ID this noise
 

Happens at engine shut-off. Sounds like a kitten sneeze... been happening since I bought this thing. Tried to post a video of it but icloud is not cooperating... M54.

It's likely the vacuum in the crankcase being leaked back through the CCV. Or remaining manifold vacuum leaking by the throttle. Or combination.

Post the video on YouTube shorts. Interesting.

Duh, forgot about utube... https://youtube.com/shorts/S1advYqhKkw?feature=share

Should be available shortly.

Wow, that's loud. Do you have a mechanic stethoscope? Brake booster, vacuum reservoir, or oil separator valve. Remove the oil cap at idle. Does it have a large vacuum suction on it?

I have that too but only after it’s warmed up, I think. Interesting

I'll check that, thanks.

Yep, definitely some strong suction. Is that normal? It's an M54.

Is vacuum is this bad? Excess vacuum is symptom of a bad CCV valve. Has yours ever been replaced? Is it using excess oil?

Mine used to make that noise every time I shut down. It hasn't happened since I did the CCV delete.