Scratching sound at idle from engine bay

[jumbotron]

Hi everyone,
New to me M3 started making this scratching sound coming from the engine bay. From what I can tell seems to be coming from alternator area. Could it be due to alternator/starter/belts? I will check if the sound varies with RPM

https://www.youtube.com/watch?v=CWSAn2cGlYM

[fourmula1]

Looked like it was timed up perfectly with something on the belt?

[Casa de Mesa]

Sounds like a pulley to me.

[maupineda]

^^^ same here

[lemoose]

ha no way mine was making this same noise earlier this week even though I just got both alt pulleys and tensioner replaced the week before. seems to have gone away on its own and was maybe due to cold weather- if you're not sure when the last time those were done Id start there

[Arinb12]

I got oil all over my belts and pulleys recently when doing vanos stuff and it made this sound till I cleaned it all off with brake cleaner...

[jumbotron]

Thanks everyone I'll start there