Why would my alternator belt keep snapping?

Okay this is gonna be a little long,but I really want to cover all the bases. A few months back my 1999 Nissan frontier needed the starter changed so I had some guy who was referred to us by a friend come over and change out the starter. He changed out the starter and the truck started right up so I paid him and he left. I then took the truck for a drive and not even a mile down the road I heard a belt snap and the truck started to overheat. I then brought the truck to a shop and they replaced the alternator belt. After about five miles of driving the belt snapped again. I brought the truck back and they replaced the belt again saying they must have tightened it too much. After about 60 miles this belt then snapped. Obviously there is something going on to make this belt snap 3 times. Does anyone have any clue what it could be. Did this original guy who worked on my truck screw something up? Thanks alot.
Why would my alternator belt keep snapping?
The bearings are bad on one of the accessories (ie alternator, A/C compressor, water pump, etc.). The best way to find the bad one is to remove the belt and turn the pulleys. They should turn freely with no noise or friction.
Why would my alternator belt keep snapping?
pulley locked up or mis alignment



more likey you had a problem before it snap the first time

the starter wouldnt have a thing to do with a belt

pulleys would belt tensioner pulley maybe locked up

one of the other idler pulley mayb e be bad
It's not the guy who did the starters fault. I would suggest looking at the idler pulley and any other pulleys that the alternator belt rides on for nicks or anything that the belt could rub on. Have the shop also check for bad bearings in anything the belt drives. Good luck
kelly and frankie has good answers worth checking out, Also check out the alignment of the pulleys
Defective - alternator bearing(s), idler pulley bearing, water pump bearing, and or



Get this - A moderately discharged battery OR a defective battery that requires constant charging, will put a demand on the alternator that it is NOT designed for and puts a constant stress on the belt.



Check the battery. Need charging? DO NOT charge it with the vehicle, (takes 100 to 150 miles) - use a portable, automatic charger, (2 to 4 hours).



Defective battery - replace it.
Sounds like one of the pulleys aren't free or nearly seized try each one or just oil them all and try again. Alternators are best as they suck in a load of crap when cooling and the bearings get clogged up.