Lawn Mowers Why am I Breaking Belts on Mower

Published on March 9th, 2015 | by Turner Anderson


Why am I Breaking So Many Belts on My Mower?

A very common question out there is, “Why am I replacing belts every year?”

First you should not be having to replace belts every year or more in one year. Below are some tips on things to look for before replacing that third belt this season.

Common Problems

  • The most common problem with deck belts is excessive grass clipping on the deck. Grass clipping can work there way under pulleys and deck covers which can lead to more serious problems. Make sure to clean off your deck after every use following the manufacturers recommendations.
  • Here a big problem that is missed a lot. You know that guard around that pulley that makes it a pain to take off the belt every time! Well that guard is very essential in keeping the belt in place. Missing belt guards will cause the belt to fly off.
  • Last but not least pulleys can cause big problems. Check pulleys for wear and worn out bearings. If in doubt replace the pulley. Always remember to shut the unit off before attempting any maintenance on the unit. This brings us into the other problem "broken belts".

Jacks receives many calls each day for replacement belts issues, when a customer tells us this belt is the second one this season being replaced this sends up flags.

The biggest issue here is bad pulleys. Check the belt for uneven wear or excessive wear. A pulley rides on bearings that allows it to spin freely. When that pulley does not spin freely friction starts between the pulley and the belt. You guessed it, another broken belt. Remember belts do wear out but if you are replacing the same belt more than you should than fix the problem not the symptom.

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About the Author

is the Internet Marketing Manager at Jack's and the editor of Jack's DIY Center. You'll also find him creating How-To articles, videos, newsletters, and much more.

27 Responses to Why am I Breaking So Many Belts on My Mower?

  1. BOB says:

    Good day . I replaced a broken belt on a LT1042 Cadet today — The replacement Kevlar belt was brand new in a sealed bag , but after installing it , the belt only lasted 15 minutes and broke again …………. Do you have any idea what would cause this

    • bgreen says:

      i had continuous belt breaking problems on my old murray 42 inch, finally pulled the deck off, saw that the problem was the brakes, removed the brakes entirely and also used a shorter belt because i had one on hand, now the blades of course start turning when the motor does but seems no problem and ended the belt breakage and flipping off, it may not be the recommended safety sam fix, but it made a useful mower out of it.

  2. Don Bissette says:

    Make sure the bearings are good and make sure the pulleys are level

  3. Gary says:

    Replaced the belt and the pulleys and the bearings the middle of the summer and about 3 weeks ago the new belt broke again. What may be the reason for this? Could the belt be hitting something as the pulleys pull it around? I thought I heard a slight clicking sound now and then and wonder if that has something to do with the breakage. thanks

  4. Dan M says:

    My Toro Recycler can burn the self propelled belt out on the smallest pieces of mulch. Very frustrating considering I’ve had to repair more than three times over the last 5 years. Is there a mower out there where that issues would not be a problem often?
    Thank you

  5. Billy says:

    The mower belt broke 3 times in 2 mons on my la145 jdeere this spring, the first belt lasted 6 yrs. Well maintained,all ways greased,all spindles turn good, what’s my solution,

  6. jeanette says:

    I’ve replaced my belt on my ariens rider mower 3 times in 8 months model number is 93608300 what could be the probleme

  7. Ryan marrs says:

    I have a new Scag Cheetah. Already broke 2 belts. What could be the problem. Problem.

  8. Mike Huys says:

    I have a Cub Cadet LTX1040 I removed both belt guards and then replaced them . I did this in order to clean the mower really good, but now every time I engage the blade the mower makes a loud thrashing noise. HELP.

  9. Jerry Donaldson says:

    I have a craftsman 48in deck 27hp riding mower and have just started having problems with the belts breaking on it. These belts seem to be shredding on one side. I have taken the mower deck off and checked the pulleys for alignement they all turn freely could it be im buying bad belts. This one belt lasted 2 hrs before it broke please help me on this thank you.

    • Brandon says:

      Check to make sure there aren’t any obstructions (small piece of wood, rocks, etc) in the belt path that it could be rubbing against.

    • Mark says:


      Did you ever figure out what was causing your mower to break the belts after 2 hours? Mine is doing the same thing this year. Thank you for your time. Mark

  10. Shamrock says:

    I have a troy built pony, 42in.deck and every time I mow it shreds the drive belt that runs from the front of the mower pully, to the rear pully before I get done mowing the yard. any idea what the problem could be? those belts are expensive!

