Brand new mower deck belt keeps jumping off

[jpilk99]

Hi all.

I have a Husqvarna LGT24K54 and love it. I've had it since brand new and it's 8 years old. Getting ready for this season's mowing/etc., I changed the oil/filter/plugs and decided new belts would be a fine thing to do. The mower Drive belt was working ...okay, but, only for about 10-15 minutes. Once warmed up, I had a hard time getting up hills. So, while under the machine installing the new drive belt, I had the deck out and replaced the Deck belt too. It was working well, but, it looked worn.

Now, when I'm all excited to start cutting the grass, within a second or two of engaging the mower deck, the belt jumps off. I thought it was a freak occurrence the first time, so I put it back on, (yes, routed it properly), and the tension is nice and snug. But still, it jumps. I have both cover mandrells on. I've adopted a process of lifting the deck as high as possible before engaging the drive so as it minimize the likelihood of the belt jumping. (Obviously, the belt is most "in line" with the drive pulley with the deck as high as possible). The belt stays on with the deck up high, but, as soon as I lower the deck, it jumps.

What's strange is that the old, worn, belt was not jumping off. I would have thought, if any deck belt was going to throw itself off it would be an older, worn, ...stretched belt -- not a brand new OEM belt.

I believe the deck's components are in good working order. Spindles, while original, do not have play in them and spin smoothly. Idlers/pulleys seem in good shape - not worn. I will say that one of the cover mandrells had a crack where one of the bolts secured it so it was not TIGHT against the deck. I can't believe that would be the issue. Again, the thing that is strange is that the old belt was not jumping off.

Any ideas? Thank you!

Jay

 

[Scook222]

I have a cub cadet that did the same problem for a while. Make sure none of the idler pulley brackets got bent down. Also if the deck has L shaped metal guards on the idler pulleys, make sure that they line up with the hole on the bracket. On ours it looked like a bubble in the paint, and tightened flush. I eventually took the deck off and took the brackets off and noticed the tab to line up after I cleaned the deck of real good. I have never had a problem since I put the little bubble in the hole.

 

[jpilk99]

Thank you, Scook. Will check those idlers tomorrow!

 

[jpilk99]

I have a cub cadet that did the same problem for a while. Make sure none of the idler pulley brackets got bent down. Also if the deck has L shaped metal guards on the idler pulleys, make sure that they line up with the hole on the bracket. On ours it looked like a bubble in the paint, and tightened flush. I eventually took the deck off and took the brackets off and noticed the tab to line up after I cleaned the deck of real good. I have never had a problem since I put the little bubble in the hole.

I checked the deck and all spindles appear fully in line. I tightened down both cover mandrells. I put the "idler belt keeper" arm/bar back in.... All this resulted in about 5 minutes of use and then the belt jumped again. I'll take the deck off and really tug on the spindles to make sure there's no wear/wobble.

Again, I just don't understand how the old belt was doing very well and now a new one is having problems --- I would've thought it would be the other way around. Any thoughts/suggestions are GREATLY appreciated. Basically can't mow my lawn and the grass is growing fast .

Thank you,

Jay

 

[ArlyA]

Gee, seems like one of your pulleys must be off. Are you sure the spindle bearings are all good?

 

[oosik]

Either something has gotten out of alignment or the new belt is not meant as a replacement for your eight year old mower.

 

[kco]

This likely is not applicable, but I had a similar problem with my Kubota L275DT fan belt. For no reason it would flip upside down causing the engine to overheat. A first it was intermittent but when it got worse I could fix it, start it up, and watch it flip upside down. The belt looked in good condition. I can't remember where I found the answer, it may have been on TBN. The advice was that some of the internal reinforcing cords that run the length of the belt might be broken.

I bought a new belt and it solved the problem. I recall when I bought the new belt that I mentioned it to the parts person and he agreed internal broken cords might be the problem.

If you still have the old belt it may be worth putting it back on and see if it works.

 

[jpilk99]

Thank you everyone. Still not sure what's up. I just took this video - hopefully it will be helpful in figuring what's wrong: IMG 21621 - YouTube .

I do hear/feel a TINY bit of play in the middle pulley. The 2 outer ones have even less 'play' if it's play at all. The Tensioner idlers certainly have more play, especially the one that glides in/out - at the end of the pivot arm, but, I get the impression that is by design; to account for the elevation/lowering of the deck so that it keeps the belt in the drive pulley.

I think the belt is okay, it's OEM Husqvarna, but, ya never know. I may get another one.

 

[tomplum]

Everything is getting some play. Much wear at the tensioner arm pivots? If so, you may wish to replace it. The belt guide is missing on your tensioner pulley though. You didn't say which pulleys seems the launch the belt. Buy a couple of the 532198468 guides. I've done these before to help with problematic ones.

 

[ArlyA]

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.

 

[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.