Belt coming off Poulan riding mower

MarshMarlowe

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Poulan Pro 300EX Lawn Tractor 42" Deck


I recently replaced the belt on my mower. I can mow with it for a while, but the belt eventually comes off. I can put it back on and continue mowing for a while, but it will come off again. The clutch engagement spring cable is on a sliding mount. I slid the mount further back to tighten the spring a little bit, and that seemed to help, but the belt still comes off.

I pulled the deck out to replace the cable, and I checked that all the pulleys spin freely. Could it be that the pulley engagement spring has gotten loose somehow? Or would a shorter belt help? All the hangers and belt keepers appear to be in place

Thanks for any help
 

bertsmobile1

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Which belt, brand and number did you fit ?
Did you check all of the pulleys for flat spots or bearing problems ?
Does yours have the upgraded cable which fits on top of a protruding bolt on the tensioning pulley ?
 

MarshMarlowe

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This is the belt I replaced the old belt with (the old belt was also slipping off)

Amazon.com : 1/2" X 101" Pix Kevlar Corded Belt, Use For Craftsman Poulan Husqvarna 429636, 197253...Also John Deere M84136, M87323 : Lawn Mower Belts : Patio, Lawn & Garden

I didn't see any flat spots on the pulleys when I pulled the deck out. All the pulleys spin freely with no resistance, but I'm not sure what a bearing problem looks like. I will say the deck is noisy when it's engaged, but I was assuming that noise was just rattling attachment points (hitch pins / washers etc)

Does yours have the upgraded cable which fits on top of a protruding bolt on the tensioning pulley ?

I'm not sure what you're referring to, but here's a picture of the deck engagement cable

 

bertsmobile1

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pictures tell 1000 words.
That is the old cable which locates into a hole in the tensioner arm.
The upgraded system mounts the spring to an entended mouning bolt for the tensioning pulley.
From the photo it looks very much like the tensioning arm is bent down towards the deck.
This AFAIK is one of the reasons for the upgrade.
Check the hole the spring goes into for elongation.
Remove the tension arm and check the pivot hole for elongation.
While it is off flatten the tensioning arm the tensioning pulley should be aligned with all the others otherwise the belt will run up and over the lip at the slightest provocation.
 

MarshMarlowe

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So, I got to looking at the deck diagram, and turns out I was wrong about having all the belt keepers. I'm missing 2 belt keepers here -

150e60f6-d572-4d45-8e31-0e9ddffd629e.jpg


I'm thinking now that those missing keepers are most likely causing my belt to slip off

From the photo it looks very much like the tensioning arm is bent down towards the deck.

Yeah... it is bent down... because I bent it down. When I pulled the deck, it looked like that arm would ride the belt, so I pushed it down. Bad idea, eh?
 

mechanic mark

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Idler pulleys have bearings located in center of pulley that mount bolt fits through. In order to check idler bearings properly, pulleys need to be removed. Hold pulley in one hand & spin bearing with opposite index finger, a good bearing will spin smoothly & a bad bearing will be rough when turning. If bearing does not spin smooth, replace complete idler pulley, comes with new bearing installed.
 

bertsmobile1

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Very bad idea.
You can see the belt is ready to leap off it.
If anything it should be slightly up to guide the belt from the deck to the engine pulley which will be out of the plane of all the other pulleys,
Both of the idlers must have a keeper.
The best place for it is at the tanget point from the strait line from the engine pulley
 

MarshMarlowe

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Thanks for the help Mark and Berts. I have the belt keepers on order, and I will see about straightening the rod out. Hopefully I will get it sorted out
 
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