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

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

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

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

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

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

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

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

Be sure you install the tensioner rod correctly (don't ask me how or why I know this!)

When you are taking it apart, take careful note of how everything is attached and lined up.

What I did was install the tensioner arm 180 degrees from the way it was supposed to be installed and after 60 miles from home, I lost the belt tension.

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Hey tanks for the update!

Smokie

No one else has mentioned it, so I'll put it in here:

When you replace the tensioner, there is a Y-bracket with three bolt holes. Be aware that the hole at the bottom of the Y, which would be pointing towards the passenger's side, is a wet hole (oil). You need to seal the bracket to the front cover and then put sealant on the dry bolt. Let it all cure overnight before starting the car back up. You can use the orange Permatex and it will be fine, no need to use the MB spec goop.

This is all in the manuals, I just didn't know if you had them or not and this will keep you from an annoying leak after spending all of your time doing a careful job on the tensioner.

Also, you can make your own version of the MB tool for locking the fan clutch by bending an industrial (like you find on coat racks at work) coat hanger to shape. You need something close to 3/16" and these fit well. The manual has a pic of the tool, just copy the bends and you've got the same tool.

HTH,

someguyfromMD