I have a 96 E150 TMC conversion with 5.8L, dual air, single batt. With 287,000 miles
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Today while driving I started to put down my electric window. When I did I noticed the GPS plugged into the cig lighter dimmed a lot. A few mins later my speedo started jumping all over then maxed out and stayed at 90mph (not electronic instruments, it’s a needle) then I noticed the bat/alt gauge at zero. I got to my job and unhooked the bat cables. During a break I checked the alt wires and noticed one had rubbed through the jacket on the ac box It all appears plastic but maybe aluminum there somewhere. I put a magnet in the area and nothing. Anyway I taped up the wire and finished the day I hooked the battery back up and it started right up but the alt/batt meter was at maybe 10v. When I rev the engine it climbed some so I figured was charging and started driving home. 10 mins later lights dimmed and alt/batt gauge was at zero again. Finally it cut off about 20 miles from home and I am towed back.
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This sounds like an alternator to me since the wire was still in tact I am thinking unrelated but glad I found it now. If it had shorted and blown a fuse or fuseable link I don’t think I would have had made a difference reving the motor.
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Speedo stayed at 90 until about 5 miles into drive home then bounced back to normal then as batt died it just went to zero.
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Does anyone have any suggestions other then the alternator? Confirmation or suspicion about my diagnoses is appreciated. I won’t get to it until sat. night or Sunday and need it Monday so any help is greatly appreciated.
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Dave

 

Sounds like alt to me. All the weird happenings is caused by low voltage.

 

Definately,

that chafed wire or worn brushes.

 

Alt. tested and found no output. New Alt. in and all is fine. However, getting a good new alt was a bit more of a problem. I was ready to leave and decided to ask the parts guy at NAPA to test the new one. First one bad, second one tested good but strange noise, bad bearing I guess. Finally third one was fine and hopefully will stay that way.

Thanks again everyone for your input

 

Good save on trips back and forth plus installations. You did good.

 

I don't know what year Ford stopped putting the Motorcraft 2G into their vans, but it's an filmsy alternator and the "rebuilds" are crap. The 2G is recognized by a plastic plug for the positive output instead of a bolt-down stud.

Motorcraft 3G, however, is not only incredibly powerful but reliable. If you do have a 2G, convert it to a 3G. The housing is slightly larger and you'll have to grind a little bit off the alternator bracket.

 

I have a plastic 3 wire connector and a 1 wire connector plus a stud for the positive output I assume.

As a side note, the 3rd Alt Napa brought me that tested good, died in one day. Tuesday I purchased a new one from another store, and so far so good.

 

Is this the one? Not 2 bolt holes, one on each side of the alt?
I have a "like" for the 3G, I saw a note that this was one of the 3G series in a different case, but what you buy might be an aftermarket with anything inside it. I don't fully understand the market.

Honestly? Go on eBay, look up "ford alternator", make sure you get the right case style, right number of pulley grooves and right pulley diameter, check the guy's feedback, prefer:
"new"
"pulled" (they just had one left over after scrapping a car or whatever,)
"remanufactured" (which might be the same situation as the parts store)
in that order.
Or go to a junkyard!

Or go to a junkyard and get a rebuild kit off of eBay. The diodes, bearings, or slip ring are the likely problem areas. Or voltage reg, which is kind of a separate item anyways. Check the solder joints on the coils.

Get one of the "big amp" ones. Even if you don't need 160+ amps, that thing ain't gonna be breaking a sweat with everything turned on so it'll last basically forever.

Did you charge the batt before putting the new alt in? They say that can kill it... though any alt that can't charge a dead batt is probably a complete piece of crap in the first place and better to find out now than 200 miles from home.

 

Yes I believe that is it. I got the 130 amp. This is my everyday vehicle so I can't wait for an ebay shipment although I would have liked a larger output. but my original 130 amp lasted me 285,000 miles so this should be OK.