Folks,

66 Satellite with 68 440 Fury engine, MSD ignition with MSD distributor....third unit has died since October....2 were Napa, one was Autozone supplied...tension good, no squealing....coming back from 150 mile trip Sunday, dang thing dies with 30 miles to go....

Any ideas of the cause?????

Thanks, BAMMER

A guess... and some questions. 3 alternators from 2 vendors strongly suggests something amiss in the car's wiring or VR. Its possible the alternator is running at excessive voltage to overcome a weak connection in the main charge wires. I'd trace and inspect the wiring and connections from the alternator output stud to the bulkhead connector and bulkhead connector to the battery. Check the fusible links too. Pull the bulkhead connector and check for damaged terminals. Check the ammeter terminals for signs of corrosion or loose connections.

One way to check is to put a new alternator in and use a meter to check voltage at the alternator stud and the starter relay stud with the engine running at fast idle. At the starter relay stud, you should see 13-14 volts and about one volt higher at the alternator. If the alternator is lots higher, you have a weak connection or wire in the system.

Now questions. Does it fail by simply stopping charge? Any signs of bearing distress like noise? Have you had any of your failed alternators tested? Some parts stores will do this for free. If so what did they tell you? Did you replace the voltage regulator with the alternator?

I rebuild my own alternators and have for 30 years for that very reason. The rebuilds at the chain stores have always been poor. They have one moving part, 4 wear items yet they all seem to be a pain for rebuilding companies to figure out.
Nothing in your list of items draw a lot of current. I bet there is nothing wrong, just a run of bad alternators.

Craig

What is failing on the alternator?
Windings, Brushes, or Diodes?
Which alternator is it, the stock 1968 type with the single wire to the field brush, or the newer style with two connections to the field brushes?
What is the maximum RPM the alternator is seeing (max engine RPM x Pulley ratio?)

I went through 4 alternators at two parts store, NAPA and O-Reillys. Two made noise when rotated on the counter and the other two would not rotate without hitting something inside. Whatever companies are doing their rebuilding needs a lesson or two. They even visually looked crappy. Finally got one from Autozone that was OK.
Ron

I'm having the same problem with my 69 Satellite bracket car. I go through an alternator each year. Just last August now this past weekend. On my car its shorting out & draining the battery between rounds. I talked with the guy at the parts store I mostly deal with & he said in discust that the problem is Chinese rebuilds. He says they are junk. He pulled two from the shelf to test & both where bad. One had a broken terminal stud on the back. I too thought about updating to the newer style alternator. However I have read on here that the wiring needs to be updated to handle the amprage. So I guesss I will just have to carry a new spare with me.

The mancini comes with the wiring diagram, and it eliminates the voltage regulator.

Which one that mancini has that eleminates the regulator. How many amps is it. Is it round or square back??/

We'll what is the biggest alt. that you should run with only a fuel pump, elect. fan and big fan nthat draws 60amp on start and 45 running

As posted above it could be 3 bad alternators in a row. Plus there is benefit to upgrading to a newer alternator. Still, there should be more diagnosis. Why did they fail? Try to get them tested and check your wiring! Even if you don't find much, its time well spent on an older car.

Thanks all for the replies (been outta town)....I actually spent the whole winter rewiring the engine compartment and power thru the dash...I have a technical background and made sure I did it right....I will have the alternators checked out, I really think I am getting crap, heck, I got one from NAPA before this that was dead on arrival, no output. I am gonna check into Mancini...i think I am getting what I paid for with a 45 dollar unit!!!!!

Thanks again

I had a similar issue, tuned out the alternator field wire at the harness disconnect (by the right rear of valvecover) was partly popped out of the connector and grounding out on the block.

Saturday I went looking for a replacement alternator. I went to the parts store with the bad alt. & reciept in hand. They checked it & it was bad. Didn't have an other. Called a nearby sister store & they had one. Drove over. Had them check the new one & it was bad. They called another sister store. They had one & checked it before I drove over. It was good. So for now my car is working again. Think I will buy a spare so I can fix it at the track if need be.

Wow... lots of bad reman alternators getting sold (and returned). I hope the chain parts stores wake up and find better rebuilders. If I need a square back some day I think I will go the Powermaster/Mancini route.

I recently had a similar issue with my freshly restored '65 300 'vert. The Alternator would not charge. I went through 3 alternators as the tester at O'Reilly's was not working. When the third wouldn't charge I took it to Autozone for a test assuming I would have to get my money back from O'Reilly's and purchase a new one from Autozone. They put it on the tester and it passed. I then changed the VR with a known working unit, no dice. I checked all the voltages with the key in the On position and the ignition wire disconnected from the Ballast and all the voltages were within spec. I was at a loss. I disconnected the Field wire at the Alternator and VR and attached a wire to the two external from the harness. I fired it up and the Alternator charged. Long story short, my brand new Bill Evans Engine Harness had a poor connection at the Alternator side of the Field wire. After removing the black plastic shield, I saw the connector was primarily crimped to the wire jacked and wasn't making a good connection with the bare wire. I installed a new connector and all is good. Don't discount the harness.

Thanks for all the replies.....yanked out the alternator today and the dang field connector shows a short to the alternator casing which of course grounds it when installed.....tok out the field connector and the metal inside is grounded.....took out my last bad unit from Autozone and the 12v OUTPUT lug is shorted to the casing.....I can't win......going to Mancini....

BAMMER

THANK YOU ...4 posting this...my 71 challenger eats 1 a year pretty much to the day so at least now i know when i have 2 take it back 2 auto zone....just goes 2 show you i live 20 minutes away from MANCINIS..and i wish i'd known about the alternator problems as far as defective..thanks MOPARTS...and fellow Mopar addicts..