M271 serpentine belt

[zenman63]

Just looking at the wives car as it make a rattling noise in drive when cold.

All is sweet until you put it in drive and then the serpentine belt seems to vibrate.
Looking down at the tensioner its humming and vibrating and seems to be where the noise is coming from.

Is it common? the belt does seem tight enough but why would it do this?

 

[jaymanek]

It could be any of the pulleys causing this... water pump, tensioner pulley, idler etc...

Need to remove the belt and have a feel of all the pulleys.
Get it checked before you get stuck!

 

[zenman63]

Hmm ok I can whip the belt of easy enough, what am I looking for?

 

[jaymanek]

play in pulley or any rough bearings... Otherwise it will be the tensioner not doing its job,..

 

[zenman63]

Slow motion of the tensioner moving:

https://www.youtube.com/watch?v=qXRwaaI4rJQ



https://www.youtube.com/watch?v=IgH3XAiKAao

And a short vid of what it sounds like in drive.

 

[BlackC55]

Alternator pulley is seized. Common problem.

 

[zenman63]

Ok Thanks, i will take it apart now, will it need a new one?

 

[zenman63]

New pulley on the way, I googled it and yes like you say its common, thanks for you help on this.

 

[BlackC55]

You will need a tool to remove it.

 

[zenman63]

All done and 100% fixed, I just had to buy a long torx bit and borrow form MB service the spline tool, £34 for the pulley.
Thanks Olly.