Deck belt keeps slipping off 2013 Pony

[Jeff61]

I put on a Stens 265-201 deck belt for my Pony model 13WN77KS011. Even if I move the PTO handle slowly, the belt slips off. The spindle guards are in place. The idler pulleys are aligned.
With the mower off and PTO lever disengaged, the belt looks like this on the main pulley:
There is no adjustment that I can see to put tension on the belt when the PTO is not engaged. I'm thinking the PTO cable is stretched and could be replaced?

 

[StarTech]

But is the engine pulley belt retainer in place?

 

[Jeff61]

Yes. It's not shown in the picture because I removed the deck to straighten out the belt.

 

[StarTech]

Then verify the OC of the belt is 96-1/2". On rare occasions Stens can ship the wrong belt in the correct sleeve.

 

[SeniorCitizen]

The belt in the pic looks way too loose . I believe you have the wrong belt . Why is the sheave in the pic so rusty ?

 

[Scrubcadet10]

is it routed around the pulleys correctly?

 

[bertsmobile1]

The $ 10,000 question
How far is the belt keeper away from the pulley ?
The gap should be no more than 1/4"
The belt should be able to come away from the pulley far enough not to actually touch the pulley .
If it does touch the pulley then the belt can end up being burned by the pulley rubbing against it when the engine is on & he blades are off .
Does the belt actually drop below the pulley bottom rim so when you engage the blades it jumps strait off ?
Are the engine pulley belt retainers in the correct place
Around 2 of 3 that I service the belt retainers are way too far away from the pulley and usually bent too far back

 

[StarTech]

Now there is a couple possible here one is the belt is too long which I suspect and the other is the brake shoe on the moving idler is severely worn or is completely missing. Also spindle pulleys wear is in there too. It might take dropping down to a 95-1/2" or 96" belt as the current belt appears to be about an inch too long.

 

[Jeff61]

is it routed around the pulleys correctly?
View attachment 66823

Yes. I think it has to do with too much slack with PTO off. Seems like there should be an adjustment for the PTO cable like on John Deere decks, but I can't find one.

 

[StarTech]

Just ran across a Huskee with same deck. Another had changes the idler pulleys out ones that were 4" across the flats [Rotary 9377]. Boy was the original belt so loose. They were putting a 95-1/2" Polyester which of course doesn't last long as a deck belt. I change the pulley to 4-1/4 pulleys [Stens 280-646] and the belt was as good as it should be except at the lowest deck height. It was a little to loose then I replaced the PTO handle bushing and now it is fine.

Just shows you how just quarter inch in pulley diameter can really make a big difference.

BTW the mower came in with several other problems but the deck problem was create recently when the owner had to buy a new and was given an after market 144959 Polyester belt that wasn't 95-1/2 but instead is 94-1/2. This also shows that you must measure the OC even on new belts as they can be wrong even when the belts are labeled correctly. No wonder he couldn't fully disengage the deck.