Help! 1992 E350 Alternator Frustrations
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Help! 1992 E350 Alternator Frustrations
Hi all,
Recent 1992 E350 5.8L buyer, first time poster here. I'll completely puzzled and almost defeated with an alternator problem. It's a bit long-winded, but here's the scoop....
Got the dreaded Ammeter light on start-up one morning. I removed the alternator and had it tested which confirmed it was bad. Bought a new one and installed a new 3G plug, stator wire, and crimp connectors from the alternator wires to the vehicle's permanent wires.
These fixes seemed to work. However, after 50 miles or so, the alternator stopped working. I had it checked at 2 different O'Reillys and they said it was bad (I'm now suspicious of this diagnosis). So, I returned it.
I had the original Motorcraft alternator rebuilt. It "worked" for 12 miles before no longer charging the battery.
I'm now convinced the alternator is not the problem. Only thing I can think of is a wiring issue that gets aggravated when driving. I've read all 3 plug wires need to be "live" upon engine start. I'm not confident they are. The only wiring I haven't replaced is the vehicle's. Is that the next step? Or is there something else I should consider? Thank you for reading and any advice you can pass on.
Recent 1992 E350 5.8L buyer, first time poster here. I'll completely puzzled and almost defeated with an alternator problem. It's a bit long-winded, but here's the scoop....
Got the dreaded Ammeter light on start-up one morning. I removed the alternator and had it tested which confirmed it was bad. Bought a new one and installed a new 3G plug, stator wire, and crimp connectors from the alternator wires to the vehicle's permanent wires.
These fixes seemed to work. However, after 50 miles or so, the alternator stopped working. I had it checked at 2 different O'Reillys and they said it was bad (I'm now suspicious of this diagnosis). So, I returned it.
I had the original Motorcraft alternator rebuilt. It "worked" for 12 miles before no longer charging the battery.
I'm now convinced the alternator is not the problem. Only thing I can think of is a wiring issue that gets aggravated when driving. I've read all 3 plug wires need to be "live" upon engine start. I'm not confident they are. The only wiring I haven't replaced is the vehicle's. Is that the next step? Or is there something else I should consider? Thank you for reading and any advice you can pass on.
More Turbo
Joined: Aug 2017
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From: Tucson
Have you checked the battery? Was the battery totally discharged when you put in the alternator(s)?
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Battery is strong. 12.9 VDC. Any time I've driven it or started it on battery charge alone I've used a battery charger to top it off. I've never used the alternator to charge a flat battery.
New Alternator #1 delivered 13.6 VDC while working
Rebuilt alternator #2 delivers 14.2 VDC
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The only variable I introduced just prior to having these issues was I installed a battery isolator. Nothing I've found online leads me to think the isolator could affect the battery/alternator. BUT, I'm desperate. So could it not just be a coincidence?!?!
More Turbo
Joined: Apr 2014
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From: Central NJ
Yes, I've used a multimeter throughout this whole process.
Battery is strong. 12.9 VDC. Any time I've driven it or started it on battery charge alone I've used a battery charger to top it off. I've never used the alternator to charge a flat battery.
New Alternator #1 delivered 13.6 VDC while working
Rebuilt alternator #2 delivers 14.2 VDC
Battery is strong. 12.9 VDC. Any time I've driven it or started it on battery charge alone I've used a battery charger to top it off. I've never used the alternator to charge a flat battery.
New Alternator #1 delivered 13.6 VDC while working
Rebuilt alternator #2 delivers 14.2 VDC
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The battery is only 3 months old, so I'm fairly confident it's not the root of the problem.
More Turbo
Joined: Aug 2017
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From: Tucson
Was the house battery (or batteries) discharged?
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No, the house battery has never been significantly discharged. It's not under a constant load (fridge, etc.), so it's largely remained full.
Disconnecting the isolator doesn't provide an immediate solution to the issue, by the way. Just trying to connect the dots.
Disconnecting the isolator doesn't provide an immediate solution to the issue, by the way. Just trying to connect the dots.
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Fleet Owner
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FWIW a "good" alternator should provide 14.3 VDC in order to work adequately. There is a small bit of tolerance to that but for the most part 14.3 is the target output voltage.
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Reading in another forum dealing mostly with RV-type converted E-Series battery isolators seem to cause all sorts of problems when wired incorrectly or are defective. Frankly I'd disconnect or remove that device from your charging system and see how that affects failing alternators.
FWIW a "good" alternator should provide 14.3 VDC in order to work adequately. There is a small bit of tolerance to that but for the most part 14.3 is the target output voltage.
FWIW a "good" alternator should provide 14.3 VDC in order to work adequately. There is a small bit of tolerance to that but for the most part 14.3 is the target output voltage.
I figured some voltage was headed to the house battery, which was resulting in a lower reading at the start battery (but maybe that logic is incorrect).
Thanks to all for responding
Mountain Pass
Joined: Aug 2017
Posts: 165
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From: Central PA, USA
Yes, I've used a multimeter throughout this whole process.
Battery is strong. 12.9 VDC. Any time I've driven it or started it on battery charge alone I've used a battery charger to top it off. I've never used the alternator to charge a flat battery.
New Alternator #1 delivered 13.6 VDC while working
Rebuilt alternator #2 delivers 14.2 VDC
Battery is strong. 12.9 VDC. Any time I've driven it or started it on battery charge alone I've used a battery charger to top it off. I've never used the alternator to charge a flat battery.
New Alternator #1 delivered 13.6 VDC while working
Rebuilt alternator #2 delivers 14.2 VDC
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