Excellent (and large) photos that should help others. Didn't look too corroded, at least to those guys in the east, but aluminum is very unforgiving. I once had a Chrysler alternator that wasn't charging, and ditto for the replacement. I then thought to run jumpers from case to BATT- and it then worked. It was just bad grounding of the aluminum case. Another time I had the cluster on my 300D pulled out and saw smoke coming from the speedometer cable as I cranked the starter - corrosion in ground strap to alum case of tranny and it was using the speedo cable as the current return path.

Interesting spur-gear tension adjustment on that 1978 alternator. My 300D's have a finicky bolt & nut tensioner that likes to destroy itself. All that seems a bit over-kill. On my old Chrysler cars, you just tighten a nut while you simply pull up on the alternator. You don't want the belt too tight anyway (wears the bearing).

Thanks I wish this forum was like benzworld and they resized to a smaller dimension to make it easier to read the thread.

I checked the voltage in the parking lot and it was reading at 12.1v at idle. I am kind of concerned but when I push the linkage it increases with throttle. I am thinking the battery is just drained and I was driving with the lights, acc and radio on. I feel like I may have to upgrade the alternator if this continues or see if I can find a drain. I have also started the car about 6 times and driven the car maybe 10 miles tourist are here and you can't go over 35 on any freeway right now...

Oh I have that on the 82 and that is such an easier way to tension the alternator. The starbolt is right behind the belt and attempting to get a wrench on it to turn it is a huge PITA plus on the 78 you have that huge york compressor blocking any access above. Its underneath or blind. I hope I don't need to take it off again..I know the Chrysler route! I had a dodge I remember use the tire iron to pray it over and tighten the bolt.

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12.1 volt may be normal while idling (especially if you are using juice like headlights or blower) depending what your idle rpm is set at and the diameter of your alt. pulley. As long as it goes up above 13 .4 volts or so when you rev the engine above 1500 rpm the alt is probably ok.

"Then I had to go over the stator. Cleaning, sanding, cleaning, sanding and finally painting. I went blue."

IMO that was unnecessary and could have harmed it. The coating on those copper winding (called magnet wire or enamel wire) is very thin and should not be touched beyond using a paint brush or blowing with compressed air to get rid of dust. Solvent in the paint, if not compatible, could melt the thin coating.

That new Brazil made Bosch voltage regulator does not look familiar. I'd put the old one back in if it was working fine since it was already "burned in" and time tested. Unlike vacuum tubes, voltage regulators, being a semiconductor device, does not wear out or burn out unless abused.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Slip ring surfaces look very rough and will wear the carbon brushs prematurely. If needed, it should have been done on a lathe.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

That is what it was doing, it shot up to that as soon as I applied throttle.

The copper was never touched, I know that most copper used in electronics is treated with an agent to keep it from tarnishing/aging. Only the steel areas that were meant to be polished were touched. The stater steel housing was sprayed to keep rust from spreading in between the windings/panels of steel part of the starter and it was also sprayed to keep the insulated coating that was still intact..intact..Also you forgot to mention there is cardboard in between the windings of both the stator and rotor. Any cleaning or soaking will destroy these.

The old regulator is toast, the brushes are to sort to touch the slip ring thus causing me to do this rebuild.

Yes but they will not wear the brushes out as bad as if I had installed the voltage regulator with the sliprings looking like this.



The Alternator really needs to be replaced, it is bad but I did this to get another few years out of it and also it shows "WHY" one shouldn't just replace the voltage regulator on a alternator they have no idea how long its been in. As it will look like this inside and a voltage regulator will not fix an old greasey, crusty and rusty alternator.

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