Fan belt slipping

[BWDuncan]

Hi there,

I've just bought a 13 year old C220 Diesel with 130k miles and no service history. Apart from a squeak from the rear left shock absorber (it has a towbar!) it's been running silently for about 400 miles. Now I'm starting to hear things...

The page in the MB manual which describes the fan belt circuit is well-thumbed! If the previous owner has replaced the belt or tightened the tensioner, is there anything I can do to stop it squealing? Is the belt supposed to be tensioned automagically?

As soon as the Haynes manual arrives I'm replacing the black syrup with oil... Is this going to be an easy car to DIY?

Thanks,
Bruce

 

[grober]

Its probably the bearing in the poly V belt tensioner pulley. Its tensioned automatically. Replacement is the answer. MAKE SURE ITS NOT JUST ALTERNATOR SQUEAL which will be more noticeable just after starting the car and nothing to worry about. It may indicate your battery is on its last legs tho. Best way to test it is to remove the V BELT and check each pulley individually for roughness. Lots of posts on here about this if you do a search.

 

[BWDuncan]

Its probably the bearing in the poly V belt tensioner pulley. Its tensioned automatically. Replacement is the answer. MAKE SURE ITS NOT JUST ALTERNATOR SQUEAL which will be more noticeable just after starting the car and nothing to worry about. It may indicate your battery is on its last legs tho. Best way to test it is to remove the V BELT and check each pulley individually for roughness. Lots of posts on here about this if you do a search.

After a bit of searching I'm starting to doubt my initial diagnosis. The squeal is a constant pitch at all temperatures and engine speeds. Is this more likely to be a bearing somewhere?

Bruce

 

[BlackC55]

The alternator has a freewheeling pulley. Have a look at this.

 

[BWDuncan]

Go team!

It's the alternator. I ran it with the fan belt off and the squeal was gone. Turning the alternator by hand gave a very audible squeak. I turned the alternator backwards a few turns and reinstalled the fan belt. The squealing has stopped but clearly it will reappear in time for the MOT . I suppose I should be searching the forums to find where people buy parts...

Also, what's a freewheeling pulley?

Thanks very much!
Bruce

 

[lynall]

Also, what's a freewheeling pulley? Expensive

Guessing its what it says, no charge required equal no drive, may be electric like the vw ones similiar to a/c compressor clutch


Lynall