Yeah, I said "alternator".

Just about the time I thought I'd get to drive Grover a lot more, the alternator has crapped out.

When I converted to 12 volts a few years back, I used the alternator off my '65 Mercury Comet, because, well, it was there, and Ford used that style alternator for quite a few years. Everything has worked fine untill recently, when I began to notice that the amp gauge needle quit moving when I'd turn on the wipers, lights, turn signals, or any of the other two or three electrical accessories I have on the truck.

Then, of course, I needed a jump start after stopping to get gas one day. Thank goodness it was a fellow Ford truck driver that helped me out. I don't think I could have overcome the shame of getting a jump from a Toyota or Chevy.

I hooked up the old multi-meter to it today, and I found that it's only putting out about 12.4 volts at the battery, which drops to about 10.8 when I turn everything on. Obviously, there is a problem. The alternator and the (electronic) voltage regulator only have about 12-13,000 miles on them. Any ideas what my problem is, and more important, what might have killed my alternator?

 

Sounds to me like the alternator is bad. I believe it should be putting out around 14 volts to the battery when charging properly.

hotrod48

 

two different things, right? The ammeter gauge still moves to discharge, when you turn on headlights? Right? If it sort of stays in the middle, when engine is running, or you can see slight brightening when only headlights are on and you rev it *(or see small rise in meter V), probably one of the main diodes is open or shorted. If you don't see that, probably regulator or wiring. Especially check brush and brush holders..brush can stick in sliding place , or can just be worn out. Most common problem in alternators. In any event a kit is good and cheap, you can do it. I do not know this particular alternator, but this is what goes on. If you have a red bulb on dash, check wiring around that too, one side goes to ign +12, other to alt term. It has to come on before you start car, or alternator will not charge, as it starts the alternator by current thru it, if you have it. There are more complex diagnostics, but one quick check is to see if one of the field wires has volts (should have, with key on (not main output wire) ; other one may or may not have volts, depends on regulator and if you have two wire field, but generally 2nd one will have a much lower voltage on it when starting/idling. (difference is running field magnet)If it is also 12 V like the other , regulator or wire to it is no good, if external reg.. sorry for general help nature of this. I know how they work, but there are variations in how they are packaged etc.

 

Yeah, I did mean the gauge, the one Henry mean the truck to have. On the '54 (and it's siblings) it has an inductive pickup, and of course reads
-D*C+. No idiot light, however.

The crazy thing is, the needle doesn't move AT ALL, under any circumstances, which is a new one on me. My guess is that that means no respectable amount of current is flowing.

Stuck brushes are a possibility, particularly since I haven't driven the truck that much since I installed the alternator (which, by the way, was a new rebuilt unit), so over the years there might just be a tad of corrosion built up for the brushes to hang up on.

I think I'll yank the alternator and regulator both off and take them to a little shop I know of.

 

Needle may be just stuck in gauge, as unless someone rewired it, it has to read discharge when headlights come on..no way that can't work, except stuck needle, or wire fell out of U shape those guages sometimes use(real ones have two studs on back just as henry did it). I say that as maybe nothing is wrong , and it is only the needle and a dead battery caused by some unrelated application of Murphy's law. Don't want to run around alternator on nuttin, right?

second, with no idiot light, something has to start up alternator..Light is not there just to warn you,it starts alternator field. it will not charge consistantly without it, or only very weakly. I don't know who figured out wiring of late alternator into early ford at 12V, but often not done right..it is not as easy as it looks. My 58 was converted from gen to GM alternator, wired all wrong, weak charge, blew regulators. (that is why I got a good deal) Ripped out ball o tape deal at alternator, re did it correctly, no pronblems. If no light, a resistor is added between ign and one field term to start it. How was it installed? I think the comet would have had the light?

 

I know when my vehicles stop charging, most of the time the problem is the voltage regulator. The early ones had points in them and wore out pretty quick. The new ones are transistorized and a little more efficient. The regulators are fairly cheap, so that would be the first thing I replaced. If it doesn't cure it, then I'd pull the alternator and have it checked out or rebuilt. You may try using a volt meter instead of the gauge you got. That would give you a more accurate reading.

 

Actually, I was using my trusty digital multimeter. What I WISH I had was all the gear the Chilton's manual says you need to do a complete diagnostic on the alternator. It was the lack of action of the dashboard amp gauge (and the need for a jump start) that alerted me to a problem.

 

If your that positive its the alternator, you can pull it and take it to a Kragen Auto Parts, they'll test it for free.

 

We don't have any Kragens here in Kentucky. However, there is a little automotive electrical shop in Lexington that has been around since shortly after Henry Ford pushed his first car out of the shed, and they're pretty reliable. Failing that, I have a brother-in-law who is my "in" with the local Carquest franchises.

Fortunately, removing the alternator is pretty easy. Since I fabricated the mount, etc., I'm pretty familiar with how it all goes together.

 

Ed's right. Get that alt tested. There are many places that will do it for free. If it's good, then the next logical place to look is the regulator. They will test that for free too. Good luck, Jag

 

Most any auto parts store will do a free altenator test for you. Autozone, O'Rielly's, Carquest, Pepboys, Western Auto, etc.