guessing here but i'd say the shop set the belt tensioner too tight. good luck, chuck.

Thanks!

Thanks!

I started the car and I do believe the sound is coming from the tensioner (or pulley) located above the alternator on the passenger side - that may just be a pulley and not the tensioner, because I do not see where adjustments can be made there. it looks like the tensioner may be below the water pump? I hope not, it would be terrible to have to remove all of this again. It was a pretty time consuming job. Our mechanic charged $200 labor.

It definitely was not making the noise before the mechanic installed the water pump. The belt does not seem too tight or too loose. Maybe it is a coincidence that the bearings have went out in it at the same time the belt was replaced?

How old is the tensioner and the belt?

__________________
'89 260e (212K Mi.), '92 400e (208K Mi.), '92 400e (not a misprint) (146K Mi.), '95 C220, '81 240D--Sold

86560SEL, it may be a failing fan bearing bracket that is making the noise. I had that experience after a mechanic replaced the water pump in our 1991 300CE, due to the drive belt being over-tightened. If you are not a DIY'er replacing the fan bearing bracket requires stripping down the front of the engine ... quite expensive if you're paying a mechanic. If that's the problem buy a reconditioned fan bearing bracket from a MB dealer, rather than some cheap knock-off brand.

I would take the car back to the mechanic and get an explanation for the noise. There are many things that could be making the noise. In any case you would expect the noise existed when the mechanic finished replacing the water pump, and didn't suddenly appear right after you got your car back.

__________________
Fred Hoelzle

Not sure about the tensioner, but the belt is brand new.

Yeah, it didn't make a peep before that. We had the pump replaced because it was leaking water. We have already spent over $400 in getting the water pump replaced.

We will see. Thanks!

This is one of the reasons why I didn't install customer parts when I had a shop. The last person to touch the car is held liable for anything that fails later, even if they did nothing wrong.

Does this have an automatic or manual tensioner? A bearing starting to fail can be made louder my adding tension.

At this point we don't know what is making noise and can't reliably diagnose remotely.

My mechanic is going to look at it on Wednesday. He has a garage behind his house and he will sometimes get the parts, or he will let the customers bring them, as they are normally parts he would get anyway. I spoke to him about it at length and he said this car has an automatic tensioner and he did say that with the new belt installation that he added tension to it, but he said a little more, not much. It could be that, but it sounds to me like it is the pulley above the alternator, but I could be wrong.

Thanks.