Truck Repair: accessory drive n14, drive shaft, question thanks

Question
QUESTION: what would cause the accessory drive shaft to break off right behind the pulleys

ANSWER: Could be a number of things I guess. Could have been cracked and the belts pulling against it caused it to break off the bearing in there could have been getting hot and weaken it. Just be sure when you go to replace all that its put in time.

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QUESTION: could a bad vibration dampner break it?

ANSWER: I don't think so but if you suspect it being bad I would definitely change it can bend or break the crankshaft.

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QUESTION: thanks, i just had this motor put in, it was a used motor, the seal was leaking around the shaft after they installed the motor and they said they would fix it this spring, taht was 2 months ago, now they are telling me the only thing that could of caused it is the vibration dampner, i had my doubts, so i suspect they are tring to get out of replacing it for free, thank you so much for the answer!

Answer
For that shaft to break because of the dampner the vibration would have to travel up through the gears off the crankshaft and through the gear on the cam to the accessory drive gear.  Not saying it couldn't happen but ive never heard of that causing it.