https://www.reddit.com/r/G37/s/Ze3rHoFJuD

Pulleys and tensioner have been replaced and serpentine belt too. Same thing for fan assembly.

 

Remove the belt and try spinning each pulley by hand- ALL of them: idlers, tensioner, AC, alternator, and PS. They should spin smooth like silk without any "roughness" or play (wobble). Even "new" components can fail.

Sounds like a bearing somewhere running dry and if I were to venture a guess, I'd say alternator as that spins at a faster RPM.

Maybe others will chime in with thoughts/ advice.

 

Eureka! It was one of the grooved pulleys! Thank you for the help! Crazy the amount of noise it was making. There was not a lot of “stuckness” when I was spinning it but hey I’m not complaining. I swapped it out with the old one while I look to see if there was a warranty for the one that failed lol

 

Good news. Lucky you kept the old one as a spare.