Friends:

I'm getting ready to install new serpentine belt on the 300TE. The MB shop manual speaks about some graduations on the tensioner, and to tighten it to pretty much the last notch. My tensioner does not have the graduations, only a 'triangle' marking with no graduations. I had the existing belt off a couple of weeks ago and tightened the tensioner fully (pointer all the way to the edge of the 'triangle' when reinstalling ... the belt seemed soooo tight - I could barely deflect it, I'm comparing it to the normal 1/2" up or down I've always used on my other cars - that I loosened up the tensioner to about half way.

What's the best/right way to adjust tensioner which does not have the graduations????

Many many thanks -

Brian
89 300TE 157,xxx
84 733i 5speed 138,xxx

That's the way I adjusted mine recently, and so far, so good. That was what the Haynes' manual indicated to do.

Good luck,

Whoa... Something ain't right. Either the belt is not properly routed (possible, but not likely), or your tensioner pointer is not properly positioned. Here's what to do. Loosen the big retainer bolt in the center of the tensioner (19mm). Back off the tensioner adjusting bolt (the long one behind the PS pump) Take a look at the little pointer and press down on it and set it to the edge of the big end of the triange on the tensioner. Recheck the belt routing and make sure that's OK. Start cranking down on the tensioner bolt until the pointer moves the to far end of the triangle (the little end). Retorque the big retainer bolt and you should be OK. The pointer is easily moved and I suspect your pointer is not properly positioned. If it can't be adjusted properly this way, then something else is amiss. Good Luck and Merry Christmas...BTW, there are two versions of the tensioner. one with markings and one without. Your version has the triangle (without). Same rule applies for both..