Another Chirping Sound Question

[JRSR90S]

I just completed a 1500 mile drive from Florida to Massachusetts in my 2012 X5 3.5 that has 130,000 miles on the clock. I spread it out to three days and two overnights with legs of approximately 500 miles each. Towards the end of each leg the car developed a high pitch chirping sound that appeared to come from the front of the engine. The following observations were made:
1. The noise started towards the end of each leg and not at start up or after a cool down, an overnight or extended rest. 2. The chirping does not occur under a load (accelerating) or going up-hill. It would come on during descents, at rest idling or on the flats without the gas on.
3. It is difficult to determine where the sound is coming from but clearly from the front of the engine. 4. AC on/off makes no difference. 5. It was a very hot drive with the average temperature in the mid 90s F. There was one rain shower during which the chirping persisted. 6. I spoke with a tech from the local BMW dealership but he needed to hear the sound and unfortunately it is not available on demand. 7. The fan belt and pulley were replaced approximately one year or 6K miles ago. 8. Since my arrival I have been driving around locally without any noise.

Those are the key points. Any ideas are appreciated. Thanks.

[Daytonawim]

Can you make a video of the sound?

I would think something with vacuüm. On the valve cover is an rond think that could leak.
Also de tube on the left side from the cover to the inlet pipe, that like to break.

[lacheesy101]

Hi JRSR90S, does the sound make a racket like this on a cold start?

https://youtube.com/shorts/BEgzfLqgoK4?feature=shared

Been doing a little searching around and it sounds like a pulley and serpentine belt replacement.

[TTV8M]

what about something with the suspension? or a wheel bearing?

Yeh i was initially thinking either the AC belt, or the serpentine belt (mine are separate on the S63 motor).