F15 2018 50i -- subtle rumble / vibration at low RPM

[E34_BMW_525i]

Hi -- I have searched a bit for this and my thought, based on what I have been reading, is that it might be either the plugs / coils or the transfer case / transmission bushing. But maybe it is something else altogether, or maybe folks can weigh in on which one is more likely.

My 2018 X5 50i is still under factory warranty until late 2022, so I would like to try to nail this down soon-ish. Currently @ 37k miles.

The issue is most noticeable (or maybe only noticeable) when pulling away from a red light with gentle throttle. At low RPMs, I feel a subtle "rumbling" vibration in the drivetrain. I would not describe it as hesitation at all, and there are no sounds either, just a really subtle rumble feeling. The car is going 5-10 mph when this happens, so it's not the vehicle itself, it is in the drivetrain. And because I am accelerating gently, once it shifts to the next gear, I feel it again for a second as well. As soon as the RPMs rise, it's gone.

Really only feel it under 1500 RPMs in those first few seconds pulling away from a stop, in the first few shifts, and then it is not observable really.

All thoughts / input appreciated. Thanks in advance.

[tlow98]

Transfer case tends to yield similar issues. How does the car behave at a crawl in full like turning circles?

[Tomcat_F15_STL]

Original High Performance tires at 37k miles?

My guess is:



Tire Cupping.

[E34_BMW_525i]

Tires are close to new. Definitely feel it in the drivetrain.

I will try slow-crawl circles in a parking lot sometime soon.

If it is pointing to transfer case, is it a bushing, or what specifically related to the transfer case tends to fail producing these types of issues?

Thanks.

[tlow98]

The transfer cases have fluid that does accumulate wear. Then the friction discs get out of alignment.

99% of the time you just need to change the fluid and recalibrate the unit. This is like ~$500 service.

Don’t let the dealer make you think it needs to be replaced for $5k.

You can diagnose this by pulling the connector plug on the unit itself. If the issue goes away when you unplug you’ll know if this is your issue. Then just get it serviced.

If this doesn’t work you know you’ll have to look elsewhere.

[E34_BMW_525i]

Just following up here for the benefit of any others whose X5 experiences symptoms similar to what I described above.

I had the vehicle in for some other service and had them check. They confirmed that the transfer case was the source of the issue. I also suggested we try a flush and recalibrate, but apparently there is now a bulletin for this issue and the service manager told me that once they reported their findings, BMW NA approved replacement of the transfer case without hesitation (my vehicle is still under warranty). I wasn't going to argue with them since it seems better overall to go ahead and get a new one while I can in case it's a recurring thing (no need to wait for warranty to expire).

I haven't driven enough miles to confirm with certainty that it is 100% resolved, but my initial impression is that it smoothed out the exact rumbling / vibration that was experienced at low RPMs.

Thanks everyone.