Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Normally when I belt comes off it is due to belt is stretched. It will come off by idler pulley due to only the back side rides on the idler pulley. I would dbl check all pulleys and make sure none are bent downwards
What is the full model number? Need to identify your deck. With most decks, each pulley has a belt guide, that keeps belt in place, I suspect you have a belt guide missing or out of position, so the belt walks off. Are all guides in place and close enough to the pulley so the belt cam't get out?
4 and 50 are two belt guides. Which pulley seems to be the one letting belt get off?
# ***** is the spring that has to keep the belt tight. The idler bracket in the first link, # ***** can be adjusted to tighten the belt if more tension is needed.
# ***** is bracket that has t keep belt in place on the left pulley. Is it there, and is it close to the pulley? It can be bent , letting the belt slip out.
It has to be close enough to the pulley that the belt can't slip out!
Is belt distorted? If belt is not nice and flat, it will never stay on. Have you tried a new belt.