E83 Rear End Noise???

[Bdevil]

I'm helping sort out my niece's 2005 2.5L w/ 139k miles before she takes it back to NY for the winter. Originally it had a noise coming from the back underside that sounded like the Mind Flayer with indigestion. Replaced the rear drive shaft (Dorman) and guibo (MeyleHD). New tires (General G Max AS-05) went on and I took it out on the highway for a test drive. Side note I was amazed how high the 2.5 RPM's were at 80 MPH, nearly 3k! All of the original noise seems to be gone, now I'm hearing something new in the rear when I'm off the throttle. It seems to be a bit of a whining sound. Don't know if this is a wheel bearing, rear diff bushing or something else. In town, side to side turning does not seem to cause any noise, this is all straight line. Any thoughts? TIA

[jclausen]

If it's a wheel bearing the sound will change when the car is turning, loading the bearing then turning the other way will unload it decreasing the sound or diff

[X3456]

When was the rear diff fluid changed...if never or I don't know...it's time at 130k on the clock.

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[Bdevil]

When was the rear diff fluid changed...if never or I don't know...it's time at 130k on the clock.

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Changing front and rear diff fluid is next on my punch list, xfer case and transmission have already been done. Fluid from both did not look that bad which makes me think both had been serviced at least once before.

[bdiefAZ]

Check the rear differential mounting bushings for play

[Bdevil]

I presume you mean #10 shown in this image. There are many others including #2 & #3. Do they all need to be replaced at the same time or is #10 the usual point of failure?

https://www.realoem.com/bmw/enUS/sho...diagId=33_1199

[bdiefAZ]

Bdevil, you are correct, #10 is usually the culprit. See my experience with that here:

https://www.bimmerforums.com/forum/s...-bad-on-my-e83

[Bdevil]

Thanks Brian, great write up.