I have had this problem for some time. My mustang keeps breaking belts. It has been through 3 in a year. I have replaced the brackets and the spacer and the altenator. It looks to be aligned and I am completly stumped. Anyone have any ideas? it is possible that the head could be made for a different altenator setup? Meaning I would need non-stock brackets?

 

Where are you buying your belts from? Is their any movement of the belt when the car is running?

 

it could be as simple as you putting the belts on too tight,and over time they stretch from the heat and tension, than cool down...etc The tension on the belt should be snug, you can do a quik check if its too loose, grab the alt fan (with the car turned off) and try to turn it. If you can move it, its too loose, if not it should be just right

 

The belts are from Oriley's and there is not movement in the belt when running.



I do the same tension test as you mentioned there. (Spinning the fan) Getting it just tight enough the fan wont turn. However, over time say 200 to 300 miles or so the belt will stretch enough that it begins to squeel on startup and can be spun by hand. It is the retightening that seems to do them in because each time it stretches a little further untill it snaps.

 

When you say breaking belts, are you talking about popping off, or are they wearing out ? Also, are you using a ribbed belt? Ribbed belts tend to come off at higher rpms. If this is your problem, switch to a non-ribbed belt and this will stop happening. I had this problem on a 69 Firebird, it was driving me crazy, when I switched to a non-ribbed belt and it never came off again. Alot of racers have had this happen to them and they will all tell you to use a non-ribbed belt. Sorry Goodyear! I had to go with an off-brand. Napa might be able to help you. I hope this helps, I could be way off base.

 

there is such a thing as putting too much tension on a belt too... If you grab the belt with your thumb and forefinger, and move it up and down, there should be no less than 1/4" play and no more than a 3/8" play. Not enough and you're over tensioning the belt. Just as bad as under tensioning.

 

The belts are breaking not just slipping off. I thought i might have gotten the 1st to tight so the next one I gradually tightened untill the alt fan would no longer spin. On the latest one I barrowed a tension tester even. It hasnt broke but has already loosened a fair amount. I have tried both ribbed (for her pleasure =)) and non ribbed. I did notice that the pulley on the alt might be a hair smaller then the other 2 pulleys. The belt doesnt seem the fit as far into it. IT is a small amount though.

 

If it was to tight, you would likely be smoking bearings before the belt gave out.(water pump, alt.) I would be re-checking my pulley algn. and looking for burs or anything that could cut the belt, also, make shure nothing else is interfearing with the belt.( like a bolt sticking out to far) Do all your pulleys spin freely? Is there any play in them?

 

There isnt any play in the pulleys, and it doesnt seem to wear the belt. There is never any grooves or anything like that. The last one that broke looked brand new still except it was ripped in half.

 

Belts are not like rubber bands, they don't just snap, it's coming off first and then getting cut, something on the engine is catching it, or someone doesn't like you.