So the M has had some noise and a tiny bit of vibration I can feel mostly in the pedals, something rotational, coming from the front for a while now. It's most noticeable at about 45 or 50 MPH when coasting so the sound of the engine and wind noise doesn't drown it out. It does vary with speed. I replaced both front wheel bearings less than 10K miles ago with OEM parts. The tires have about 40K on them and are not showing any uneven wear issues. The car drives straight and doesn't pull to one side or the other. I took into an Infiniti dealership several months ago and they said the suspension was fine, although they did resurface the front rotors as there was a little brake shimmy at that time. Since the symptoms have gotten a bit more noticeable, I took it to a small local shop to see if they could figure it out. They used a stethoscope and determined it was coming from my transfer case. The case doesn't leak and is full of fluid (changed less than 6 months ago).

My question to the board - has anyone else had symptoms like this as a result of a bad transfer case or had to replace their transfer case? The tech said its very unusual for it to fail - car has "only" 132K. I suppose an internal bearing could be the culprit but just don't know for sure. I can source a used one on EBAY for a about $250 with shipping and they want $450 to replace it but wanted some input before spending $700 - $800 if that's not actually what it

Thanks in advance.

I would agree that this is a pretty rare repair. Having been here for many years, I can't say I recall many folks having to do it. Is there any troubleshooting steps in the FSM that can be done without a mechanic?

The Infiniti AWD system is very robust..
Of course anything mechanical can fail..

But I dunno... 40k sounds like a lot on tires.. they often fail internally long before the "tread wear warranty" is over and/or the tread shows excessive wear.. Unless they are a high end brand like Michelin and sometimes even then.. have you checked the balance on them?

And if its off.. re balance them and then check the balance again a week later.
If its then off again, your tire internals are falling apart.

Yeah I thought about the tires too. But they are only a bit less than than 4 years old as they have a born on date of Sept, 2016. They are Michelen Primacy's and I've had nearly 60K on a set of those before. I rotate every 7,500 miles. I just rotated them in the last two months and the sound still comes from the front end. No change at all from the tires. I'm just not convinced its the transfer case as I have not ever heard of one failing on these cars.

Re-reading your post - I've rotated the tires myself since I got the car in August of 18 - so they've never been balanced since I bought the car. I usually buy tires at Costco and they include free lifetime rotation and balance, but these were good tires with less than 20K when I got the car. I suppose it could be a factor, but I would think there would be more of a change when rotating and potentially uneven wear and shake in the steering wheel.