I have a 2005 v5o, and the belt keeps breaking I have replaced the belt a few times. I replaced the tensioner that didn’t work so I took it to the mechanic, he said the alternator was seizing up so he replaced the alternator. Then today it broke again. I don’t know what it could be. Any ideas? The mechanic said the bearing were fine when I took it to replace the alternator. The belt didn’t shred it was like it rubbed off on one side until it snapped.

 

what's on the drive belt? for most cars there's a tensioner, an idler pulley (or two) and then the accessory - ie alternator, compressor, ps pump. All of these should be properly aligned and should spin smoothly with no run out. Sounds like something is misaligned (bent bracket from a prior fail?) or one of the other pulleys or accessories needs to be tested/replaced.

 

I'd use a mechanic's stethoscope on the candidate culprits (same list mt6127 gave above). If you hear anything remotely unusual in any of them, there's a good chance you've found the problem.

Otherwise, I can only think that somehow the belt(s) was(were) damaged during installation - or I suppose by someone messing with you. Or, perhaps it was an el cheapo belt sourced from an unknown supplier in some squalid third-world country that builds belts out of cornstalk fibers. ;-)