When a working alternator (in this case, a Bosch 80A) is removed from an M20 (in this case, an M20B20) for a couple of months, detailed (lightly cleaned, not disassembled, panited aluminum, rubber mounting bushings replaced), reinstalled and does not charge, what is the likely culprit? And how do I test it for output without damaging it? This car needs to be dependable by early Thursday morning . . . so if the problem can't be resolved with the current alternator, then will the one from wifey's '87 325e interchange? I hate few things worse than playing "musical parts" with my cars, but . . . Jeff Dreibus 1984 320i 5-Speed 1987 325e Automatic Too Lazy to Post a Real Sig
Perhaps use realoem.com to compare parts numbers - same part number, then no problem. Different part number, then the question is, what's the difference. Bentley manual I think details testing procedures, including the voltage regulator. Might be worthwhile to get the battery tested, if it was marginal at project's beginning, it may have gotten to the point where it won't hold a charge anymore. Only other thing I can think would be the probably unlikely oddball possibility of paint somehow getting where it shouldn't have and affecting the alternator's operation - but, that seems unlikely to me.
Interstate battery is one year old and never had any problems. I will see if I can test it and, failing that, check the Penske site. Thanks. Jeff