Since I bought my 1995 f250 last year, the micro-v belt was inclined to come off at high rpm. This damaged multiple belts and was a source of annoyance and some expense as micro-v belts aren't cheap. I knew that it must be caused by a misaligned pulley, but at a glance they all seemed close (I'm accustomed to v-belts -- if you're within an inch, you're close enough ).

Finally the aggravation was too much and I decided that I had to fix it. I put a straight edge on the harmonic balancer and discovered that the alternator was indeed .25" rearward from being aligned. The other pulleys were properly aligned. I removed the alternator and the alternator / smog pump bracket to see if there was enough play to move the bracket forward but there was not. The bracket appeared to be original. It's cast aluminum and there's no way it was bent or anything. All seemed right with the harmonic balancer as it lined up nicely with the other pulleys.

My solution was to "machine" .25" from either the bracket or the alternator; thereby moving the alternator forward the necessary distance. I opted to grind down the alternator ears, as I didn't want to weaken the aluminum bracket. This done, I bolted it all back up and tweaked it with shims till it was lined up just right. This seems to have completely fixed the problem; I can let the ol' 300 scream and the belt stays on.



So my question is, have any of you folks seen this before? Thanks

 

Soimething is wrong with your mounting setup or your alternator,send pictures of how you have yours mounted. heres pics of mine to show what it should look like.

 

Here's the pics. You will notice that the bottom bolt on the alternator is going the opposite direction from the original. This is because I don't have a smog pump and when I have my other belt on (for my snow plow pump), it is routed differently and the head of that bolt is in the way.

BTW that alternator is brand new (the old one had been charging low for some time, so I decided to swap it while I was fuddering around with it). The old one, which was a lower amperage unit and had the upper ear in a different location, was misaligned just the same as the new one.

 

You have the alternator lower ear in the wrong spot!! You have to use the outer one!

You use the outer two holesfro the high amp 130 amp 3g, and then you use the inner 2 for the 95amp 3g!!!

Your using the outer top hole, yes proper! If you just had put your alternator in the right part of the bracket on the bottom it would have fit properly!!!
BUT YOU piqued my interest when you said plow pump. I would like to see this pump and your engine bay to a greater extent, please message me or made a thread about 4.9 snow plow pump on serpentine setup, because its obviously not important here but I NEED TO SEEIT !

 

The lower alternator bolt is indeed through the outer hole. My previous alternator was the lower output model and used the inner hole as you stated. However, the higher output version will not even line up to the inner hole.

I will post some pics of the plow pump and engine bay soon.

 

My bad I was wrong, I dont use that hole either. its for the smog pump as you said. my bad lol

 

The alternator bracket has 4 holes for the alternator, as you stated. The inner two are for the 95 amp alternator (this is what my previous alternator was) and the outer two are for the 130 Amp alternator (this is what my current alternator is). The other hole that you see is for the upper bolt on the smog pump (which I have removed).