Craftsman 917.270723 idler pully assembly

[bkenobi]

I have an old Craftsman lawn tractor that's seen a lot of hours. I've worked on the tractor a bit, but not a lot with the deck. I hit a rock today that caused an odd sound. I thought the blade might be bent slightly or there was a grass buildup on the deck. I continued for a couple minutes to see if the clog would clear. When I noticed sparks coming from the mandrel area, I immediately stopped.

I removed the deck and found that the issue seems to be that the idler arm/brake assembly on the left side of the deck is not disengaging correctly. I think the issue is that the idler arm or one of the arm assemblies was knocked out of position. I think only one side is currently moving the brake pad away when the deck is engaged.

Does anyone have a good picture or schematic of how the deck should be assembled so I can make sure I get the components configured correctly. Also, it appears that the brake pads are pretty toasted. What do people use to replace old pads? Or, do I need to source new arm/pad assemblies?

 

[tomplum]

My guess is that if you are seeing sparks coming from the mandrel pulley, that it is hitting the brake arm. The pulley can hit the brake arm when the rear top plate weldment pulls through the deck. A broken leg on the mandrel can cause a similar effect as belt tension can move the mandrel down where the pulley hits. A worn idler cam can also cause engagement/ disengagement issues- but not the sparks.

 

[bkenobi]

The mandrel, pulley, and even blade were quite warm to the touch on the left side. I believe the issue is the brake not disengaging. The mandrel on both sides seems to spin freely without wobble. I replaced the right mandrel a few years ago but the left still looks good.

 

[mddorange]

If you go here: CRAFTSMAN LAWN TRACTOR Parts | Model 91727723 | Sears PartsDirect and then select "mower deck" you will see an exploded view of the deck and parts.

 

[bkenobi]

I saw that diagram when I did my initial search. It's the same one in my manual, but it doesn't show how the parts mate up. I'll try looking again under an image search to see if someone posted a closeup of the top of the deck I guess.

 

[bkenobi]

I pulled the deck off and cleaned all debris from the top and bottom. I didn't seen any issues with the mandrels and all pulleys appear solid and moving freely. I cleaned and lubed with WD40 to at least make sure everything could move freely (rollers, pivots, etc). I manipulated the idler to both positions and both lever arms engaged/disengaged the brake. Not seeing anything out of the ordinary, I installed some sharp blades and put it all back together.

When I fired it up, I couldn't hear the noise initially. But, after just a few seconds I heard the moan again. I stuck my head over the side and could see some sparks emanating from the edge of the left side pulley. I removed the deck again and found that the left mandrel pulley (153535) has ground a groove in the arm assembly (131845). The groove is probably half way through the raised rib/stiffener.

I'm not sure why there is contact when mounted as it does not have a clearance issue on the ground. I could bend the arm but since it appears straight that seems like a bad idea. Also, I realized that I must have replaced both mandrel assemblies a few years back as both have new looking nuts on them and match. The pulley is original, but the rest of the assembly is new.

 

[bkenobi]

Only one picture seems to have attached.

 

[Coyote machine]

If you grab the pulley pictured, can you move it toward the groove by hand? Is there any wobble in it that you can discern, by comparison to the other pulleys? Could you swap out pulleys and see if the issue follows the 'old' pulley?

 

[bkenobi]

I don't have a backup pulley to swap in. I suppose I could swap left to right. I did try moving all pulleys and they seemed rigid. I'll check again though.

It seed as when I pull up on the bed mounting hook (which is where the brake arm is attached) the gap does close to some degree. I don't know how that could apply when mounted though.

 

[tomplum]

The rear weld of that top plate has pulled from the deck. When you tension up the belt, it pulls the plate out of the deck lifting the brake arms into the pulley. The deck is getting weak there. Weld and reinforce or replace the deck.