alternator fire

[willgwv]

Almost lost my ride the other day. Driving along minding my own business when I thought that the violinist performing in the concerto had hit quite a sour note. As it went on, I realized that the note was sustaining far too long. I then turned off the radio to find that the note was still playing, getting louder and louder. I pulled over in front of a church and was greeted by billowing smoke from under both sides of the hood and wheel wells. Frantically I jumped out to find flames shooting from my alternator. I used everything I could find to cover it and put it out. Fortunately, I got it out before it burned everything to the ground.

My point is that when I went to the parts store to pick up a new one, when they brought it up on screen, there was a warning that with these alternators there is a tendency for the bearings to freeze if there is not a full range of play in the belt. I assume that that means that the tensioning pulley is fully functional. Mine was. Does this mean that we are all subject to a possible fire due to these alternators.

Hopefully mine will last a few years. But, warning to others. Be careful and listen, and even smell.

Good luck.

[Barney Eaton]

Way too many variables........I have never heard of another catching fire.

GM did have a problem in the '86-'88 time frame (hard to tell when cost reductions kicked-in) with poor cooling within the altenator and the electronics would fry...but not burn. There was a design change that allowed more air flow and later cars have no problem. I had 2 different 1988 GM cars with the 3800 and the original altenator failed.

Also, was your altenator the original part or rebuilt?

[Jim]

I also have never seen one start a fire but I have seen several of them lock up and the belt then slips on the frozen pulley.

[Guest F14CRAZY]

What's there to burn inside the alternator?

[luftweg]

>> What's there to burn inside the alternator? <<

The insulation on the windings and a few of the plastic pieces can burn (mostly melt or smoke)... if it gets hot enough, or a flame is present, the aluminum could possibly melt and burn (ever see underhoood of a burnt car?).

If the bearings lock up, chances are the belt will overheat and break... it's possible anything in the area, that is flammable, might burn or smoke.

[Guest F14CRAZY]

I see. Wasn't doubting if it could happen, but I didn't exactly know what's in the alternator

[Guest Mike_s]

This new years eve I was about 70 miles from home in my 88 (92k), at a stop lite I heard a bit of an odd sound, 20 miles later the dash goes dark, the engine stumbles but picks back up again, the dash comes back on and I start smelling something burning.

While I'm trying to find a place to pull off the road the voltage guage is dropping fast.

Stop the engine and finaly get to open the hood as smoke is starting to come out from under it.

It's the alternator and it's craklin like it's shorting out and the smokes staring to get a little heavier.

I was lucky that a hardware store was across the street so that I could by

a wrench to disconnect the battery and stop the destruction.

While it cooled I bought a new alternator and was back on the road about 1/2 hr later.

The pully on the replacement is about 1/8" less in diameter than the original,

the tensioner did not seem near to bottoming out and the output voltage is

about 13.8 if I recall correctly.

I haven't decided to put on the original pully or not, any comment's on changing the pully or getting another alternator?

[Guest F14CRAZY]

The smaller pulley would cause an underdrive effect, thus spinning the alternator faster.