PowerstrokeJoe

This afternoon a friend and I were coming home from the city when my fan belt started squalling really bad accompanied with the brake and battery light. I pulled over thinking the belt had come loose. I tightened the belt and the light went off until the rpm's increased above idle.I could tell the alternator was getting hot so I just disconnected it thinking I would limp it home. Well we made it about another 500 ft and she went up in flames. I managed to get the fire out with two milk shakes we had in the truck. I am assuming the regulator stuck open and it was charging full tilt. What I cant figure is why with no power going to it it caught fire. The alternator is about 6 months old and it was a brand new one not a re man. It just seems odd to me. Has anyone else lost an alternator like that? One thing is for sure. I've got a fire extinguisher in every vehicle now. That was a pretty crappy few seconds.

wyoming9

iTrader: (1)

What vehicle were you driving?? 1 wire alternator ??

Just what did you disconnect ?? On your normal Toyota you need to disconnect the plug to disable alternator output

the B terminal just carries the output to the fuse block.

Well did you also disconnect the belt or does the belt drive everything else like the water pump

If all the wiring was disconnected from the alternator the only way it caught fire is the bearings got so hot something combustible ignited and it went from there.

At this time you might not have been thinking real clear for some reason Fires spook some people

i hope you went with a fire extinguisher that is recharged and checked every year!! most others your Milk Shakes would work better.

It would be nice to know just what happened.

scope103

Sounds sorta like a bearing failure. Start with squealing (either the bearing itself or the belt trying to slip), and since the alternator isn't turning fast enough the brake and alternator light come one. Tightening the belt could have made it worse; the bearing just kept getting hotter until something combustible lit off. (The belt?) A bearing failure wouldn't go away with the alternator disconnected, no matter how you did it.

You could try just turning the alternator now. I'm no fire expert, but I don't think fire from overcharging would seize the bearings by itself. I'm guessing you'll find you can't turn that alternator even with a wrench.

waldo01

I have lost two right after each other they both got so hot that they would glow red never burst into flames but in my case it ended up being a short in my battery between the cell

PowerstrokeJoe

It was my Toyota. It is using the stock alternator off the 3.0. I disconnected both the battery and the plug on the back. I was in able to disconnect the belt because it drives my water pump. I am 99% sure it was something electrical in the alternator went, but I'm not an alternator expert. It still spins very freely, but there is something that rubs a bit inside. The stator really charred. It went from cool to the touch to on fire in literally 500 feet. The belt was fine. It appears as though the varnish on the windings on the stator burnt off. The diode bridge also had the paint burned off it The fire extinguisher is brand new and believe me it will be checked regularly. This truck is my pride and joy. I'm not going to loose it. I'll have to check my battery out. I am going to take the alternator back to the place I bought it tomorrow and have him check it. I'll keep you posted.