Update for the group on our Model Y - TL;DR is they've replaced the front drive unit and the noise is gone, just as it was with my model 3.
We had brought the Y to the Service Center on April 11th and they had determined it was the rear drive unit making the noise. This had seemed odd to me as the noise sounded identical to the issue that resulted in a front drive unit replacement on my Model 3. We were told they needed a few weeks to get the part in and they scheduled us to come back on May 1st. Initially I was told they'd need the vehicle until Tuesday, but when dropping the car off they said this was a bigger job and they needed it until Thursday. As the days went by I noticed the vehicle still hadn't moved out of the "preparing" stage and decided to call in for an update. Found out they still hadn't started work on my vehicle but committed to doing the work Thursday evening and that I'd have the car back on Friday. To my surprise I received a notification at 4:45PM Thursday that my car was ready for pickup! Before heading down to the SC I checked the invoice in the app and saw they closed out the issue as "could not reproduce". I was extremely frustrated and called the SC. Recap of what I learned was:
- Since my April 11 appointment Tesla has changed their internal policy and now requires that engineering at corporate approve all drive unit replacements. While the SC had previously determined mine was due for a replacement, they now had to validate that with corporate.
- This is supposedly due to an internal report stating that the company had spent $30M on drive unit replacements in the past several months only for the issue to not be resolved so they're limiting the replacements they do while they look to determine the real root cause of the issue.
- They drove my vehicle multiple times and stated they could not reproduce the noise and had even taken audio recordings and sent in to engineering to confirm there was no noise that was out of spec.
They said I was welcome to come back in and go on another ride along with a tech. I told them I had already done this and the vehicle was put up on a lift and the issue verified which is why they currently had the vehicle in the first place. Finally I got them to agree to keep the car overnight and test it again in the morning.
Friday AM I called in and spoke to a tech who told me they now HAD verified the issue (thank goodness!) and that they were waiting for engineering approval. While chatting through next steps the tech told me that there was an internal service bulletin about the issue which states the issue becomes more pronounced the further from 32F. This may explain while they didn't hear the issue the prior evening when it was close to 80F vs 50F in the morning the next day. They also confirmed that it was indeed the front drive unit. No idea why the previous tech had been so confident it was the rear...
In the end new part was ordered, installed Monday evening, and we picked the car up on Tuesday. Glad to have the vehicle back and it is finally quiet when driving around town for the first time since we picked it up. Happy with the outcome, but a painful journey to get there!