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2010 E350 4Matic 55,000 squeaking after start

6K views 8 replies 6 participants last post by  rgtsc01 
#1 ·


Two thousand miles ago had complete belt and pulley replacement by German Autowerkstatt here in San Diego for $588. Mechanic said one pulley was bad.

Car exhibited pronounced squeaking after cold start. See my video at:



I sprayed belt conditioner on the belt after belt change, but squeaking persists.

Suspect belt tensioner?
 
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#3 ·
Squeaking



Two thousand miles ago had complete belt and pulley replacement by German Autowerkstatt here in San Diego for $588. Mechanic said one pulley was bad.

Car exhibited pronounced squeaking after cold start. See my video at:

https://www.youtube.com/watch?v=I5OIHr3bbjQ

I sprayed belt conditioner on the belt after belt change, but squeaking persists.

Suspect belt tensioner?
It definitely sounds like something is slipping to me, if you replaced the pull and belt, tensioner would be next for me however.....my e350 jsut had its belt replaced at 97k and was still running the original pulley, tensioner, belt etc and service department said only belt needed replaced, tensioner was fine. Id just skip the guessing and have a dealer look at it. Worth the diagnostic fee not to chase a problem, that way you can have someone on the hook if they dont fix it.
 
#6 ·
Well you drove it for 2k after service. So it could be just bad luck. I always inspect work done by Dealer or independent. It could be alternator or some other component. I had to remove belt and spin them and found alternator bearings bad. I would take it back to who did repair and have them diagnosis it. Even it the tensioner went bad doesn't mean the F'ed you. Nobody has a crystal ball. John
 
#7 ·
The tensioner and pulleys were known to go bad in previous years. On the other hand my 2011 seemed like it had the original belt when I changed it at 98k. Either one of the other pulleys went bad as mentioned or it's possible they left out a washer when replacing one of the pulleys so that it's now misaligned. If everything is properly set up, it shouldn't squeal and you shouldn't need to use belt dressing.
 
#8 ·
You should try to find the pulley that's responsible for the noise (it definitely sounds like a tension or pulley issue).

Grab a spray bottle, fill it with water, and turn the nozzle to the precise jet stream and give each pulley a squirt going around. When the sound stops, you've found the pulley. Then you need to check the pulley for obvious damage, and test the belt tension with a Krikit device.

If they didn't replace the tensioner when they did the belt and pulleys, there's a chance that it just finally gave out with age.

As Lawndart also pointed out, it could be the bearings of an accessory, like the alternator; though that still sounds like classic belt squeal to me.

You mentioned it does this at cold start? When the car is warmed up, does the sound disappear? When the belt is cold, it is more rigid, but after warming up, the belt softens up reducing the slipping potential you may experience with a rigid, cold belt, especially under load at initial startup from the alternator.
 
#9 ·
Thanks for your response.

This mechanic did a routine oil change at 52,000 miles and caused a major oil problem when the filter had a bad seal. Car was leaking oil and he failed to diagnose the seal problem a second time (flat-bedded TWICE at his expense) where more oil got out. This angered me to such an extent I asked him to pay for the cleanup in my garage and driveway. Asking him to take responsibility of this made him very angry. I'm wondering if he is trying to recoup the flatbed costs by nickle and diming me. Maybe this squeaking is a pulley missing a backing washer so it doesn't spin straight.

I'm going to try a different German car mechanic (there's a few north of me in Oceanside) and ask him to look for "fishy" stuff. Car only has 55,000 miles so I can't really buy into the idea of the belt tensioner being bad.
 
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