reapeated drive belt failures

[IndestructibleYaris]

Originally Posted by Compeer

Never heard of a yari throwing belts.

Serpentine belt problems usually result from one of three causes: a defective belt tensioner; misalignment of a pulley; or, defective bearings in the tensioner, idler, or one of accessories driven by the belt (including the water pump)

This thing doesn't even have a belt tensioner...it is manually tensioned by a hinge bolt and a sweeping slotted bracket that allows you to swing the alternator away and take up slack.

Misalignment of a pulley? There's no way to misalign a pulley. Every single pulley is a critical engine part that is made to tight tolerance.

Defective bearings in the tensioner? You mean alternator?

One of the accessories? You mean either the W.P., Alt., or AC compressor?

It's not the water pump. The pulley drives a shaft which drives an impeller. Not only would you hear the impeller or shaft scraping, but the car would've leaked every drop of coolant before it'd shred a belt from the W.P. bearings being worn out. Every bit of clearance in the bearing is seen by the seals and impeller as well as the pulley.

Originally Posted by remcafee

the yaris belt is very sensitive to tension, because its a very small and skinny belt, you need a special tool to tighten in properly and not just wedge a pry bar to the side of the alternator becuase the alternator will be crooked in alignment with the belt

How? None of this makes any sense. The alternator bolts to the block and a 1/4" thick bracket. Which way are you prying? What makes this car so difficult?

Originally Posted by bronsin

You're right they are tricky to adjust. Too loose and they Squeal. Too tight and there goes the water pump.

Please enlighten me as to how these are tricky to adjust...seems like you know exactly how tight to make them. Squeal=loose. Just right=tighten until not squealing. Am I right?

One of my earlier repairs in my life was rebuilding the alternator around 340k miles and I had to get very familiar with the belt and alternator, and never did I think this job was ever a challenge or a mystery in any way