View Full Version : Lawn tractor throws deck belts

05-10-2009, 07:12 PM
I have an older Craftsman tractor model 944.602200 20hp Kohler Magnum with a 50" deck. For the last few years its had a habit of chewing up the deck belt and throwing it off the pulleys. The 3 blade bearings are tight and the tensioner seems ok. If I take the guard off and run it the belt is bouncing and jumping all over the place. This unit will go through a couple belts a season if not more and throw them off the pulleys I dont know how many times. Am I useing the wrong belts maybe? Im out of ideas.

Hello all and thanks in advance for any input.

05-10-2009, 07:16 PM
maybe try a belt an inch or so shorter to see if it tightens it up some, also check the spring on the tensioner to see if it has been stretched out some.

05-11-2009, 01:36 AM
Ive replaced the spring with a stronger one already. I would think that the belt should be going around smoothly but the tensioner is fluctuating back and forth about an inch or so about 2 times a second. The long stretch of belt going from the right pulley to the left one is just flapping and bouncing like crazy.

Ben's Landscape
05-11-2009, 09:48 PM
I would check your pullies. Maybe one is bent a little that would cause it. Also check your spindles to see if one maybe loose a little. With a belt going that fast it doesn't take much to cause a big wobble and throw a bet. Good luck. Keep us posted.

05-11-2009, 10:42 PM
Sounds like somewhere, either a pulley bearing or a pulley holding arm BUSHING is worn.

Could also be the engine flywheel pulley has lost a key or the C-clip and is wobbling.

But something ain't tight down there, something is loose.

And it could be something stupid like a pine cone or a stick is down there creating havoc.

That, or maybe a pulley has a dent in it.
I'm sure there are some other possibilities, but there is a definite cause for this.

Check e.v.e.r.y.t.h.i.n.g. along the path of that belt.

05-12-2009, 01:35 AM
One thing Ive thought of to try is take the deck off and spin the drive pulley with a 1 horse drill. If it runs smooth the problem is comeing from the engine down. If not its in the deck somewhere. The other is as advised, check the path of the entire belt.