Lawn Mowers Lawn Mower Belt Reference

Published on February 9th, 2015 | by Jacks

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Lawn Mower Belt Problem Reference Chart

Belts do so much to keep your equipment running smoothly. That’s why it’s important to keep them working in peak condition. Check them regularly to avoid serious problems.

The chart below shows some possible signs of belt problems and solutions. This chart can be used as a general guide and is not meant to be used as the sole source of information on belt problems.

PROBLEM MOST LIKELY CAUSE OTHER POSSIBLE CAUSES
Stack is misplaced Belt squeals or slips.
Sidewall repeatedly worn.
Cracked underside.
Belts rubs the guard Damaged tie band.
Sidewall repeatedly worn.
Cover is worn.
Backside idler Cover is worn. Cracked underside.
Improper storage, stored too long Cracked underside.
Sidewall repeatedly worn.
 
Not enough tension Belts excessively vibrate.
Belts comes off pulley.
Sidewall repeatedly worn.
Belts or squeals or slips.
Improper installation of pulley   Wobbling pulley.
Bushings are cracked.
Too much tension Belts excessively vibrate.
Repeated breakage.
Hot bearings.
Shaft bends.
Pulleys are misaligned Belts excessively vibrate.
Damaged tie band.
Sidewall repeatedly worn.
 
Pulleys are damaged Hot bearings.
Wobbling pulley.
Cracked underside.
Belts excessively vibrate.
Bushings are cracked.
Shaft bends.
Belts bottom out.
Damaged tie band.
Belt squeals or slips.
Too much heat Sidewall repeatedly worn. Cracked underside.
Bearing too far from pulley Hot bearings.
Shaft bends.
 
Poor bearing or shaft worn Hot bearings.
Wobbling pulley.
Shaft bends.
 
Belt has reached end of service life Belts bottomout.  
Belts matched up wrong Belts excessively vibrate.
Sidewall repeatedly worn.
 
Wrong type of belt Belt rides too high.
Belts bottom out.
Belts squeals or slips.
Belt comes off pulley.
 
Machine induced impulse Repeated breakage. Belts excessively vibrate.
Belt comes off pulley.
Too much oil or grease Belt swells, is soft.
Hot bearings.
Belt squeals or slips.
Sidewall repeatedly worn.
 
Harsh operating conditions Sidewall repeatedly worn.  
Grooves of pulley dirty (particles in them) Cracked underside.
Belt comes off pulley.
Repeated breakage.
 
Too much moisture Belt comes off pulley.
Repeated breakage.
 
Insufficient belt on small pulley Belt comes off pulley. Cover splits.

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About the Author

Jack's Small Engines has been providing parts for outdoor power equipment online since 1997. We also run a service center for outdoor power equipment like riding mowers, snow blowers, generators, chainsaws, and just about anything else.





7 Responses to Lawn Mower Belt Problem Reference Chart

  1. Mark says:

    Thanks for the reference guide. My white lawn tractor started shaking. Turned out the belt had a flat spot.

  2. Ron Carpenter says:

    installed 2 new belts and riding lawn mower still squeels..

  3. Michael Teets says:

    I have a Toro 30698 commercial walk-behind mower with 3 blades and, thus, 3 spindles. I cut grass every 5-7 days on a ½-acre yard. I have replaced 2 of the blade spindles so far, and am wondering if would be reasonable to consider replacing only the bearings and if this is a DIY homeowner job. I have a reasonable number of tools, as I do most of my own automobile repairs and maintenance. I don’t think any of the spindles is currently bad, but just figured that it’s only a matter of time until one needs repaired or replaced. I’m just wondering what your opinion is about repair vs. replacement of a blade spindle.

  4. RJ says:

    Replace your spindles with spindles that have grease fittings and give them a grease job a couple times a season and you should be ok.
    I had a spindle that didn’t have a grease fitting so I drilled the proper size hole for a fitting and screwed it in. Now I can keep those bearings greased.

  5. Bill Von Ord says:

    I have a King Kutter 5′ finish mower. Lately, the belts are messing up. There looks to be like diagonal cuts in the bottom of the belt as well as pealing of the outer cover on the belt. This is the second new belt I have had to put on. All pulleys are fine. No wobble or sharp edges. All pulleys are within 1/16 of an inch in uniform height. I mow 23 acres with it. I used to mow for 3 years before changing a belt but now it seems I can not even finish a mowing before the belt is deteriorating now. I have taken some pictures of the belts. I have one more new belt. This mower is about 10 years old and has been a good one. Any ideas as to why the belts look like they have been cut? There are some diagonal marks that have yet to open up but they are like the cut marks on the belt. All pulleys are clear of any debris.

    • Bill Von Ord says:

      I put the other new belt on and mowed the 23 acres. This new belt has done the same thing! Not as bad yet tho. I took the belt off and inspected it. I find that the inner rubber is cracking and breaking under the outer cover! I do not have the belt over tightened either. All pulleys are good. I can not figure this out! Did I get a batch of bad or old belts? Can belts have a shelf life that exceeds their elasticity to stretch?

  6. Jim says:

    My Jacobsen/Bobcat Fastcat ES (742281) zero turn mower has shredded the pto belt 4 times in 3 months. I’ve replaced all of the pulleys, shafts/bolts and bushings and the tensioner spring….except for the components that comprise the drive pulley that is part of the center blade assembly. There doesn’t appear to be any slop in the pulleys or shafts and the tensioner appears to be applying a correct amount of tension…visually the same as the picture in the owner’s manual. Still, when the pto is engaged to mow, with a brand new belt, there’s excessive vibration in the belt….it visually snaps in and out and there’s excessive and loud vibration. Could the electric clutch be he culprit? I don’t know how it works and it’s too expensive to replace on a whim. Please advise.

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