C63 M156 Engine noise

[GillyC63]

Evening,
Started the car this morning, 2012 C63, 48k to hear this awful noise:


Any ideas what it could be? Seems to be coming from where the pulleys are located. Or is it something more sinister? No EML & car running fine apart from the noise.
Obviously won't be using it until I can speak to my local indy.
Thanks in advance for any replies.

 

[daveenty]

I'd hazard a guess at an alternator bearing, possibly even just a bearing on a belt tensioner.

A decent local garage should theoretically be able to sort this out for hopefully not much money.

 

[GordonTarling]

Definitely one of the pulley bearings. When my serpentine belt was chewed up last year, my garage replaced the tensioner and three idler pulleys, so get them all checked. I'm also told that the water pump bearings are prone to wear/failure, so check that as well.

 

[Petrol Pete]

it doesn't take much to take the belt off and wiggle all the pulleys, best done from below on a ramp/lift , taking off the lower engine covers takes the longest time !...and remembering which path the serpentine belt takes when putting it back on. Any garage could check this for an hours labour charge.

 

[GillyC63]

Quick update: Was indeed a failing pulley. Warranty company picking up the bill with a nominal payment from me for the new belt. Thanks for the help guys, much appreciated.