Squealing / squeaky belt when cold - fixed!

[sjcsl55]

I had a terrible squealing sound from the supercharge belt that lasted for the first 5 minutes or so until the engine warmed up. Found a fix! While the engine is running, using an aerosol can of silicone spray (with the red tube extension attached to the nozzle), lightly spray the v-grove side of the belt. For me, the squeal instantly went away. I gave it a few more light sprays for good measure. Yay!

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[kamilclk430]

Originally Posted by sjcsl55

I had a terrible squealing sound from the supercharge belt that lasted for the first 5 minutes or so until the engine warmed up.

Found a fix! While the engine is running, using an aerosol can of silicone spray (with the red tube extension attached to the nozzle), lightly spray the v-grove side of the belt. For me, the squeal instantly went away.

I gave it a few more light sprays for good measure. Yay!

Thanks I have the same problem on my 04 55. So it is AEROSOL SILICONE SPRAY?? That is it huh?

[sjcsl55]

Well, the can just says spray silicone lubricant. I might have posted too soon... I think the fix might have only been temporarily as the squeal, while not as bad, was back the next morning.

For the real fix, I think I need new belts and the pulleys need cleaning prior to installing the new belts. I read somewhere that after taking the old belts off, to clean the pulley surfaces with a scotchbrite pad, degreaser / brake cleaner to make sure no contaminants are on the pulley.

I've been searching, but I cannot find a DIY on belt replacement... waiting for my service manual to arrive.

[EXECMALIBU]

This is the first that I am hearing from others about the sqeal in their SL55s!

My SL55 had the same very loud and HORRENDOUS belt squeal and several MB dealers were unable to fix the problem! They replaced the belts,pulley, idlers etc and the squeal kept coming back. After a while it got much worse and would last longer. It would SQEEEEEK AND SQEEEEEAL in the mornings up to 5 minutes or 5 miles. This was both very annoying and embarrasing in a $135,000 Mercedes

There was absolutely not doubt it was from the belts as opposed to a bad bearing in the idler or pulley etc, because as you discovered the second you spray the belt with lubricant the noise instantly disappears! But the dealers were totally baffled and unable to fix the squeal after numerous attempts.

The silicon spray works great but only for a few days. I kept the can in the trunk.
I hope that you have better LUCK finding the problem or just keep a can of silicon spray handy!

[sjcsl55]

Interesting... I know what you mean, however... coming home my neighbors wanted to check out my new ride and as soon as I started it it squealed like an injured pig!

I'm glad you posted, because my belts look just fine and I was going to try replacing them.

I'm wondering if there is an "alignment" problem... i.e. if all the pulleys are plumb with each other and on the same vertical plane. There's got to be a way to fix... I can live with the "chirp" of the SC engaging, but the squeal during warmup is driving me nuts!

[EXECMALIBU]

The belts being out of alignment was something that I definitely suspected and I even tried (with no success) to discuss this with the numerous MB techs and shop foremen.

Obviously a laymen who drives a Mercedes knows nothing about things mechanical and they blew my ideas off! They kept throwing parts at it and even tried to order the wrong size belt (smaller) from a C class. I told them this was a Mickey Mouse band aid attempt to fix the problem and would never work..

Of coarse when the C class belt finally arrived from Germany it would not fit....What a surprise!

The MB dealer finally admitted that they had tried everything and had no other ideas and needed more time (up to a month) to try and figure out what was causing the squeal.

That was the last time I saw my SL55...

[OC_AMG]

Replacing the belts on an SL55 is too easy to discribe. 17mm socket and a small extension for the non supercharger belt. You could have both of them off in about a minute. Upper Auto Tension is very visible for the Supercharger Belt. The longer one is a bit tougher to find. Its just to the right of the Harmonic Balancer and above looking toward the engine.

Both belts are available for about $ 30.00 Ea. I would also check the idler pulleys. I just replaced my dual idler unit that supports both belts myself.
That part is a little bit over $ 400.00 list. Not too keen on spraying anything on these belts. If they are in good shape and all the other components are worrking and inline it should be very quiet. Just the noise of the SuperCharger Clutch at idle.

[charles pearson]

I had the same problem in my CL55, turned out that I had the wrong size belt for my Renntech pulley. I too tried spraying silicone on the belt, but just like WD-40 it's just a quick and short lived fix. The Funny thing is, it only did it in the cold weather.

[Grk-AMG]

It's very annoying and very embarassing, I have the same problem too hopefully the dealer can fix it tomorrow, did anybody get there's fixed who had this problem?

[allenjdmb]

It was really noisy when cold, I mentioned it on a warranty claim ticket, and they replaced the belt at NC. When it started making just a light chirp at startup, I mentioned it again,at another dealer. They sprayed it, suggested belt replacement (?!). This was only after about 3k miles on the other belt...I'm guessing they see a bunch of it and don't even look now. I can live with the very slight chirp for a minute or so....

[bfnnrgn]

It's probably pulley alignment. I had a stock SL55 that was quiet as a mouse. I then put in a pulley along with a new larger belt to accomodate it. All was fine until about 1k miles later it started to squeak when I started it. Eventually went away after a few minutes but the more miles I put on it the longer it would squeak until it just squeaked all the time. I took the belt off and flipped it around and no more squeak, at least for a while. It came back. New belt and the same thing after a while. The new pulley was out of alignment slightly and caused wear on one side of the belt.