Bolens st160 lawn tractor, belt won't stay on.

Hi.
I have a older Bolens lawn tractor that I purchase at a garage sale. Its a ST160 model and it has a very large belt that runs the mower deck. The problem is that the belt comes off the pulleys after running a few minutes. It has about seven pulleys on the deck and the belt is about 105 inches. I replace the belt with a new one and adjusted the tension as much as I could on the pulleys. The belt stayed on for about 15-20 minutes this time and then came off again.
I could really use some help.

Carl

 

Are the pulleys all lined up properly?

 

I just went through this same issue on an older Bolans. Belt was 1/2" by 160" which means everything has to line up perfectly or it's not going to stay on. Best thing to do is pull the deck off the tractor and start by checking that all pullleys are tight and that the 3 blade drive pulleys are the same height off the deck. Also be sure that all of the belt guides are adjusted properly. IE. not rubbing on the belt but also not so loose that the belt can come off the pulley. If you have any loose idler pulleys they made need replacement. With a belt of this length any misalignment or wear in the system is going to cause your problem. It takes a bit of time to go through this process but pays off when you don't have to lay out in the yard and put the belt on several times while you are trying to get the mowing done.
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