CLS WINDOW SQUEAK

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The Smudger

Member
Joined
Aug 12, 2016
Messages
42
Location
WILTSHIRE
Car
W211 E320CDI, W208 CLK 320, 260E W124, W219 CLS320
I have a 2006 CLS which developed a 'Shriek' when the passengers side front window was operated. It only seemed to happen on the way down for the first few inches, and seemed much worse when it was hot. I read on another forum that this was usually the beginning of the end for the regulator and that the only cure was to renew it. This seemed a bit drastic to me as the window operation was perfect apart from the noise, no cable graunching, no tight spots, just this ear piercing screeching noise.

With the panel removed and on inspection i could almost 'feel' the noise by putting my hand on the down rails, it felt like a really harsh vibration which manifested itself in a noise. WD40 did seem to reduce the noise, but it came back within a day. A bit of thinking and i found that the noise was actually generated by the small blue and green plastic guide runners (pictured below). I remembered that the noise started after a really hot spell, and on closer inspection the plastic runners had gone very hard, probably due to the excessive heat, and also seemed to have swollen, which made them too tight on the metal guide plates, thereby causing them to 'judder' when operated rather than run smoothly as was intended.

I also read on the other forum that some people seemed to have got away with greasing the runners, but this always seemed to be a temporary fix. So, what was needed was a grease that could withstand high temperature, but would not soften too much and literally drip away. I decided that Copaslip grease was worth a try as it has those qualities. I smeared a little bit on the runners and blue and green guides, and worked the window up and down. The result was instant. The noise went immediately, and the window runners when the window was operated felt very smooth. I felt very confident that this would/will fix the issue. A few days on, and it has been very hot, the window is still very silent and smooth, a good fix i think!

A new regulator would definitely cure the issue as the regulator would of course come with new blue plastic guides, but my 'fix' is a lot lot cheaper and easier, and more satisfying!

Here is a photo of the 'offending' runner, there are 2 of these and both can be lubricated with the door panel off and the water shredder/membrane carefully peeled back. NOT MUCH Copaslip is needed, I just applied a 5p coins size blob on the runner/blue and green plastic parts and when the window is worked up and down it carries the lubricant with it.

I am happy to answer any questions on this subject!

IDixnTt.jpg
 
Last edited:
Had the same on my W219 passenger window and fixed it with some hi-temp silicon on those parts. Did the other three at the same time as I was taking all of the door cards off to fit sound deadening.
 
Hi,
Thanks for posting this, as both my rear windows have screeched real bad in warm weather for years.
Will look at this in the next week or so.
 
Yes mine does this in hot weather. had my indie strip the passenger front and lubricate which is now silent but now the drivers side has started. So looks like its time for the other three to be done. is it easy to get the door cards offas thats the only thing putting me off doing it myself. ?
 

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