I'm posting this info because I ran into numerous snags upgrading my w210 alternator (some minor, some not)- and it would have been extremely helpful if I had some of this info before I dove into this seemingly simple exercise. Thanks to all of you who posted on this job and these threads, because in the hours I spent gathering info before doing this swap- I know I was able to avoid some major problems.

First, IMO if you're going to change your alternator in your older (95-96) e300, it only makes sense to upgrade if you can. My experience was that the 90A model was woefully underpowered for this car, especially in cold climates- with the defroster running, with headlights & fogs on, windshield wipers running, radio on to tell you of how unfortunate you are to be driving in sleet/snow/pouring whatever, etc. My headlights were always dim and I was often concerned when my wife had to drive in terrible weather when she drove the 300.

If you are considering upgrading your headlights and/or stereo system to include power-hungry amplifiers, and you have a 90A alternator, IMO you really should seriously consider upgrading your alternator- for your safety...

Next if you're going to change your alternator- there are alot of posts that point out that poor grounds can cause problems too, so you should check them. Do this as part of the job. You will have to pull the rear belly-pan to find the big ground strap that (for me anyway) was a major problem. A related thread is here. Go there and meet the jolly green ground strap:

W210 ground strap location?

Since the motor mounts are insulating and non-conductive, these straps are really the only thing proving a proper ground. I was shocked to find the resistance of the primary ground strap to be out of my multimeter's range! Check that thread for more info on that. There are numerous other ground points and after 15 years they could all benefit from some attention- so get some 100 grit sand paper, and some silicone anti-corrosive grease and get after it. Don't forget the one under the rear seat where the battery's negative post grounds. I thought it would be perfect because it was in the cabin- not so!

The sticky about swapping the alternator on a w210 describes removing the fan shroud. I wish I could have easily done this, but the fan shroud on my e300 slightly covers the tips of the fan blades, and would not clear the fan for removal. So- I worked around the shroud and the fan. The fan also presented issues, because I had to insert the alternator bolts between the fan blades. Routing the new serpentine belt was ridiculous. It just takes more time, and alot more patience. If your model lets you remove the fan shroud- I'd do that for sure, and I'd probably swap the tensioner pulley and serpentine belt just because you could do so fairly easily.

Another issue is that the 143A alternator I bought was a remanufactured model as pictured above. One problem I ran into was that the alternator initially would not fit into the mounting bracket. I realized that the body of the remanufactured alternator had been repainted to make it look nice. The problem was that the multiple coats of metallic paint prevented the thing from fitting into the gap properly. Since I was taking a plunge here and found NO definitive info saying this alternator would absolutely fit and work in my upgrade-application, I was worried about marring the mounting surface of the alternator because I wouldn't be able to return or exchange it. Well- I decided to just sand the paint down a little at a time, and the mounting bracket too- and that did the trick- it eventually slid right into the bracket like it had been meant to sit in there all along. Oh- and to save you some hassle- install it from below.

Tensioners- There are multiple "w210" models, and the info for one, doesn't necessarily apply to another. I appreciate the helpful info for changing an alternator on a w210 in the project stickies (especially the torque values), but was confused and frustrated when the article described loosening a belt on a tensioner I didn't have. My tensioner looks like the older MB models. As described in the ground strap thread above for another forum member- you release the tension on this tensioner by placing the tip of an old fashioned tire iron in the hole (circled in red in the pic), remove the nut from the bolt, and slide the bolt back toward the engine while maintining pressure to the left on the tensioner spring using the tire iron, and slowly, carefully bring the tire iron to the right to relax the spring and the tension to remove the belt...

More to follow...