65 is shared with any other model.

ldeem

I would have it rebuilt before putting in a used unit.

Are you sure the noise is from the center differential and not wheel bearings?

I don't know about MB limited slip but if it is limited slip they often take very specific rear diff fluid and additives.

mrvedit

A bad differential often makes different noises (or no noise) depending upon accelerator, decelerating or cruising. If always the same noise, I would suspect bearings, but of course there are bearings in the differential too.
Can you share where you got your rear bearings and their part number?

EDIT: I found all the part numbers in this post: https://mbworld.org/forums/sl55-amg-...group-buy.html
The SKF is available for aboutt $250, The Timken is over $500 on Amazon.

cdk4219

All the Mercedes I have ever owned, the rear diff has never been an issue, if it is, I would have no problem buying a used diff instead of having someone try to rebuild something that is rarely done.

nuge

Like I mentioned in my original post, I did replace the wheel bearings. I've reached out to a lot of different shops who work specifically on Mercedes-Benz or rear differentials. None of them have ever rebuilt the differential for an SL65. My understanding is that it'sdifferent than any other model. I know the differential comes with an intercooler because I've seen it mounted on the rear diff housing. Finding a used one is next to impossible.

nuge

I've had bad wheel bearings on other cars so I know what that sounds like. But since this was my first experience with a Mercedes, it was hard to tell what the problem was. But after inspection of the wheel bearings, it was obvious that they were leaking pretty bad. But as I had mentioned before, I replaced them and it did not solve the problem.

Yes, this is the post I was talking about. I purchased the SKF ones.

nuge

I agree. In speaking to some of the shops that specialize in older Mercedes-Benz, not any joe can rebuild the rear diff for a SL65. I reach down to a couple of dealerships and they also confirmed that brand new rear diffs are not available. All the ones that the dealership sell are rebuilt. But they are rebuilt by Mercedes-Benz.