I wanted to Install a 120 amp Alternator on My 84 300D. I decided to look for a used one on eBay.

Well I not having done thought research on the project ordered the wrong Alternator (From a 1995 Saab 900); I should have been looking for one from a Saab 9000.

So I had already paid for the Alternator ($40 with free shipping and they claimed the Alternator had been tested OK and had a 30 day return on it) and I was thinking maybe I could get it to work.
What I received was a Bosch Internal Fan type AL0780X and a quick look shows it is unlikely to Fit.

I took the Alternator to Autozone for testing and it Failed. However, I did not trust this test as the Manger did it and I simply was not sure then knew how to test it.
I let the eBay Seller know that the Alternator Failed and that I would have it tested again somewhere else to be sure.
I also told the Seller the I believe the Bearings sounded bad when the Alternator is spun.

One place said they could not test it and I took it to PepBoys got it tested; failed again and they give you a print out.
Contacted the Seller and ended up with My total cost refunded and was told to keep the Alternator.

So except for the time used up no cost to Me for my Mistake.

So I decided to take the Alternator apart to see if I could find what was wrong and replace the Bearings and other parts if it could be done at a resonable cost. I figured if I could not get it to fit My Car I could once fixed sell it to a Saab owner as it is an expensive Alternator when rebuilt.
Well the Steel parts on this Alternator are rusted way more than average and I will insert a link on repairing a similar Alternator so you can see pics of the Parts. The innards of My Alternator are the same but the Plastic end cover is different. Link below to see some of the ralated parts
http://www.oichan.org/mods/alter/alter2.htm
Bearing Replacement
http://www.3dzubehor.com/Rover/Boschrepair.html

Part of the reason for writing this is to issue a warning for those with Bosch Internal Fan Alternators (the Later Model Mercedes have them).
The Slip Ring on these Alternators is a Plastic Sleeve with Copper Rings on it that slides over a what turned out to be about 2-½ inch long skinny Shaft that sticks out past the Rear Ball Bearing (in My case the Bearing was badly rusted).

I did not want to try to pry off the Slip Ring because I was sure it would break if I did and I elected to support the outer rear Alternator Housing on Blocks and use a Punch to drive the Rotor Out.
Well, that bent the Slip Ring Shaft!

Just to see what I was dealing with I cut the Slip Ring and put deep Socket over the bent Shaft and drove the Rotor and bearing out of the Housing.

So if you have a later Model Mercedes Alternator with and Internal Fan and you are changing the Alternator Rear Bearings you have a choice of doing what I tried to do and maybe bending the Slip Ring Shaft or removing the Slip Ring and risking damage to that.
　
　

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84 300D, 82 Volvo 244Gl Diesel