Squeal

[MartynE]

I've noticed a slight squeal coming from the front of the engine on cold start up it disappears when it's warmed up? I would imagine it could be a tensioner pulley? Although I'm no expert, has anyone else experienced any similar noises in the past, car is a W205 C63s

 

[A.J.]

One would imagine it's just a matter of re-tensioning the fam belt

 

[MartynE]

To be honest Andy it doesn't sound like a belt slipping?

 

[mioba]

Tensioners are automatic, The belt needs taking off and the all the pulleys checked, no noise when warm indiacated a pulley is on its way out as the bearings are dry, when warm the little lube left gets circulated.
Its easy enough to change the pulleys, just get original and know the torque.
Change the belt at the time time.
Yoou need to lock off the tensioner when turned with a small screw driver or allen key.
It could also the be tensioner itself which is dead.

All becomes clear with the belt off.

 

[MartynE]

Thanks for your help mate, I'll sort that is it a complete kit I have to buy?

 

[mioba]

No. Whip off the belt (by pulling back the tensioner). Note how the belt threads.
once the belts off spin each pully. they should spin freely and no noise at all. That will identify any pulleys needing a change. So do whats needed,
revser is putting it back.

It can be tight in there and you may need an extension on the tension pulley.

tonnes of vids on youtube. to help you. it helped me.