Help! - Need help to identify a sound

[Hubu]

Hi,

I’ve gotten into a chirping sound in my N47 F30 316D approximately 2 months ago. It can be heard when the car is warm and idling

In the early phase of troubleshooting I was almost certain that the sound was coming from a dry bearing from one of the pulleys.

Parts I've replaced since then: the crankshaft pulley (also because of engine vibrations), belt tensioner, the belt itself, ac-compressor pulley, alternator pulley, and finally the whole alternator - none of these have unveiled the culprit.

This sound comes after a while of driving, and when engine is shut down after driving as little as 1-2 kilometres.

The sound seem to disappear when I put proper load on the AC (when turning up to max).

I will put a link to a video of how it sounds when the engine is shutdown (you can also slightly hear it when it runs).

Link: Chirping/squeaking sound - YouTube (https://www.youtube.com/shorts/fE49wug6meM)

Thanks.

[328 Power 04]

I just listened to it, that is so strange. I'm very familiar with F30 N47 and would have done some of the same parts swaps. Did you rev it a little before shut down?

If it does it constantly at one point, can you use a mechanic's stethoscope (or a large screw driver up to the ear) to get closer to the source.

[Hubu]

I will have to make myself a DIY stethoscope and give it a go - I think it's the only way to find the source of this sound.

Thanks for help!