I keep burning out my alterator in Model 115. Is there anything-like a short that might be causing this. Can I rewire to be sure? Where do the 3 wires from the alternator lead to? I don't have a diagram for the wiring. Is there an internet source for diagram for model 115? Is the igniton switch or start switch related?

Pat McDonnell,

When you say you keep burning it out, what do you mean? What are the symptoms that lead you to think it is burned out? Does it literally burn, or what is the failure mode? Stops charging? Battery dies? Starts squealing and siezes?

Do you rebuild it and put it back in or do you buy a new one and install that followed by another failure? Is the failure mode the second time and third time the same?

The problem diagnosis will be more successful if you give us some additional data. 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)

The three wired plug on the early alts went to the voltage regulator. The complete brush holder can be simply replaced with the common cheap Bosch internal regulator used after 1975 (I think). Part number 30 060 (I think).

By doing this one has eliminated the harness to the old regulator (and the need for the regulator). At that point there are two wires and maybe a ground. I would look closely at the ground. The alt is rubber mounted and needs a separate wire. Leaving the ground open could take out an alternator rather quickly.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

HI Pat

One thing. What brand alternators are you useing? I only use and recommend Bosch remans. Ones from "as cheap as I can sell" parts stores often are of lesser quality. Just my 2 cents worth.

fasthair