Serpentine belt tensioner - help!

[e500.org]

Hello all - gave a local garage my car to change the fan belt and the car has returned with the new fan belt totally loose and the tensioner seems to be broken . MB part, 8 rib and confirmed looks same as old with same p/n. Can't drive the car as belt too loose and no way of tightening it.

Does the tensioner break on the m119 or one of those items which is very unlikely to fail? Tried to tighten the bolt below the tensioner itself either way with no success, no tension just floppy, even if I hold tension then tighten, no success. Anything I'm doing wrong? Car is 1992 and was absolutely perfect before it went in





Earliest the garage can get out to see the car is Monday which leaves me without the 500e over the weekend.

Cheers

Bill

 

[T-500]

This is a common fail item, especially in hot climates.

Changing the fan belt and attempting to tighten it, probably broke the pressed-fit bond between rubber and metal pulley.

Nothing can be done - you must replace the tensioner.

There is a "How-to" article on here, to upgrade to one of the newer, more reliable updated tensioners.

I know that the poster went to a lot of trouble over length of belt, and alignment of pulleys, but I don't know the long term results.

 

[jaymanek]

One time, I managed to break the adjuster. I was trying to tension the belt but the main bolt was tight, I had forgotten to undo it first. This snapped the adjuster arm without much force. Maybe they did something similar?

 

[Klink]

The belt tensioner on the '92 will break at the drop of a hat, and it will bring the hat. If it is on the verge of breaking, it will break as soon as it is disturbed. It is likely not the fault of the garage. Believe it or not, the belt will often outlive the tensioner on a '92...

 

[e500.org]

The belt tensioner on the '92 will break at the drop of a hat, and it will bring the hat. If it is on the verge of breaking, it will break as soon as it is disturbed. It is likely not the fault of the garage. Believe it or not, the belt will often outlive the tensioner on a '92...

That's good to hear (not) - I am too starting to think it's not the garages fault however I do have my doubts and think they may have tried to force the tensioner without loosening the bolt.

Either way it's obviously new tensioner time - anything else worth changing at the same time? I will be replacing it with a part from MB.

 

[T-500]

e500.org

Unfortunately, I don't think it was the fault of the garage - my belt was starting to make noise when up shifting at full throttle- belt loose.

I inspected the belt - it was fine.

As soon as I tried to tighten it - the tensioner gave, and the belt went very slack - that's typical.

 

[alabbasi]

interesting, had the belt come apart on my 02 E55 last Sunday so I replaced it. Last Friday, I did a hard overtake and lost the belt again. This time the idler pulley came apart. At ~ $80, it's not expensive to replace the tensioner.

 

[black-55]

I know this is a bit late to suggest, but I didnt see it mentioned. While at it, check the idler pulley for cracks especially near the bearing, and for bearing noise. Check all other pulleys while you're at it. Idler pulley is known to break apart due to cracks from stress and bearings can seize.

 

[Trae]

My 92' tensioner is at the far right limit. (fourth line).
Should I attempt to tighten it more, or do I run the risk of breaking it.

 

[gsxr]

My 92' tensioner is at the far right limit. (fourth line).
Should I attempt to tighten it more, or do I run the risk of breaking it.

The only valid test is shown in the FSM, which requires removing it and clamping it in a bench vise, and seeing if the metal housing will twist around the rubber bushing. They are a pass/fail item, there really is no "sort of ok" early tensioner. When installing, I prefer to leave it on the loose side (1st or 2nd line max) rather than risk over-stressing the bushing unnecessarily.

How loose is the belt at the 4th line? Don't forget to loosen the pivot bolt before adjusting the tensioning rod, btw!

 

[Trae]

Well. . .lasted four years after tightening, but finally gave up.

Ordered new belt tensioner and plan to replace soon.

Any "how too"write ups or videos would be helpful for the old style, 8 rib belt tensioner.

 

[nocfn]

Well the obvious issue is stuff while you are there Trae. Do you have the SA radiator on the shelf or do you need to replace alternator or VR, Fan clutch? Take time not to butcher the fan shroud upon removal should you decide to do that.

 

[gsxr]

Well. . .lasted four years after tightening, but finally gave up.

Ordered new belt tensioner and plan to replace soon.

Any "how too"write ups or videos would be helpful for the old style, 8 rib belt tensioner.

Trae, did you order aftermarket or new OE? Take note of the location & position of the washer behind the tensioner BEFORE you remove the mounting bolt. And per my previous post, I'd leave it slightly on the loose side to avoid over-stressing the rubber bushing.

Best solution IMO is upgrading to the late-style spring tensioner, but that's a lot of work, and if your early timing cover doesn't have the mounting boss it's unpossible (without replacing the timing cover, which brings me back to "unpossible").

 

[Trae]

Ordered OE from Gainesville Mercedes.

Think I will take the easier route of installing old style instead of attempting the unpossible.