Don,

I believe you have the arrangement with the alternator attached to a special bolt that goes through the support bracket. You tighten the belt by turning a nut like feature on the bracket that the bolt is threaded into.

There was a recent thread on this subject from someone who still had grease under their fingernails from doing the job. If you can find that, you will be better served than by my recollection. But here it is anyway.

The mount is arranged so the alternator rotates about one of the fasteners, and the other one slides in a slot to lock the assembly when you have adjusted the tension on the belt. I believe the sliding one is connected to the adjusting bolt. There may be another bolt somewhere, but I don't think so. It would also have to be able to slide and I do not recall two such devices.

You have to loosen both of these sets of fasteners (bolts with washers and nuts, all 17mm or 19mm, I believe) to adjust the belt tightening feature all the way in the loosening direction. Take the belt off at this point, and remove the two fasteners. Unplug the wires going to the alternator, and I believe the alternator is yours to take away. It is not that easy as I recall, just because nothing ever is. I remember the adjusting bolt being pretty tightly captured and deforming my bracket somewhat by getting things out of sequence. Once it is free of the adjusting nut though, you can just spring it out of the recess it sits in (the hole in the bracket that is not threaded will catch the end of the bolt so it won't slide out from its position of being aligned with that hole. It has to be able to come forward to get that locking bolt arrangement out. You will see what I am talking about when you get going). It is a half hour job, even with some special man made challenges to get the old one out, and about the same to get the new one in.

I recall a spacer piece, like a section of tube that goes over one of the bolts. It can get glued in place by dirt and grime, and then come out when you are jerking the alternator around to get it out, and not looking for parts to fall off the bottom. Not a good feeling when you go to put things back and realize a part is missing and you know you do not know where it is. I found it behind a tire, where it rolled.

Installation, believe it or not is easier than taking one out. Partly because by now you really know how the parts go together, and because you understand the sequence of how to get them to fit. All stuff you tend forget after a few years......

Hope that helps, and good luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)