My 95 E320 wagon has a simple spring loaded tensioner. I searched for an hour or two for the clamp bolt and adjuster and there is none. Then somewhere on this site I saw mention of the spring loaded type tensioner on later models. I just put a (13mm?) socket on the pulley bolt and pulled the ratchet clockwise . The tensioner mover and and all the tension was off the belt. It was almost too easy. Perhaps yours is the same?

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Tim Benner

00 ML320 170K
95 E320 wgn 160K