M3 whining noise after differential seal replaced PLEASE HELP!

[tnsman83]

I just bought a 2003 M3 coupe. The differential seal needed to be replaced so I had that done. I just picked the car up from the mechanic (after hours) and drove it home and it is making a loud whining noise whenever I let off the accelerator (it's SMG). It does not matter what RPMs it's at, and it does not make the noise when I am giving it gas (but if i switch it into "0", AKA neutral, it will not make the noise while I am coasting)... ANY IDEAS? Thanks...

[Podmore]

If it only makes the noise while in gear with the drive train under negative load, it would tend to suggest that the source is the diff - if this was the only area worked on, then it almost has to be. My guess would be that the tolerances (crown wheel and pinion gear lash) have been put out of whack during the process of replacing the seal. Maybe the seal hasn't been put fully home (I assume it's the pinion seal that was replaced) or some adjusting shims have been left out. Whatever, take it back to the shop - it's their problem!

[BoominBenz]

It's probably no coincidence that after the shop worked on the diff, there is drivetrain noise. Go back and ask them to look at it (on their dime).

[bimmer_boyis]

That's going to be a fun one to fix. Im with podmore. Someone forgot to dimple the nut when taking the input flange off and now pinion depth is off. Sounds like too tight.

[tnsman83]

Thanks for the help guys... I brought it back to the shop and firstly they put the wrong diff. fluid back in when the replaced the pinion seal.

Also, the cause of the noise (from what I remember he said and in my non-technical words) was that they tightened the nuts back to where they were (they said they marked them and retightened to that point) initially but then they loosened them and tightened them to BMW specs (a certain torque) and the problem was solved.

Again, thanks for the help.