[ToxicWill]

First post. New to form. https://www.dropbox.com/s/byakvsze48...%2055.mov?dl=0
Recently with gas prices started using eco mode on my 2016 320i
Car only has 56k miles. And at start up car makes this sound that never made before. Any one here have an idea.?

[Orion4]

It sound like possible the tension pulley bearings. Sounded like it went a way after you rev'd the engine. Is that so? Does it only occur just after start?

[ToxicWill]

Correct, after I turn the car on, it makes that noise, and it goes away when I rev the engine. Also when I come to a complete stop and it does that “stop-start”

[dmaxdmax]

You can use a stethoscope or a hose 'as' a stethoscope to isolate the location. Get someone else to start it and listen. Careful around moving things like pulleys.

Although the location may not be exact, I hope it gets you close enough to figure out.

[Wires]

It's definitely a bearing issue. Most likely the tensioner.

[ToxicWill]

Update on 2016 320i
Took the car in and had it diagnose

Performed vehicle test, found fault code: 118401 mixture
control: fuel mixture too lean, large deviation. Performed
test plan, measured crankcase pressure, found pressure
is out of spec. Found internal crankcase pressure control
valve defective

Among other issues found during their inspection

[dmaxdmax]

...so my guess is that means you could use a $30 pcv diaphragm from Ebay (I think).

I believe bmw's fix is to replace the entire valve cover (with new diaphragm).