Diff whining

[Ryan_n]

2 weeks ago i started noticing a faint whining/screeching/metal grinding noise coming from the backend. I am used to the different sounds this car makes but this one was new and didn't sound right.

Took it to the dealer to diagnose and they came up with: "Spin rear wheel and found noise coming from rear diff. No leaks, oil level good, remove some oil and found metal debris inside and oil smell burnt." They ordered a new diff and it's been backorder for 2 weeks.

I have 25k km on the car, wondering if anybody else got a similar issue and what could've caused this? I read multiple threads about the rear diff, always thought it was quirky and made weird noises. Dealer told me I can still drive the car while waiting for the diff swap. Any risks breaking something else if I keep driving it?

Thanks for your help as usual!

[65fastback]

Yeah... Iam getting a bit of the same sounds ( 2016 33K ) out my rear diff. I have yet to take it in yet, monitoring it as of now to see if it gets any louder. Might do a drain & fill soon to see if that quiets it down.

[bsmf8x]

Originally Posted by 65fastback

Yeah... Iam getting a bit of the same sounds ( 2016 33K ) out my rear diff. I have yet to take it in yet, monitoring it as of now to see if it gets any louder. Might do a drain & fill soon to see if that quiets it down.

Update us if you don't mind as I'm at the same mileage/year and if I hear anything I wanna know if a fluid change would fix it

[65fastback]

I actually have a friend who is a mechanic at a BMW dealership, i’ll hit him up and see what he has to say and keep you posted.
I also have a warranty & extended maintenance on this car so I’m not sure I want to start doing anything to it yet.

[Ryan_n]

Quick update, dealership received the diff from Germany but turns out the new diff requires a new drive shaft (wasn't clear in the TSB). Have to wait another 10 days for the drive shaft to arrive, stuck in a 330 for now

[swagon]

Could you expand on the symptoms? Like when it was happening for example, thanks

[Ryan_n]

swagon First sign when I left driveway and I heard heavy knocking/grinding from the rear end that went away after a seconds of driving. Since then I always hear a constant whining noise. Took it to the dealer to check, they inspected the diff oil and found metal debris and the oil smelled burnt.

I know this car makes a lot of weird noises from the back when downshifting etc and we're all used to it but the constant whining at low speed is sign of something wrong I think.