Mazda: alternator belt, excessive tension, miatas

Question
I know your expertise is in Miatas, but hopefully you can help us with our Protege.  We have replaced the alternator belt in our 1993 Protege 3 times in the past 10 months.  And it has just broken again! Our mechanics have no idea why it keeps breaking.  The last time they replaced it (Spring 2001) they said they tightened up some things. (I'm sorry I don't know excatly what they tightened.)  This time the belt has lasted longer.  The other times it only lasted for at the most 2 weeks.  We are getting very frustrated with this problem, and would welcome any ideas or suggestions as to what is wrong with this car.  Thank you.
Kelly Newport

Answer
Hi Kelly-
very strange problem indeed. The only factors I can think of to make a new belt fail are excessive tension (set too tight), excessive heat that breaks down the belt, misalignment that would wear the belt down from the edges in and cause a lot of heat, a damaged pulley surface that would cut the belt, or finally if some other shroud or cover is rubbing on the belt.
I guess it would be helpful to see what the belt looked like at failure - whether it had severe edge wear or not.
Hope this helps-
JB