Brand new mower deck belt keeps jumping off

[jpilk99]

I agree with Tomplum that the tensioner pivot might be to lose. When you check for play in the spindle bearings, do so not so much up and down but rather side to side.

Thanks ArlyA, Tomplum and others. It's looking like it's that Pulley Idler on the pivoting tension'ing arm, #52 in the attached image, especially the bearing in the center of it, is/may be the culprit? It wobbles a bit on it's own, and certainly does on that pivoting tension arm (which again I think makes sense that the arm is able to move up & down just a little to accommodate the raising and lowering of the deck. ???). Here's a quick vid: Mower deck 2 - tension idler pulley - YouTube

I believe I need a new #52 pulley idler - don't believe I can just swap that bearing.

I went back and tried to move the spindle pulleys side to side and all three were tight as a bull's ---!

Thoughts? Thank you!

 

[Scook222]

The easiest would be replacing #52. You could probably knock the old bearing out and find on to fit it but most of the time those idler pulleys with bearings are cheap.

 

[jpilk99]

The easiest would be replacing #52. You could probably knock the old bearing out and find on to fit it but most of the time those idler pulleys with bearings are cheap.

Waiting on the new idler pulley - hoping it does the trick. I was able to mow for about 100' before it jumped again (I got a new "Keeper belt idler"). Not able to know where the belt is jumping off from - I"m up top riding. Just so weird that the old belt, which I assume was worn/stretched, did fine...

 

[LittleBill21]

Waiting on the new idler pulley - hoping it does the trick. I was able to mow for about 100' before it jumped again (I got a new "Keeper belt idler"). Not able to know where the belt is jumping off from - I"m up top riding. Just so weird that the old belt, which I assume was worn/stretched, did fine...

put a bag of sand on the seat, engage the blades and watch it throw the belt, are you sure everything is reattached properly? i don't think your tensioner is your issue, mine has similar play

 

[jpilk99]

put a bag of sand on the seat, engage the blades and watch it throw the belt, are you sure everything is reattached properly? i don't think your tensioner is your issue, mine has similar play

I'll give it a try, maybe have my son sit & engage drive --- see if I can see it jump. Good idea.

 

[tomplum]

They will generally jump at that idler, hence why the extra guide is helpful. Dressing the top of the step washer in the arm a tad will remove some of the slop from the arm at the mount. Other factors not addressed could be excessive forward deck pitch or missing deck anti sway bar. If you haven't already, flip the deck and verify that a spindle doesn't have a cracked leg.

 

[jpilk99]

They will generally jump at that idler, hence why the extra guide is helpful. Dressing the top of the step washer in the arm a tad will remove some of the slop from the arm at the mount. Other factors not addressed could be excessive forward deck pitch or missing deck anti sway bar. If you haven't already, flip the deck and verify that a spindle doesn't have a cracked leg.

Thanks Tom - please forgive my ignorance, but, what does "Dressing the top of the step washer in the arm a tad" mean? I'll try the other thing of checking the spindle legs. May also need to adjust the excessive forward pitch.

 

[RalphVa]

Check all the pulleys for dented spots. Had this happen on an old JD walkbehind mower: pulley got bent in just a little bit.

Ralph

 

[jpilk99]

Check all the pulleys for dented spots. Had this happen on an old JD walkbehind mower: pulley got bent in just a little bit.

Ralph

Another great idea, thank you.

I actually found out today that ...I'm an IDIOT. I installed the 3 mower blades UPSIDE DOWN after their last sharpen!!! It was a while ago, and I've been mowing my lawn basically head-butting the grass with the mulching fin on the back of the blade. I am pretty sure I need 3 new blades now as one of them, the mulching fin (as I call it) is really bent back. I'm thinking this may be causing one of the spindles to wobble - out of balance...? I may just buy 3 new spindles while I'm at it as I noticed 2 of them are missing a "ring" at the bottom, right where the blade bolts on. See pics

Tomplum, I did inspect all 3 spindles and found no broken legs. This deck/machine is 8 years old - probably a good time to replace the spindles??

 

[tomplum]

You may have just found the problem! So if you bag, only get the HOP blades. The lift is much better on the OEM. No reason to replace your spindles if the bearings are good. A leg will break if you hit something hard enough. Dressing the step bushing is basically taking a flap disc to shave a few thousandths off the narrow part to make a snugger fit with the tensioner arm.