w201 differential whine
 

Hello everyone,

I was just wondering your thoughts on a whine I have in my rear diff. I did some reading and some people say using a heavier oil might help quiet it down. Right now I have 85w90 or 75w90 I can't remember. Some of the threads I saw seems to indicate using 85w140 would help quiet it down a bit.

Thoughts?

I've heard oil can help..redline makes one. from my experience whine is usually from the pinion setting in the differential. It won't harm you but annoying. I assume you have serviced the diff oil.? You could replace the rubber differential mounting. I think there was a lot of sound deadening behind the back seat, you might check that too. Are you sure it's a differential noise? Not in the axle or brakes? Noise can transfer.

The diff has fluid was changed out at 190k. Its only on decel/coast. Nothing on accel.

So that makes me think differential. I can't remember I put in it...

if it's on decel/coast then that's the gear noise. like i said noise is transfered so changing the mount might help, and also check the rear seat isolation first.