    • Don says:

      Did you figure out what is causing the problem of the belts coming off? We have the same problem, we have to buy a new belt with each use. It’s awful. Thank you

    • Janelle says:

      We have had our Troy-bilt TB42 for 2 years now. Since having purchased it in 2015 we have an average belt of once (maybe twice per year as we have a large yard). This mowing season alone we have replaced the belt 5 times, three of which have been in the past week. We went to Lowe’s last night and picked up, yet another new belt. Put it on today, I started to mow, short grass I just mowed last week, as I didn’t want it to get too tall or have the possibility that it would flood again (we live in Missouri, and no we have not been cutting tall grass with the mower, we do that with our farm tractor or a push mower and then go over it with the riding mower.). We have taken the deck off of the lawn tractor once but I’m afraid that I am going to have to replace all the deck pullies as the belts show MASSIVE signs of UNEVEN wear. Any idea as to what is causing this? Were either of you able to find out anything concerning your own issues with your Troy-bilt’s belt issues? It’s just too expensive to pay $40 every time I have to cut the grass…

      I mowed today for a WHOPPING 20 minutes before the belt would no longer stay on the deck…..I can’t keep doing this, it’s illogical and expensive.

  11. Roger & Angie Hejl says:

    I have a john deere 777 zero turn commercial mower that most recently has started breaking the electric pto clutch belt. I have checked the pully bearings and all seem smooth. The replacement belts have come from john deere. If I engage the pto at an idle it kills the engine and if I engage it at a higher idle it seems to be such a harsh engagement. One thing I noticed is that the belt seems to ride so deep in all four of the pulleys.

  12. Harvester says:

    Be sure to always inspect your tensioner spring along with idler pulleys. A weak tensioner spring will allow unit to still operate yet belt have a least bit of slip that can appear almost unnoticeable but will prematurely wear a belt out.

    Certified John Deere Technician

  13. Steve Amelunke says:

    just bought a countyline model 20969 crt tiller, I can not find parts for this tiller , is this tiller listed under another name ?

  14. Jesper says:

    Just had to replace a belt on my snapper elt2246. I had placed the old belt wrong when it sprung off, and within 30 minutes it was stretched beyound recognition. I noticed that the pulley that has to tighten the belt, the one with a spring attached, touched the belt in more than one spot. So I needed to go through the assembly diagrams to make sure the belt was correctly mounted. It was not, so I had to get a New belt. Now everything works as it should.

  15. joe parker says:

    cube cadet / MTD mowers all the same has an issue with there pulleys not lining up and they know that, they haven’t addressed the issue or tried to fix the problem and we just keep on buying them. I had to use washers to line up my pulleys on my cub cadet after that I had no more problems. longer the gape between each pulley the more play and vibration you get in the belt causing it to break down. closer the pulleys less vibration you have in the belt. what I did was I just added an extra pulley in the longer spaces which tightens up the belt causing less break down in the belt and also reduces the vibration in the belt.

  16. Jim says:

    Will installing those “heavy duty blades” cause premature belt failure?

  17. Dov says:

    This is only partly related:

    A little over a month ago my Craftsman 917.203830 T2400 stopped moving, so I sent it to a shop. They said the transaxle drive belt had slipped, broken the transaxle fan, etc. and replaced the parts for almost $300. Last weekend it happened again. They said the same thing happened and wanted to do the same repair. I said no, because I can replace the parts myself for $60 or so. The main question is, why is this happening? I’m not going to replace these two parts every month.

    Anyone have any idea why the belt would slip, break, and break the fan on one of these repeatedly? Thanks.

  18. My 60″ cut Swisher zero turn BREAKS, not wears out DRIVE belts every 10-12 hours it has 340 hours since new. Any ideas?

  19. liam says:

    I have an old Murray yardking, 1995 model replaced belt twice in the last week ,checked pulley, bearings all good, I was mulching in wet condition s would that wear a belt, I mowed for 30 minutes n then stopped. The best had exploded any ideas ?

  20. Wayne Grant says:

    Hi all,
    some good tips are already posted here, but i would like to add one more solution to tearing up belts.
    Look under, at the pulley attached to the motor itself…it could be there. I checked mine after going through belts continuously and found that, that pulley was the problem. I undone the engine mount bolts and placed washers (spacers) between the engine and the chassis to make the pulley line up when ALL belts were in the WORKING position…I havent changed the belts on anything for over 18 months now. Even though these pressed tin ride on mowers are from a factory somewhere, the chassis could be just a little twisted after assembly…
    Hope this is of some help to your problems, doing this certainly fixed mine.


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