I thought about what you said about the relays Ax. I do have relays in the headlight circuit, but I have that wire temp disconnected while I'm checking out the alternator. (It was hooked to the power post on the alternator.) Also, the clutch on the new A/C compressor seems to engage easily and completely. So, you think that maybe the 12.5v is fine because that's all it needs to put out? Thanks, Jag

 

As long as it keeps the battery charged it's fine. Too much output when not needed can overheat the battery and boil the electrolite spilling acid and damaging the plates.
What about your stalling issue? Let me research the diode fix.

 

The stalling issue went away when I returned the non-Ford alternator and installed the present one. That's a step in the right direction. Jag

 

John, sounds like you are close to a solution you can live with. If you are still interested in finding out why things are behaving the way they do, I'd suggest two things. First, read through all the information on this web page http://www.powermastermotorsports.com/faq_s_-_chrome_alternators.html. They discuss the one-wire Ford alternator as well as general installation and operation issues with all one-wire alternators like pulley ratio issues, alternator turn on RPMs (cut-in point), etc.

The second thing is obvious to somebody with your experience - diagnose the problem one step at a time. Start with the simplest setup - nothing attached to the alternator output except a battery.

1. Disconnect the output wire on the alternator that goes to your truck battery. There should be nothing connected to the alternator at this point.
2. Get hold of a usable spare 12V battery. You must have one sitting around in the garage.
3. Charge the spare battery fully with a battery charger.
4. Use the negative side of a jumper cable set to connect the spare battery negative post to a good ground on your truck. Somewhere on the alternator bracket would be a good choice.
5. Use the positive side of the jumper cable set to connect the spare battery positive post to the output from the alternator.

Now you have a totally separate circuit to test the alternator on your engine without worrying about lights, A/C, etc.

6. Start up the engine.
7. Rev the engine up to make sure the alternator has reached it's cut-in speed (around 1200 engine RPM with a 3:1 pulley ratio). After it reaches its cut-in speed once, the alternator will continue to charge even at low RPM until you actually stop the engine.
8. At 2000 engine RPM, the alternator should be putting out 14.5V +/- 0.5V. If it's not, check your pulley ratio and your voltmeter. If the pulley ratio is 3:1 or so and your voltmeter is OK, you either have a bad spare battery, bad jumper cables, or a bad alternator. Those are easy to check to find the one bad item.

None of this is hard to do, expensive, or time-consuming. It WILL absolutely tell you if the alternator is working on your engine with a standard battery setup. From there, you can add things like the A/C, lights, etc. to check out each accessory in turn. Have fun and I hope you get it sorted out.

 

Mine did not come with any instructions worthy of note. While we're on the topic, how do you wire the idiot light? Mine's a 59 F100. Thanks.

 

1 wire alts connected right to the Batt.. thats it.. That why there so simple.. and the idiot light cant be hooked up to it... At lest there no why I know of.. I run just a Amp meter and a volt meter so I can tell if there a problem myself

 

Krautwolf is asking about the other lead coming out of the back that I guess is standard on these things. The one on my unit is orange with a fancy plastic clip. The clerk where i Bought it read something out of his manual to me that said it was for the idiot light and that If I didn't want to use it, then I should not hook it to anything. George, the extra battery idea is great! And thanks for the link. I tried the alternator again this weekend with no output. I tried the idea from Ax by attaching the volt meter from the output lug of the alternator to ground. I am getting zip, zero, zilch, zuchini and any other z work I can think of. Also, after about 5 minutes of running, the pulley on the alternator was so hot that I could barely touch it! So I'm off to see the manuacturer again today.

 

John, that link I posted explains how to use the second wire to run your idiot light if you want. I don't remember the details, but I think they are there. If you read through all the FAQs, I think they talk about a jumper that's required on the second wire for some installations.

 

Hot from the belt slipping or from a bad bearing?

 

Ax, I'm thinking it was from a bearing prob, but if it was the pulley slipping, wouldn't it squeal? Hum.... Slipping pulley means fewer rpms, which means the alt. may not be getting up to proper operating speed.... I hope all this isn't for nothing more than a slipping pulley. When I take it back to the manufacturer today, I'll check for heat on the pulley again. George, I think I'm going to leave the idiot light wire alone, but Krautwolf may try and report back. Thanks, Jag

 

Sometimes the belt won't squeal, but the pulley and belt will get a shiny glazed look.
You would most likely feel a bearing that's bad enough to heat up like that if you turn the pulley by hand with the belt off. The rebuilder should have a test stand to test it on. We had a homebuilt one we used at the service station to test old ones or ones we rebuilt.This is really a strange one, alternators usually work or they don't, if they don't work the most common problem is a blown diode or bearing, both a relativly easy fix. If it was a bad winding, we didn't bother with it.

 

This guy answering the question
http://www.hotrodders.com/t62803.html
seems to know a lot about the subject.
I especially found his test for an charging alternator by checking for magnetic field at rear bearing with a screwdriver very enlightening.

 

Thanks Ax, another nice link! I am learning more about alternators than I ever really wanted to know. But I need to learn so I can figure this thing out. I just came back from the manufacturer's shop. The alt works great! Again He suggested that I check the belt to see if it matches up with the pulley. He also suggested that I attach a wire directly from the bat to the power lug on the alt just to see if it makes a difference. At this point I am thinking that the belt may be the problem by slipping on the pulley. I'll give it a try and report back. Jag

 

The top surface of the belt should be even with or slightly proud of the pulley edge. If it fits down into and/or touches the bottom of the groove it is too narrow. Probably easier to change the alt pulley in that case than the belt and other pulleys. Belt dressings are only a temp bandaid.
Where did you have the power (output) wire going before? GM style replacement battery cables have a pigtail wire attached to the terminal clamp for that purpose.

 

I have an old Sun Equipment VAT-25 carbon pile tester left over from my wrenchign days. Its not as fancy as the VAT-40 and up that had inductive pick-ups but its a nea thing none the less. You can also buy those hand held battery adn charging system testers that have a small carbon pile in them for putting a load on the system. Nowadays you can get a fairly cheap one for about $20 from the chinese tool places

Good luck Jag, sounds like you just about got it licked

Bobby