2 Dead Alternators

[KStew67F100]

I have a 67 F100 with a rebuilt 390 and rebuilt transmission. As it says in the title, 2 alternators have died on that truck in the past 6 months. The first alternator was put on last September after the engine was rebuilt and died about a month ago. However, the truck was not driven too much since last September... maybe only a few hundred miles. I went ahead and got a replacement alternator about a month ago, which seemed to work perfectly until today when the truck died as I was pulling into the garage at my work. This time it's only been at most a couple hundred miles that I have driven on it. I don't have too much pulling on it... only the charging system and lights (no A/C, radio, etc.).

Has anyone experienced this before and could give me a clue as where to start resolving this issue? Any help or comments would be much appreciated!

[Mach428]

You didn't mention how you know it's the alternator or where you purchased the unit. I have found that the units at Autozone and the like are garbage. I have gone through several and finally bought original Autolites rebuilt by a reputable dealer on ebay. No more problems.

How do you know the alternator is your problem?

[KStew67F100]

Mach428, when the first alternator died I couldn't even start the truck since the battery was drained. I trickle-charged for half a day and it gave me another 50 miles to get home. I took the alternator off and had it tested... it was dead. Fortunately, it was still under warranty so it was replaced at no cost. I haven't had this second alternator tested yet since it died as I arrived at work this morning, but I'm assuming it's pretty much the exact same issue considering my truck "acted" the same way before it died. Plus, I was not able to start it up again since battery was drained. The alternator was purchased at O'Reilly.

Could you provide information about the dealer on ebay? I'm hoping it's just a bad alternator and not a short somewhere electrical system that's killing the alternator.

Thanks for your help!

[Mach428]

I've had fantastic quality and service from A1 Truck in Sparks, NV. You can look up John's contact information either on ebay or the Internet. He restores original Autolite alternators upgrading with 65 amp internals. The best I could find from any of the auto part stores was 40 amp and again, I went through several before giving up on them.

John's price is less than $100 but I figure my time and labor are worth the effort in constantly changing our bad alternators.
Since your battery has been totally discharged several times, you may wish to have that tested as well. Also, do you have an alt gauge or idiot light? This should confirm if your alternator is doing its job but the battery is just to weak to hold a charge.

Good luck.

[KStew67F100]

Thank you! I will take a look and see what he has to offer.

Concerning my alt light, it is currently out and I haven't had a chance to connect up the alt gauge... I think that project just got bumped up to "high priority" on the project list, haha.