New (to me) 2010 135i M-Sport Convertible Engine Sound

[Raestin]

Hey everyone!

This is my first post here on the boards. My wife and I just got a 2010 135i and it's making a very loud noise in the engine bay. I was told that it was a noisy bearing in the alternator, but it's very loud, and seems to be causing some sort of harmonic vibration in the engine bay. I'm not getting ANY codes or warning lights, so I'm stumped. I can replace the alternator myself if that's the cause, but I'd rather not waste the money if that's not the issue. I've posted a link to the video with the sounds. Any help would be appreciated.

https://www.dropbox.com/s/qlegymillj...33520.mp4?dl=0


Thanks!

Brian


** EDIT: Well, the red battery light came on yesterday, so I guess that confirms the alternator. I'll be ordering it tomorrow and installing it this weekend. I'll be sure to post with results.