[aerof16]

Originally Posted by meowmer

Got it. Thank you so much!

Does the sound go away if you press on the brakes?

[meowmer]

Originally Posted by aerof16

Does the sound go away if you press on the brakes?

Hey!! I didn't see the second page of this thread. Sorry for the late reply.
No, the sound doesn't go away if I press on the brakes. The sound stays when decelerating. It's really loud between 65 and 80

[Warp Ten]

Have you had an opportunity to have your rear differential checked? Over the years with older cars I have found that noises in the rear on deceleration usually pointed to a problem with the differential, either some gear misalignment or a bearing issue. But that was mostly on older Corvettes. --Bob

[LittleBlue]

I'm getting my diff fluid changed this weekend at 31K miles. It is preventative as I've had two diffs go out on me in the past on a different vehicle, 1st one went out at 65k!

Heard it's common as most never change the so called 'lifetime fluid', this is a breakdown waiting to happen if you don't maintain it.

Both instances in the past were howling or whining/whistling sounds when decelerating and not grinding noises, hope this brings some comfort to you. At that time (2014) to replace the diff was around $3.5K at dealer, the second one I went with a used one for $2K installed in 2019 then sold it.

[meowmer]

Originally Posted by Warp Ten

Have you had an opportunity to have your rear differential checked? Over the years with older cars I have found that noises in the rear on deceleration usually pointed to a problem with the differential, either some gear misalignment or a bearing issue. But that was mostly on older Corvettes. --Bob

I'll get it checked today. Will keep you posted!

[meowmer]

Originally Posted by LittleBlue

I'm getting my diff fluid changed this weekend at 31K miles. It is preventative as I've had two diffs go out on me in the past on a different vehicle, 1st one went out at 65k!

Heard it's common as most never change the so called 'lifetime fluid', this is a breakdown waiting to happen if you don't maintain it.

Both instances in the past were howling or whining/whistling sounds when decelerating and not grinding noises, hope this brings some comfort to you. At that time (2014) to replace the diff was around $3.5K at dealer, the second one I went with a used one for $2K installed in 2019 then sold it.

Oh wow! This car was always serviced at a BMW dealership but carfax doesn't show any change of diff fluid. I really hope I just have to change the diff fluid

Talking about lifetime fluid, do you think I should get transmission oil changed as well? Or should I wait till it hits 100k?

[LittleBlue]

Most likely never changed as it is not a dealer item to change.

One way to diagnose is to hoist it up at a shop and have someone put it in drive while the other person listens where the noise is coming from below

[meowmer]

Originally Posted by LittleBlue

Most likely never changed as it is not a dealer item to change.

One way to diagnose is to hoist it up at a shop and have someone put it in drive while the other person listens where the noise is coming from below

I'm getting it checked today. I'll keep you posted! I just hope it's not too big of a repair. This is my first BMW (got it very recently) and I'm absolutely loving it so far.
What do you say about the transmission oil?

[LittleBlue]

Differential fluid change update! I just finished changing my differential fluid at 31K, I'm surprised to see the old fluid being so dark, the new BMW Hypoid G5 oil is the color of olive oil. I highly recommend that you will change it sooner than later, I've gone through two differentials in previous BMW's, so highly recommend this change, maybe at 20K even! .

[meowmer]

Originally Posted by LittleBlue

Differential fluid change update! I just finished changing my differential fluid at 31K, I'm surprised to see the old fluid being so dark, the new BMW Hypoid G5 oil is the color of olive oil. I highly recommend that you will change it sooner than later, I've gone through two differentials in previous BMW's, so highly recommend this change, maybe at 20K even! .

Oh wow!
Do you have links to the diff oil? Also, I'm still waiting to get my car checked. I'll give you an update - hopefully today.

[meowmer]

Originally Posted by LittleBlue

Differential fluid change update! I just finished changing my differential fluid at 31K, I'm surprised to see the old fluid being so dark, the new BMW Hypoid G5 oil is the color of olive oil. I highly recommend that you will change it sooner than later, I've gone through two differentials in previous BMW's, so highly recommend this change, maybe at 20K even! .

So, I got it checked and the rear diff fluid had some metal pieces in it. I'm replacing the fluid. Then the rear Flex Disk was terrible. Here's a pic -
I'm replacing both flex disks. Hoping for the noise to be gone.

[LittleBlue]

Who's doing the work and what will it cost?

[meowmer]

Originally Posted by LittleBlue

Who's doing the work and what will it cost?

Dealership. And I'm not sure how much yet

[SAINTZK1NG]

Any update on this meowmer , I have a similar sound but accelerating and it starts around 1500 rpm but goes away over 2000rpm. Going to replace my guibo (flex disk) next weekend and hope that fixes it.

[CMK]

That flex disc looks like it's still within spec. It needs to look worse for BMW to recommend changing. HAVING SAID THAT, there's tons of anecdotes from people replacing flex discs that look like yours and reporting a huge difference in smoothness and power delivery.