Belt keeps jumping off the pulleys

[aubrey]

Hi,
I have a 1989 Craftsman Mod. 917.255919 lawn tractor. Problem: The drive/ground belt continually jumps off after stop/ kill the engine and then try to re-start it. Push in the clutch, turn the key and the belt jumps off. I have had it worked on 3 or 4 times (or more) by different repair shops, but no one gets it fixed. Pulleys seem to be good and new belts don't help. Could the back pulleys which aren't perfectly lined up be the problem? or problem in the PTO clutch (which seems to work ok.)
I have removed the mower deck to have a better look but can't figure it out. Aubrey DFW area.

 

[bertsmobile1]

Get the mower up in the air without the deck
MAke sure it is very secure on jack stands.
Get under and have some one go through the proceedure that causes the belt to jump off.
Watch to see where it is escaping from.

Have a good look at the transaxle
Most have 4 mounting bolts on the axle itself then some sort of stabilizing bracket at the front to stop it rolling forward
These entire bracket fall off, or the bolts fall off & I have even seen a couple where the bolts have sheared through.
Some times even a loose bolt will allow the transaxle to tilt forward & toss the belt.

 

[Hammermechanicman]

When the belt comes off look and see which pulley it has come off of. All of the pulleys should have some type of belt guide to keep belt on when clutch pedal is depressed. With the pedal down and parking break set see if you can slip the belt off any of the pulleys. My guess is either as Bert said rear end loose or there is a missing belt guide.

 

[aubrey]

Get the mower up in the air without the deck
MAke sure it is very secure on jack stands.
Get under and have some one go through the proceedure that causes the belt to jump off.
Watch to see where it is escaping from.

Have a good look at the transaxle
Most have 4 mounting bolts on the axle itself then some sort of stabilizing bracket at the front to stop it rolling forward
These entire bracket fall off, or the bolts fall off & I have even seen a couple where the bolts have sheared through.
Some times even a loose bolt will allow the transaxle to tilt forward & toss the belt.

Thank you. That may very well be the problem. I will check it out.

 

[aubrey]

When the belt comes off look and see which pulley it has come off of. All of the pulleys should have some type of belt guide to keep belt on when clutch pedal is depressed. With the pedal down and parking break set see if you can slip the belt off any of the pulleys. My guess is either as Bert said rear end loose or there is a missing belt guide.

The guides seem to be all OK, but will re-check. thanks

 

[bertsmobile1]

I regularly find belt keepers missing.
So it is always worth while to check what is under your mower against what the IPL shows as being there

 

[Alex Geisendorfer]

Hi,
I have a 1989 Craftsman Mod. 917.255919 lawn tractor. Problem: The drive/ground belt continually jumps off after stop/ kill the engine and then try to re-start it. Push in the clutch, turn the key and the belt jumps off. I have had it worked on 3 or 4 times (or more) by different repair shops, but no one gets it fixed. Pulleys seem to be good and new belts don't help. Could the back pulleys which aren't perfectly lined up be the problem? or problem in the PTO clutch (which seems to work ok.)
I have removed the mower deck to have a better look but can't figure it out. Aubrey DFW area.

Those problems can occur if the pulleys are not aliened properly. If you happen to have the original belt that you were using when this problem started to occur, you should take a look and see if you find any uneven belt wear, that would be a sign that your pulleys are not aligned properly. Another suggestion is that your belt might not have enough tension, this could very well lead to the belt slipping off. A key identifier before the belt slips off is if your tractor moves slowly, ( there should be nothing wrong with your engine but the belt won't get enough grip because there is not enough tension. Also try some belt tension fluid, you can't find some at an auto parts store that should allow your belt to get more grip.

 

[GentlemanFahmah]

I had this on my Hydrostatic drive 46" tractor. After a good bit of looking and thinking, I found that the front mounting bolt to the transaxle was snapped off and it then allowed the transaxle to rotate slightly under negative load which popped the belt off. Pull a wheel and look at the two bolts on the transaxle on one side and note if you see small cracks in the frame and mount which indicate the transaxle is twisting. That tells for sure the transaxle is rotating and allowing the belt to mis-align and jump off. This is a common problem in Husqvarna and Craftsman tractors to the point that you can buy a repair kit on Amazon, (https://www.amazon.com/Husqvarna-532437498-Vertical-Frame-Mounting/dp/B00TD3XIZO) but that does not address the front mount if that bolt broke allowing the transaxle to twist.