Thanks, I will look for the tensioner by the alternator in the morning. I will also check chiltons in addition to my MB manuals. Any other tips on changing the tensioner would be really appreciated. I noticed in an old post from Steve the moderator that these tensionere, even when changed and new, can have a problem holding oil (my memory, probably not acurate or as he said it) and they can make a noise. Maybe the tensioner has gone south for some reason. I do have 20w-50 oil in there now but it is still warm here, like 60 to 70 farenheit. There was some Castro 5w-30 synthetic in there about 600 miles ago briefly. I cant believe this would matter...my head really is exploding. I have gone from years and years of peace with this car, to a relatively small period aggravation, to a small period of peace, and now back to yet another mystery.