Posted by Sherman in Idaho [172.68.133.69] on Tuesday, May 01, 2018 at 16:16:36 :
Thought I'd pass on what I found when the alternator in the '61 took a dump on me on a recent trip to Pullman, WA (about 150 mi away). Figured the brushes had worn out, but field terminals showed conductivity. Figured maybe the regulator died, but jumping field straight to battery made no difference. Armature circuit was open somehow. Coming back in the dark, I noticed the headlights getting dimmer and dimmer, pulled over while it was still running and measured about 9 volts on the battery. Got lucky and a local boy stopped and let me charge it for a while off of his truck. Got going again, left it running with the lights off while I gassed up in Plummer, but by the time I got past the Indian gambling casino in Worley, it was getting real dim again. Hoped I could make it to Coeur d'Alene, but no luck. No camping gear and no place to camp near the highway anyway. Pulled into the fancy new Worley fire hall just as she was starting to sputter and cough. Battery was down to 6 volts. Luckily a couple of firefighters were there and didn't mind being woken up at 11 pm. They gave the battery a real good charge from their beefy charger, and shared some of their pizza. I knew there was no way to make it back to Wallace (70 miles) with the headlights on and with no place to camp nearby the only thing to do was go back to the Indian gambling casino, hang out there all night, and wait for dawn. After a couple of conversations with "security", the sun finally came up and we drove back to Wallace with no issues (heater and lights off, of course).
Been driving around town to the lumber yard and such with no alternator ever since, but finally we got some dry weather so I pulled it. Was going to just buy a new one until I found out they're $70 for the regular old standard Mopar alternator that used to be $20. Figured maybe the diodes had been dying one by one and finally the last one gave out, but when I checked them, they were all good. Then I noticed the point where the three armature windings were connected together looked burnt. A little wiggling and they came right apart. Turns out the armature windings are connected (3-phase Y configuration) by a steel crimp sleeve crimped over the magnet wire. Once such a copper connection gets hot, the copper loses its hardness and oxidizes more and things go downhill quickly. All it needed was for the wires to be cleaned, soldered together properly, and insulated, and the alternator was good to go. Put it back in and it pegged the ammeter at 50 amps and then settled down to 10 amps and charged up nicely.
Point of the long story is sometimes it's an easy and free fix. Second point is to be aware of this inherent weakness in the design (steel crimp sleeve). I have two identical mopar alternators in the bone-yard that I took out of other rigs over the years, and I think I'll take them apart and see if that's all that's wrong with them as well.
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