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.