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Toro 15-44 HXL When I engage the deck drive the belt flies off. It does seem like the belt is very loose when not engaged. It is a new after market belt that is an oem match. Is it possible they sent the wrong belt? Also, the idler pulley seems to be slightly canted forward. The belt rides very high on the pulley and it looks like this is where it is popping off. Any suggestions will be appreciated! Thanks

donjonsone1 said:

Toro 15-44 HXL When I engage the deck drive the belt flies off. It does seem like the belt is very loose when not engaged. It is a new after market belt that is an oem match. Is it possible they sent the wrong belt?

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Been there and did that, its the very reason I only use OEM belts in my shop.

Toro are not normally a belt problem as they use standard profile belts.
First thing did you check the new belt against the old ?
Why did you replace the belt in the first place.
Belts come from the factory in bundles, the wholesalers when make & fit the identifing sleeve.
And yse sometimes the wrong sleeve gets put on a belt so they always get checked.

Now that is an old mower and if the belt it loose when you engage the blades either you have routed it incorrectly or parts are flogged out.
Pull the tension arm off and I will bet the hole is flogged out oval.
The owners manuals tell you to oil them but no one ever does, I give them a good heavy coating of dry lithium grease on every service.

Now double check all the spindles & pulleys.
A little nick in a pulley will throw a belt as will a dud bearing.
Everything should turn freely and QUIETLY.

The tension spring can go weak over time and also cut grooves in the mounting points allowing it to go loose enough to throw a belt.
Then here are all of the pivot points on the deck mounting which can allow too much mal alignment for the belt to run.
When you engage the blades, the deck will twist & move towards the engine again causing excessive slack in the belt.

Check for wear on the pulleys themselves, the V grooves wear allowing the belt to sit deeper in the groove effectively reducing the length of the run , thus the belt runs loose.
On a lot of old mowers I run slightly shorter belts to compensate for wear as mower parts are dear as poison down here.

Now if you have to mow before you have the time to check the deck , or get replacement parts then check the belt run at different height settings.
Where ever the belt run is the straitest, engage the blades there, then move the deck to your usual cutting height.
Just remember this is a work around, not a fix.

I did check as good as possible and there are questionable areas. I am leaving for vacation tomorrow but when I return I will recheck what you pointed out. Thanks for the reply. I am new to this area of mechanics so I will remove the deck again and now with good advice I will at least know what to look for. Thanks again and I will reply when I get a better look at the mechanism!

Try engaging the mower clutch at a low power setting, then advance the throttle to full. I have seen belts jump off when the mower is engaged with the engine running full speed yet have no problem at lower engagement speeds.

I did try that but it didn't work. No matter what I try it flies off. I had a friend watch as I tried engaging at lower speeds but it still came off. I kinda think something is really out of line or I got the wrong belt. He said that for the few seconds it engaged it was really shaking and vibrating up and down. I did notice the spindle for the pulley looked like it was bent forward but I am not sure if it is bent or this is the normal angle. I've worked on mechanics most of my life, but all this is new to me. I will continue with all suggestions and hopefully find the problem. Thanks to all of you for your help. I will keep you posted. It seems like the belt I got is too long or I need new parts. BTW the reason I replaced the origional belt was because it looked frayed, worn out and stretched.

:welcome:

I'm going to move this thread over to our Toro section :smile:

I finally got to work on the deck. My question now is. The spring that tensions the idler pulley, is it supposed to have any tension when the belt is disengaged. It does not have any tension until I engage the belt. The holes for the springs are kinda "egged" more like an oval. Is there supposed to be a bushing in the hole? I just don't know if the spring is supposed to be completey "relaxed" when the deck is not engaged. Thanks in advance!

You have a manual PTO so your belt has to have slack when it is off or the blades would turn all the time.