Belt Tensioner

[Smokiesman]

Looks like I may have sold My 300 E! But I have this very bad squealing from the belt. I want the car right when the fella picks it up so I bought a new fan belt and took it down to my local small repair shop to have installed. He called me and said the tensioner was bad he said he could not tighten belt but also admitted he had never seen one "quite like it"! Could someone here explain how the adjuster works ? Is this spring or mech tension?? New tensioner from stealer is $175 so I want to be sure he is doing it right before I blow $175 clams !


Smokie

[psfred]

The tensioner was a very clever design that didn't quite work as planned. It uses the same rubber material as the rear suspension links as the "spring", providing great vibration damping and quiet operation.

Unfortunately, as you have discovered, the rubber dies with age and use, with the result that it will no longer generate tension on the belt no matter what you do with the tensioning screw.

Bite the bullet and replace it. $175 is right in line (see FastLane). Only necessary every 15 years or 200,000 miles.....

Chances are the rear links are goofy too.

Peter

[softconsult]

This is quite common. You will have to replace the tensioner and you really should replace the tensioner shock absorber wihile you are in there, 30 bucks.


Not your problem. Unfortunately, perhaps, depending on the buyers knowledge of MB, this is the first of many replacements that will come up around this mileage point. They will include, radiator broken neck, alternator, A/C compressor and related goodies $ 1300, muffler, water pump, differential pinion seal, front flex disk, motor mounts, and anything rubber, like all bushings from differential, to control arms, to subframe mounts.

These are great cars, I own two, but not cheap or for the faint of heart as they go from say 100K to 150K.

Steve

[softconsult]

Sorry for the double post, and realize you are out where there are probably no
MB shops. If your mechanic isn't familiar with how to R&R the tensioner, then
somehow you had better seek out the instructions. You do not want to screw this up.

Steve

[haasman]

Be advised also that the belt tensioner units can twist inside their housing. Upon visual inspection looks fine, but some times are not.

This just happened with my 190e 2.6. The belt wouldn't adjust properly but after removing the tensioner it looked fine.

I remember reading how the inner section can twist within the rubber so I put it into a vise and tried twisitng it, sure enough it turned. The isolating rubber between the inner and outer sections didn't appear to be crached or ripped.

I replaced the unit and got the proper adjustment right away.

Haasman

[Smokiesman]

I bit the bullet and ordered a new tensioner and rod! Europarts had a very good price !
$100.68 for tensioner and $9.50 for a new rod! Should be here this wk ! got a guy to install for me! Sure looks like a bugger!!! I hope the new owner enjoys his squeal free car!


Smokie