I see the sprocket on that one bolt, but what is the trick to correct tightening?

Is there a spec to deflection on the upper belt between pulleys?

I just did all the belts, and that one squeals just a bit on start up now that it wore in. 30 miles.

I expected to readjust after a wear in

And you guys are going to set me right on how to

Come on folks, I need to know this before I get my hands dirty again!

I suppose one answer to the spec question might be 'until it stops squealing'

If I remember right, there is a MB tool that actually calculates the deflection when you press on the belt. I think I always just press down with my thumb with fairly good force and looked for something like a half inch deflection.

That could be all wrong but is what I remember. If I can remember I will try to pull up the manual tonight and take a look.

Sorry, that is not very scientific.

Thanks. I am heading out to tighten it up a tad. I will note what sort of deflection I had before and after. My guess is all will be well ( at least eventually) after this event. I couldn't figure out how to make that sprocket help me.

Turns out I did know and operated it correctly. the sprocket adjust is nice engineering. Seems I didn't tighten things down enough. The belt was loose. I did it again and expect it to remain adjusted.

Not sure your engine, but I go by pressing the belt down half an inch.

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).

Can't imagine the belt tension varies by engine. I'm tight now. But deflection would need to be spec'd proportional to force causing it.