Deck belt keeps breaking, need some help.

Discussion in 'Lawn Mowing' started by Tlvoskamp, Jul 31, 2008.

  1. Tlvoskamp

    Tlvoskamp LawnSite Member
    Messages: 48

    I have an exmark phazer and it has about 140 hours on it. The first 120 hours went smoothly and a few weeks ago the deck belt started to jump off the pulleys whenever I would engage the PTO. After a while my belt just broke. I went and got another couple of belts and and the dealer instaled an update on the idler pulley that was supposed to keep it from jumping the pulleys when engaging the PTO. So all was going well and last week I was mowing and all of a sudden the belt just blew up, no wear signs anywhere, it just snapped in half. This had the dealer and I both stumped. Today I had another bad experience, the deck belt just split. My current thoughts are maybe there is some burr or something on one of the pulleys and maybe that is causing the problem. This idea does not seem to match up with the broken belts, there is no signs of wear, just failure at one point. My current thought is that I just got into a bad batch of belts that are flawed. Any advice? Any thoughts? Any recommendations on a aftermarket belt. Thanks in advance for your time.

    Travis Voskamp
  2. Cashio13

    Cashio13 LawnSite Member
    Messages: 111

    finally someone with this problem...i thought i was the only one, hahaha. I have a Husqvarna 36" and all was fine for the season until a couple days ago when the belt jumped off twice in a half hour. Obviously i was pissed so i took it to the shop and upon further inspection a mechanic noticed that the belt was actually too long, causing the pulleys to hit, causing it to jump off/break. To fix this we measured the belt, went to Napa (yes the auto parts store) and got one that was an inch smaller. This completely fixed the problem and finally my mower is back to normal. (knock on wood) So i would say do the same. the belt was probably stretched when it was measured so try a smaller one. Good luck, let me know if that fixes it for you.
  3. Tlvoskamp

    Tlvoskamp LawnSite Member
    Messages: 48

    Thanks for the input
  4. brownrog

    brownrog LawnSite Member
    Messages: 3

    I had the same problem on one of my gravely deck belts. This belt runs in some really sharp turns and even bends backward 180 degrees. The original belt ran 200 hours and i replaced it with a NAPA commercial V-belt. I thought a commercial grade belt would be great (wrong). The commercial belts were not lasting long at all. In about 30 hours this particular belt was badly cracked and ready to break. The NAPA manager told me about a lawn mower line of belts he sold called "Blade Runner". I remembered earlier that he told me he had this line but i stupidly thought a lawn mower line would be a cheaper belt than the NAPA commercial belts, Wrong again. He explained that a lot of mowers had a lot of sharp bends and twists and that this belt was a lot more flexible than a V-belt that usually runs fairly straight. Sure enough he was right.These belts were very flexible while the commercial were very stiff. It looks like the blade runner belts are going to do the job. I have already passed 30 hours and the particulary troublesome belt still looks like new. The commercial belts seem to be fine in other position where they run straight lines. I hope this helps someone else, I surely learned a lesson from this.
  5. JimQ

    JimQ LawnSite Bronze Member
    Messages: 1,139

    Check with a dealer. Depending on how old your machine is, there is an idler update kit. It adds an addition idler and relocates others. It's intended to increase belt life. Newer machines leave the factory with the new idler configuration.

  6. JimQ

    JimQ LawnSite Bronze Member
    Messages: 1,139

  7. TomberLawn

    TomberLawn LawnSite Bronze Member
    Messages: 1,299

    I had about the same problem with my Ferris. I had a belt break when I turned on the blades. I mean, the blades hadn't even started turning, the belt just slung off as soon as I pulled the PTO switch. I went to a couple mower dealers nearby and they didn't have a belt long enough (goes around the engine pulley and the whole deck, no jackshaft). I ordered 2 belts from NAPA. Ran one of them for about an hour, things were fine. Went to the next yard, started mowing and a few minutes later, the belt slings off and knots up under the mower. A local master mower mechanic told me the same thing brownrog learned, that the commercial/industrial belts were made to stay pretty straight, like running a huge fan from a motor. That's why the NAPA belt slung off, but I still didn't know why the other one broke. Well, I finally got a Ferris original belt and worked fine. But a couple months later, it broke suddenly also. I put a NAPA belt on to finish the yard and went and got another Ferris belt. These things ain't cheap. I still have the NAPA belt on my mower and the Ferris belt is in the truck as a spare for now. The NAPA belt has been on there for a few weeks now with no problem though, so I'll leave it as long as it lasts. The next belt I get will probably be from Dalco, or however it's spelled. They sell bearings, pulleys, belts, and stuff like that and I've heard they're pretty good.
  8. Big Wes

    Big Wes LawnSite Member
    Messages: 248

    Check your belt guides and make sure they 're in the correct position. Belt guides are bolts / rods that are attached to the deck close to the pulleys to prevent the belt from jumping off. Just a suggestion.

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