I would hardly call it considerable. Look at the size of the wires that feed it. Compared to the cabin fan, it's noise.

Try disconnecting & cleaning the battery ground strap(small nut) beneath the rear seat..most likely not making a good ground there.

I will check the battery ground strap tonight.

Question: do my voltage readings indicate that the alternator is OK? It would seem that if the voltage can get up to 14.02 then the alternator must be capable of putting out a decent charge. I know voltage is not the whole picture (need to measure amps too) and so I am pulling the alternator tonight to have it bench tested. But am I wasting my time?

M.B. Doc, you may have hit the nail on the head pointing out the grounding nut. I'm not positive of that yet, but with all the hours I have spent, this is the closest thing to evidence of high resistance that I have found anywhere in the system. See pics of both sides below. Is this enough corrosion to cause the problems I described? The dealers are out of stock - can this be cleaned with a wire brush/drill and contact cleaner? Or should I try a generic cable? A cable is a cable is a cable, right?

FWIW, I pulled the alternator and had it bench tested 3 times, and it passed. I'm getting ready to take the battery for a load test - should I bother?

http://i35.photobucket.com/albums/d1...k/DSCF0035.jpg

http://i35.photobucket.com/albums/d1...k/DSCF0028.jpg

Dc Power Output
 

1984 300d Turbo 140,000
Clean With Wire Brush Or Replace Cable With Same Size Take The Old
One To Any Auto Store And They Will Find One To Use, Maybe $5.00

i saw another ground strap looked just like that in a 210 e320.it had been flooded.

So are we all in agreement that this is the culprit? Meanwhile, I soaked the cable end and the nut in hydrochloric acid for 20 minutes, rinsed, wire brushed, soaked in acid again, rinsed, then filed until shiny. Due to close quarters I am just wire brushing the stud at the chassis as best I can. I will post pics soon.