So I took a day off from work for some wrenching on my fleet of vehicles, and on the Mercedes front, I got the old FUBAR alternator out (original discussion on this thread):




It looks like the nut backed off and caused the belt to slip off the wobbling pulley. I don't know how I did not catch this, or why it would have happened! It would have probably been functional had the nut not loosened, but it was probably close time for a new one anyway. Regardless, it looks nasty now with the grooves that were cut by the fan!

I also my new alternator all tricked out with the clutched pulley:



A few questions on wiring: the original alternator has the three prong terminal connector. I can see the two large terminals are joined on the old alternator body, and marked B+, and the smaller terminal is marked D+:



What is the module in the bottom of the photo that is attached with a single phillips screw and connected with a blade connector?

In contrast, the new one has a screw terminal for B+ and D+ as well as a blade connector marked W:



From googling around, the W seems to be for an tach signal, so this is unused in my case, yes?

My question is this:
Can I just cut the harness and solder/heatshrink in the bolt on style of connection terminals. Joining the two large connectors into one and connecting to B+, connecting the smaller one to D+ and leaving W+ unconnected?

I'm not terribly concerned with keeping everything 100% original, I just want to get it working in the most reliable manner possible. The new alternator will be slightly underdriven, and I have no large electrical loads in the vehicle, so I'm not concerned with the approximately 25% additional current the alternator can supply. The upgraded alternator was appealing since it is of the more modern internal fan type. Should result in reduced noise and increased efficiency, especially with the clutched pulley.

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Garage:

2017 Chevy Colorado Diesel (nanny state emissions)
2005 Volvo S40 T5 AWD, 77k
1987 Mercedes-Benz 300D turbodiesel, 4 sp auto, 156k - 28.7 mpg
1996 Tracker 4x4, 2 door, 16v, 3 sp auto. 113k - 28.6 mpg

WARNING: this post may contain dangerous free thinking.

W+ is an AC feed which is usually used to drive a tach. It's unnecessary in your vehicle. If you find you are getting radio noise, you can use it for a suppression capacitor, otherwise ignore it.

On your old alternator, there are three terminals. The two large ones are both B+, for some reason Mercedes used two cables for many years. The small tab is D+, which provides excitation current and operates the dash light. You have corresponding terminals on the new alternator.

What I would suggest is to run two new wires. The first would be a small wire for D+. This can be 14 or 16 gauge, as it won't carry much current. The B+ wire should be heavy...maybe 4 gauge would be appropriate, or you could probably get away with a pair of 10 gauge wires if you want to do like Mercedes. Where these will go is to the junction box on the right apron, near the battery. Once the new wires are in place, the old ones can be disconnected and taped off.

I'm not sure about that pulley. A larger pulley won't work well with your belt system, unless the alternator itself is a smaller diameter than stock. It will also derate the alternator, since it will turn more slowly, maybe that's what they meant by 90A.

Attached Thumbnails

   

http://www.peachparts.com/shopforum/performance-paddock/53237-installed-143a-alternator-my-w124-86-95-e-class-photos-2.html

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