Belt squeal after pulley change M113K

[SL03WLY]

Hello All,

I've recently had all my pulleys changed, including a new clutched supercharger pulley.

All was fine on the day of install and test drive. However, next morning I got a really bad squealing noise coming from the belts.

I sprayed a little squirt of WD-40 onto the belt and for a split second the noise stopped

This noise also stops once the car is fully warmed up.

I took off the supercharger belt and the noise was still there. It appears to be coming from the pulley that is mounted onto the belt tensioner.

I took the serpentine belt off and checked all pulleys by hand and no issues appear when spinning or moving laterally. Smooth and no grinding. The tensioner itself moves smoothly when I rotate this

The belt itself, is original but I can't see any cracks or anything else of concern so am baffled. Possibly the belt has stretched? but not sure as it was fine with the old pulleys, which by the way were all shot.

Any suggestions or ideas?

I have arranged at some point to change the tensioner, but in the mean time will replace the belt.

Thanks

 

[johnsco]

I would certainly change the belt.
I would not spray the belt or the pulleys with WD40.
WD40 makes things slip and that is NOT what you want.

 

[350cls]

My pulley bearing used to rattle a little sometimes. I used to get a piece of card place it between bearing and bearing casing and Spay a little when the car has been run. And the spray would stop the rattle more or less straight away. Most bearing pulleys do make a sound especially when the SC clutch engages. I'll try and find the stuff that was recommended to me. Can't think of the name of it right now. Also unsure if this is the issue you may be experiencing.

Graphite lube spray. Can be a help with a rattling pulley bearing. It help me for a while but mine did eventually need replacing. Again unsure if this your issue.

 

[Teego]

Did you change the idler pulley? The one with two pulleys on one shaft. One plastic and one metal

 

[Alps]

change the belt, see how you get on

 

[MrGreedy]

You can use a spray of water to stop the squeal and thus identify the squealing belt. Water then evaporates.

Squealing belt:
Change idlers, belt and tensioners, in the order of oldest to newest cheapest to most expensive. If you can tell what area on the belt run, that might help.

 

[wrdcc01]

Have a look from the side and see if the belt is lined up perfectly straight across all the pullies. Any slight deviation will cause a squeal. Were all the parts genuine MB or could there have been an aftermarket component used which may be slightly taller or shorter?

 

[SL03WLY]

Thanks everyone for your help. Changed the belt and so far so good. Even though the new belt looked worse then the genuine. Will see how it sounds now on cold start. If it squeals will hope changing the tensioner does the trick.

All the pulleys were changed with brand new UPD ones. Hence why I was concerned the following morning with the annoying squeaking. Time will tell, UPD kindly provided me with the bearing part numbers which is handy.

 

[mioba]

Personally would have got gen MB pulleys, replaced the tensioner and belt again MB only

 

[Teego]

Did the new pulleys get new bearings?

 

[SL03WLY]

I hope so, these are the UPD idler pulley kit. 5 piece using the same nachi bearings as in the genuine ones. but all seems well at the moment. Tried again this morning and no squeal. Apparently these are sold by a fella named Shardul in USA. Acid mentioned him to me too as I've seen this name mentioned on various MB forums.

Kit bought from M113k Gold 77mm & 5 piece bundle AMG mercedes E55,CLS55,S55, CL55,G55, | eBay

Comes in Red too - M113k AMG Mercedes Red 77mm supercharger pulley & 3 piece idler kit bundle! | eBay

 

[SL03WLY]

So the squealing belt is back this morning. Though for a very short time this time compared to the old belt. Guess its time for new tensioner then

 

[Teego]

So the squealing belt is back this morning. Though for a very short time this time compared to the old belt. Guess its time for new tensioner then

Is it deffo the belt that's squealing? If so, which one?

 

[SL03WLY]

Is it deffo the belt that's squealing? If so, which one?

It is the auxiliary drive belt not the supercharger that is squealing. It stopped after I changed it but returned on 2nd day and now there is a black mark on the aux tensioner pulley now.

 

[MrGreedy]

As already recommended, I'd get a genuine belt from Merc and try that.

I had a Volvo that was very particular about belt size as well as there being 3 lengths within a few single mm of each other. So for the sake of a few quid I usually go genuine on stuff like this where errors in OE and aftermarket look up and manufacturing are more likely to exist.

 

[SL03WLY]

As already recommended, I'd get a genuine belt from Merc and try that.

I had a Volvo that was very particular about belt size as well as there being 3 lengths within a few single mm of each other. So for the sake of a few quid I usually go genuine on stuff like this where errors in OE and aftermarket look up and manufacturing are more likely to exist.

Yeah that is a fair point. Will try that out at some point but appreciate the advice.

 

[Teego]

It is the auxiliary drive belt not the supercharger that is squealing. It stopped after I changed it but returned on 2nd day and now there is a black mark on the aux tensioner pulley now.

Be good to have a close look at that belt for possible manufacturing defect.
I replaced both belts on my M113K 2 years ago when the idler pulley failed.
After 13000 miles they are fine.
Got them from my local motor factor:
GATES 6PK2448 Micro-V Multi-ribbed belt £17.13 inc VAT
GATES 8PK1289HD Fleetrunner MV belt £29.54 inc VAT

 

[SL03WLY]

so took the belt off again today and noticed on the pulley, melted rubber on the edges of the grooves. Took them off with a toothpick.

I once again checked all pulleys for any play yet can't feel anything.

Any ideas how one can check if puleys are aligned correctly?

Bare in mind this noise goes away from cold start after maybe 2-3 minutes. So don't want to fit the new belt if its going to get shredded quick as its costs £50 for an OE Genuine one.

 

[MrGreedy]

Could the 'melted' rubber be a congealed mess from the WD40 spray picking up old belt dust and the somewhat setting and forming what you have found?
Rather than the belt having actually melted?
No saying it is that. You will know better as you have looked at it, but just a thought?

 

[SL03WLY]

Interesting point there. The WD-40 btw just to be clear D) I didn't drown it in the liquid hahahaa just a light squirt to see at the time if the squeal would to stop. A test.

But will clean it all up, re-fit and see how it goes from there.

Thanks