Alternator fire

qcfarmer · Mar 13, 2013

About two years ago my wife drove my 450 to work and as she pulled into the parking lot, she noticed smoke coming from under the hood. Turns out the bottom alternator burnt up. I changed both at that time and thought whatever, sh!t happens. This morning, I go to start my truck and notice a squealing sound coming from under the hood. As I get out of the cab I notice smoke so I shut the truck off. The smoke smelt electrical so I popped the hood and found my bottom alternator on fire once again. Bath times it has been the bottom one. Anyone else have this happen? Any ideas why this would happen again?

Viking · Mar 13, 2013

Well coming from industrial background with some electric motor and belts id say the belt could be too tight or at a weird angle that the bearings give out and you in-turn burn out your motor. In this case it is an alternator. If this is it, which my thoughts are, than this is a design flaw.

20007.3L · Mar 13, 2013

take a picture????????????

qcfarmer · Mar 13, 2013

Darn, I was too busy putting out the fire to take a picture. What was weird about this time is it was instant on start up.

Viking · Mar 13, 2013

qcfarmer said:
Darn, I was too busy putting out the fire to take a picture. What was weird about this time is it was instant on start up.

I wonder if you put the upper one in the lower spot and a new one on the upper and log how long, or if, the bottom one goes. Seems like an issue because it is the bottom one again. How long was it before they started on fire?

qcfarmer · Mar 13, 2013

They aren't the same at all. This one was put on in September 2011.

qcfarmer · Mar 13, 2013

20007.3L · Mar 13, 2013

qcfarmer said:
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What the hell did you do! WOW!!!!!!!

qcfarmer · Mar 13, 2013

All I did was start the truck.

Zmann · Mar 13, 2013

the time mine almost lit was due to a loose nut on the positive cable

thanks dealer ! anyway I caught mine in time

you can always loose the second Alt https://www.fleet.ford.com/truckbbas/non-html/Q160.pdf

6.0 p-stroke · Mar 13, 2013

I'm not exactly sure how low they mount the dual alternator on 6.4s but maybe it's getting alot of moisture from snow/rain causing it to short and burn up?

qcfarmer · Mar 13, 2013

Unfortunately all the rebuilders up here are back order on the parts for this particular model so I ordered a new Denso unit... 475 bucks. When you say nut was loose, what nut exactly and why would that cause a fire?

Zmann · Mar 13, 2013

On mine it put the alt into full output intermittently as the cable bounced and made/ broke contact

this was a single alt App but if you look around you see the 6.4 dual having the same comment after an issue like you had

Powerstroke_fan · Mar 13, 2013

I was thinking of a overcharging alternator. Ive seen them overcharge and catch them on fire.

Viking · Mar 13, 2013

Looks like it arced up from being dirty. How far down is the alternator?

qcfarmer · Mar 13, 2013

If you look in the passenger wheel well, right in top of the frame. There is no protection from the front tire splashing crap onto it so I might have to fix that

JEEPSTER401 · Mar 13, 2013

I just pulled one off tonight that burnt up. It melted the black plastic off of the alternator and you could see where it was smoldering between the fins. This one was a dead short inside. It didn't quit glowing red until I pulled the cables on the batteries.

Super08Duty · Mar 13, 2013

Sounds like its shorting out or there's too much resistance through the cables. I burnt up my alt when I relocated my batteries due to too much resistance.