Just a not of one more item to check. For the past couple of years, my 230SL has had a "weak" battery that I put on a charger every so often. I first credited it to infrequent driving. Then after driving more, I credited it to a corroded battery wire and terminal. This weekend, after driving an hour in the rain with my lights on, my battery was almost dead. After driving home with the lights off, everything was fine.
I removed the alternator and had it tested by a local shop, he said that it was fine. I then replaced the voltage regulator on the fender and everything appears fixed.
I popped the top off of the regulator to reveal the mechanical contacts were badly pitted. The replacement Mercedes regulator has a solid state switching circuit that should last forever.
Moral: If you have the original regulator in your car, think about replacing it with the newer solid state regulator. Mechanical electrical contacts do not last forever.
Jim Villers
190SL, 230SL 5-Speed, 190E 2.3-16 Kompressor