Thanks so much for your advise guys! I had a bit of a breakthrough last night after I ran the X5 for five hours straight mostly in traffic on a 101 degree Texas day…. The noise by that point was as bad as I’ve heard it, so empowered by my $4.99 Harbor Freight stethoscope I was finally able to recreate the sound while stationary by weighing down the gas pedal with the tire jack at around 2,000 rpm [link to video at bottom]. The only problem was I’ve never heard what a good vs bad bearing sounds like through a stethoscope. So for the components I could actually get to with the wand pretty much everything sounded like cacophonous ruckus. With the stethoscope off the screeching is so overwhelming (as you can hear in the video) that it sounds like it could be emanating from any part of engine (but almost definitely not the tranny).
I will say that although I was convinced the sound was coming from the intake system somewhere, by either power of your guys’ suggestion or actual observation, I am now almost convinced it’s a bearing as well. You can hear in the video during the parts where I rev the rpms or remove the jack from the gas pedal how the screeching winds up or down in a “circular” motion like it must be coming from something spinning rather than air being sucked in or through a small space (eg. intake or vacuum related problem).
Yesterday I also took your guys’ suggestions regarding turning the a/c off, putting it in neutral, shifting gears manually, seeing if the sound changes when I turn, but it all came back inconclusive… the only sure things are that it happens when the car is good and warmed up (30 mins+),and is triggered only by releasing your foot off the gas above 2000 rpms and will continue until you either come to a complete stop or accelerate again. Shifting, turning, a/c don’t effect it at all. I have noticed that when I’m idling uphill the noise is slower to go away once I come to a stop.
Anyhow, next step? Would you all agree I need to remove the fan and belt and manually inspect all the bearings along the belt route?
EDIT: I failed to mention last time that at the end of the video I included the results from the OBD scan performed right after I recorded the screeching. There’s like 12 faults and I’m sure most of them have been there since before the noise (I should probably look into a few of those). If you guys notice anything you’ve dealt with before in the codes, advice on that is greatly appreciated also.
*** the EGR or secondary air pump or something was deleted from this car ages ago, before my time if that makes a difference.
VIDEO LINK:
https://youtu.be/qcqBsDuyIEo