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1999 ML320 (SOLD), 2011 BMW X5
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157 Posts
Discussion Starter #1
In the last 1000 miles I have replaced the serpentine belt, the tensioner and the idler pulley. All were purchased from Autohaus.

Yesterday upon startup, I experienced a squeal that times with the belt rotation. (squik-squik-squik-squik, real rapid, in time with each turn of the belt). It is not real loud but can be heard when standing next to the car with the hood closed.

It goes away after a few miles of driving. Any guesses/ideas what it could be? Hopefully an easy fix. The harmonic balancer was replaced under warranty but it has been many miles and years ago.
 

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2001 ml 320
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19 Posts
Maybie alternator bearings or other accessory brg. ex. compressor clutch brg.
take off the belt and manually turn everything and see if any noises from brgs. also double check all pulleys are clean/alligned paying close attention to anything that may not have "gone together" well when the parts were replaced..
 

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1999 ML320
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453 Posts
Also when you have the belt off check for any debris on the pulleys and clean the pulley grooves with brush to make sure belt it seated all the way in to prevent uneven tension during rotation and extensive tensioner (jumping) movement.
Usually squeal means not enough tension, does the new tensioner spring feels as tight as on the old one? I just replaced mine with oem couple weeks ago.
Bernard
 

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1999 ML320 (SOLD), 2011 BMW X5
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157 Posts
Discussion Starter #4 (Edited)
Will try the two things above, thanks.

The belt, tensioner and pulley have about 1000 miles on them, went in without a hitch, were all OEM, and improved the driving feel of the car instantly after installation. Is it within normal to experience issues after 1k miles?

One thing that MAY be a factor is temperature... this is really the first set of cold temps we have had this season (not very cold, but around freezing). What might that indicate?
 

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'00 w163 55 amg (sold) '02 w208 55 amg '03 w163 350 inspiration
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711 Posts
hello kck. would love to know your results/update. I too have similar story. idler pulley, tensioner, & new belt in May of last year (I believe) by my indy. due to temps here as well I've heard this belt off/on for about 2.5 weeks now. tonight, it once again shredded just 2 miles from my house. manhandled her to a parking lot & on a flatbed to my indy's an hour after that. My indy uses stock parts & provided 12 mo/12k warranty on work so I'm dying to know what (re)caused this problem.
 

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Purple Moderator
99 ML430, 00 ML320, 05 E500 4matic Wagon
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22,129 Posts
I am not sure your belt shredded due to temps. It has been below 0º here since late
Thursday and my rather high mileage belt is just fine.
A pulley on one of the accessories could have failed and taken the belt out.

Recently saw a DIY job for an idler pulley that was not torqued correctly and it backed
off its mount and took the belt with it.
Lots of variables in the system. I can't 100% rule out temp as the cause, but if it was
the materials were defective or something in the replacement of the three parts you
mentioned may have let loose. It may have been human error on the repair or a failed
part.
The system is designed to last for years at a time in climates where winter temps are
single digits for months. The failure rate in states like mine or MN is not high on well
maintained vehicles. I am not saying your vehicle is not well maintained, just something
unexpected happened. You will know on Monday. Sorry it left you stranded.
 

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1999 ML320 (SOLD), 2011 BMW X5
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157 Posts
Discussion Starter #7
hello kck. would love to know your results/update. I too have similar story. idler pulley, tensioner, & new belt in May of last year (I believe) by my indy. due to temps here as well I've heard this belt off/on for about 2.5 weeks now. tonight, it once again shredded just 2 miles from my house. manhandled her to a parking lot & on a flatbed to my indy's an hour after that. My indy uses stock parts & provided 12 mo/12k warranty on work so I'm dying to know what (re)caused this problem.
What Noodles said is what you should look into. As for my case, it kept squeaking until I traded the car in about a week after that post above. It only squeaked on startup and that only for a few minutes at most.
 
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