belt tensioner 300e 2.8 M104

[radunegru]

I suspect a belt tensioner problem, because of the noise in the water pump area. Also when the car is in drive I can hear a rattle noise towards the front of the engine that is increasing in intensity when the a/c is on.
What is your opinion?
Thanks

[deanyel]

Get a cheap stethoscope and see if you can tell where it's coming from. They are quite good at isolating the noise. But watch out for the belt.

[Arthur Dalton]

Common belt tensioner shock bushings.
Hold screwdriver blade at bushing and apply tension by twisting blade to tighten bushing mount to verify..
...may also be comp. clutch rattle.

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1D00YU6RY1ID1CTLJN&year=1993&make=MB&model=300-E-003&category=G&part=Acc.+Belt+Tension+Damper

[hudsmore]

I agree. dollars to doughnuts its the top bushing on the little shock absorber on the belt tensioner. It attaches right behind the thermostat. A bit of a job to get out as the fan, three pulleys and the tensioner has to come out to get to it. I know as I just did this repair 2 weeks ago on my 300sl. (104). If you need more info let me know and I'll walk you through it. You'll need a torque wrench, something to hold the pulleys (strap wrench works) and some high-temp sealer for the one "wet" hole that you need to extract a bolt from. I couldn't be bothered to chase down a bushing so I just replaced the whole shock (accessory belt tension damper) 31.94 @ importpartsonline.com

[Arthur Dalton]

...there is an easy, low cost fix if the shock is rattling back and forth on the top bushing pin. [ which is common].
You can take the one lone mounting bolt that goes through the
the shock top eyelet and sandwich an "O" ring between the
shock eye and the washer. That takes up the side play [which
is the Rattle] dimension of the shock. The bushing itself
is still good. it is just sloppy on the side and this shimming works fine and last long. [And gets rid of the Rattle !! }
What actually has happened is the bushing eyelet glue has dried up and the shock is sliding back and forth on the bushing. The sandwiched O ring stops the sideway movement.

[radunegru]

Thanks for your prompt imput guys but I am afraid it is not the little strut or bushings. It seams to be very tight. I think is the tensioner because the belt is kind of loose and I can't make it tight using the tensioner adjuster.
Now sience the belt is kind of old maybe 60k I am going to change the belt and the tensioner.What other thinks shoud I pay attention to while I am there?