Gents,
I replaced my original alternator at 140K last Thanksgiving. The truck is a 93 F150 4x4, 300 5-spd. . The "battery" light had been glowing, and after charging the battery a few times, I plunked in a reman unit from NAPA.

Well, I just noticed the light on again, and the guage showing me losing juice. Should I suspect the alternator again, or is there something I'm overlooking. Battery charges well and seems OK.

Is is possible that a bad component could be killing alterators? My (limited) understanding is that the charging system is pretty simple, and there's not much to replace.

Any help would be greatly appreciated. Thanks...

 

GO TO AUTOZONE OR SOME AUTO PARTS STORE THATS TEST ALTERNATORS, THEYLL TEST YOU ALTERNATOR, ALSO LOOK FOR CONNECTORS THAT MAY BE CORRODED OR DIRTY.

 

It would probably be a good idea to change the regulator at this time also and don't forget to check for a dead cell on the battery.

'82 F150 2WD w/351W (orig 300 I6)
Slik

 

Make sure the belt is tight,and check the battery connectors. Although I havent had any problems with the electrical system Ive heard from more than one person that fords tend to have problems with the ground side of the electrical system???, I dont know why. Its not uncommon though for aftermarket electrical components to have short lived lives, (unless your running high dollar replacement parts). Ive had replacement starters on other vehicles go bad repeatedly after only about 6 months, then get another one from the same manufacturer that lasts forever. Also are you running many aftermarket electrical items,(off road/driving lights, high power amplifiers,etc.) they can overwork your alternator into an early death also. I have had good luck with custome wound alternators(for more amperage) from local auto electric shops, they usually have one already rebuilt and rewound on the shelf in the shop. Later,
Jeff

 

Well, it looks like it may be the battery after all. I put a full charge on it last night, but as soon as I started it up and put on the headlights, I could see the gauge start to drop (kinda like the gas gauge in a 60's muscle-car, where you can almost see the level dropping!).

Anyway, if I turn off the lights, fan, radio, etc., then the level climbs almost to normal, but as soon as I turn on anything, even the parking lights, it starts slowly dropping.

The battery is a monster Die-Hard that is only 1 year old, so I'm off to Sears today to get it tested and see about that free replacement.

 

Vapor ,
Inspect the ground wire on your truck closely , it not only grounds on the starter but also on the frame . Ive seen them deteroiate at the frame . This will cause lots of problems that mimic alternators , batteries and a whole host of electrical problems . You can check the alternator output by hooking a DVOM to the pos and neg posts of the battery and start the engine . You should see anywhere from 13 to 14 V output .
Paul

 

That's what I like about you guys. You all give me plenty of excuses to go out and get some new tools. Anyway, I replaced my ancient tester with a Digital unit.

The results (at the battery):

engine on: 12.95v
engine off: 12.94v

Does that mean the alternator is no longer up to snuff? The ground wire is in good shape, and thanks for the tip, Paul. I hadn't noticed that little connection to the frame before.

 

>That's what I like about you
>guys. You all give
>me plenty of excuses to
>go out and get some
>new tools. Anyway, I
>replaced my ancient tester with
>a Digital unit.
>
>The results (at the battery):
>
>engine on: 12.95v
>engine off: 12.94v
>
>Does that mean the alternator is
>no longer up to snuff?
> The ground wire is
>in good shape, and thanks
>for the tip, Paul.
>I hadn't noticed that little
>connection to the frame before.
>


Hmm, with those results- something tells me that the charge from the alternator is not getting to the battery. Try checking the voltage at the starter solenoid while the engine is running- put the positive lead on the solenoid lug and the negative lead on the battery negative- you should get 13-14 volts. If you do, then the problem is in the positive cable going from the solenoid to the battery. If you don't, then your alternator is not putting out a decent charge.

Dustin Siebert
mrlaserboy(No Email Addresses In Posts!)
Home Page: http://www.fortunecity.com/silverstone/gear/40
Registry: http://www.superford.org/cgi-bin/sf.cgi?uid=default&vr2=1&ID=201
'88 Bronco XLT 302EFI/AOD/BW1356,44IFS(open),8.8(open)/3.55/31"

 

Well, I was driving home tonight, ready to rip out the alternator and get it to NAPA before they closed. A couple of miles from home I notice th idiot light has gone out. I figured the bulb burned out, but I took another reading across the battery. This time, it was 13.73v, right on the money.

I want to thank everyone for the suggestions. Looks like I'll be doing a bit of detective work this weekend...

 

Try replacing your voltage regulator. It sounds like it is not directing the voltage the way it should. They are cheap to replace and all the other components seem to be working correctly.

'82 F150 2WD w/351W (orig 300 I6)
Slik

 

The voltage regulator is integrated into the alternator case on these "newer" trucks. I wouldn't bother cracking the case open on a unit that is still under warranty. Less of a hassle (for me, anyway) to rip out the unit and exchange it.

Of course, since things are now back to normal, odds are I'll put off doing anything until the truck leaves me stranded late some night.

 

Vapor ,
Have a close look at the Pos cable too . Sometimes acid migration will work its way inside the cables . Sometimes aftermarket alternators do odd things ...Be glad its not a GM one ...youd be changing it like it a lot more often .
Paul