Cub Cadet Riding Mower Belt Keeps Coming Off

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If your Cub Cadet mower belt keeps coming off, it might be as a result of a loose or worn belt, worn idler tensioner bracket or spring, defective belt keepers or loose pulleys.

In this article, I share 12 reasons why your Cub Cadet mower belt keeps coming off and troubleshooting steps you can take to diagnose and fix these problems. 

Reasons Your Cub Cadet Mower Belt Keeps Coming Off

Some of the reasons why your Cub Cadet mower belt keeps coming off include:

  • Worn or loose belt
  • Defective pulley bearing
  • Shredded deck belt
  • Belt guide damage
  • Worn spring or tensioner bracket

Tools You Need For This Job

While troubleshooting, you might need to have the following tools nearby:

  • Work gloves
  • Hammer
  • Wooden blocks
  • ⅜-drive ratchet
  • New belt

Cub Cadet Mower Belt Keeps Coming Off: Possible Causes And Fixes

1. Loose or Worn Cub Cadet Belt

A loose or worn Cub Cadet belt could be one of the reasons why your Cub Cadet mower isn’t working well. If it seems loose, it could be that the belt is stretched or worn.


  • Look at the belt and check to be sure that it is tight 
  • If the belt is loose, it indicates that the belt is stretched or worn from normal use.
  • If you notice signs of cracking, or it has a shiny or glazed appearance, it means that you need to replace the worn Cub Cadet belt.


  • Replace worn Cub Cadet mower belt.

How to Replace a Deck Belt on Your Cub Cadet Riding Mower


Here are some steps on how to replace a deck belt on your Cub Cadet riding mower:

Step One: Position Your Mowing machine for Deck Belt Replacement

  • Park the Cub Cadet mower on a level and flat surface. Ensure that you turn off the engine and take off your ignition key before you begin to replace the belt. After that, you need to disconnect the spark plug ignition cable.
  • Put the height level of the deck to the highest setting.
  • Put wooden blocks directly below the deck’s highest setting, underneath the deck’s edge for support and lower the deck onto the blocks.
  • To release the deck from the hangar brackets, you need to pull the J hooks from the left-hand side and then to the right-hand side.
  • Carefully take off the wooden blocks from underneath the mower deck.
  • Pull the click pin out of the front deck hanger rod.

Step Two: Change the Deck Belt of Your Riding Mower

  • Take off the belt keeper rod and remove the belt that is within the engine’s pulley.
  • Position your deck height lever back to its highest setting and turn the front wheels to the left position. Slide your mower deck out from the mower’s right side.
  • Take off the cover of the belt from the outer pulleys.
  • Unfasten your idler spring and take off the bolt and nut that secures the deck’s idler pulley with the belt guide. Use a 3/8-drive ratchet that is located in the square hole of the right idler bracket, to separate the mower’s idler pulleys. Furthermore, you may now take off the left pulley.
  • Change the old mower belt with a new one. Ensure that you get the ideal one for your mower.
  • You need to follow the previous directions in reverse order to reassemble the cutting deck.

Step Three: Reattach Your Mower Deck to the Mowing Machine and Route the Cub Cadet Belt

  • Fasten the bolt and nut that secures the mower deck’s belt keeper with the idler pulley and re-attach your mower’s idler spring.
  • Put the belt covers back on the outer pulleys.
  • Slide the deck back underneath the Cub Cadet lawn mower
  • Make sure that you have the belt routed around the engine pulley and also fasten the belt keeper rod.
  • Put the click pin into the front deck hanger rod.
  • Put your J hooks into the hanger brackets on the right and left sides of your mowing machine.
  • Start your riding mower after reconnecting the spark ignition wire. Ensure that you check for any vibration or noises that can indicate a sign of improper deck belt installation.

2. Faulty Belt Keepers

The belt keepers of your Cub Cadet lawn mower are small rod-shaped posts that sit along the side of the pulleys. They are also responsible for keeping the belt in place.

They can become bent or move out of place due to a slack in them. This can hit the keeper and cause the belt to come off your Cub Cadet mowing machine.


  • If you notice that the belt keeper is bent or is out of place, it indicates that they are damaged.


  • Use a hammer to bend the keeper back into place
  • You can replace the belt keepers if the technique does not work. 

3. Shredded Belt


The shredded or defective Cub Cadet belt can affect the functionality and performance of the mower.

In this situation, the belt will become weak and may break, causing the belt to come off the deck of your lawn mower. It can also shred if the belt is not properly installed.


  • Check the belt edges for signs of shredding and inspect if the belts are rightly routed around the pulleys.
  • If the belt is properly routed, inspect if the part of the belt guide makes contact with the deck belt.
  • If you notice a shiny or smooth spot on the metal, then the belt is shredded.


  • Check your owner’s manual to confirm if the belt is rightly installed.
  • It might be possible to bend some of the brackets to their place. Some brackets can also require a bushing replacement. Brackets that come with bushings may only be available for purchase as a bracket assembly.  In this case, you need to contact a Cub Cadet dealer to help you to find the parts that are ideal for your mower deck model. 
  • Adjust or repair the shredded belt

4. Faulty Bearing in The Spindle Housing

It is also important to check any bad bearing in the spindle housing if the belt keeps coming off.

A defective bearing in the spindle housing can make your cutting deck vibrate when you engage the blades. This vibration can cause the belt of your mowing machine to come off.


  • The first step to take is to get work gloves to shield your hands from the blades’ sharp cutting edges.
  • Rock the blade in an upward and downward position by grabbing hold of each end. While rocking the blade, check for any movement. If you notice a movement or you hear a knocking noise, it indicates that the bearing in the housing may be defective.


  • Replace the bad spindle housing.

5. Worn Idler Tensioner Bracket or Spring 

The function of the tensioner bracket and spring is to hold the pulley in line. It has a pulley on one side. 

If the spring or the idler tensioner bracket is worn, it may cause the belt to come off.


  • Vibration is one of the signs that can show that the worn idler bracket or spring is worn. If you notice this sign, it means that you should replace it.


  • Replace worn idler tensioner bracket or spring. 

6. Bad Bearing in the Pulley

Bad bearings in the pulleys may cause the pulleys not to sit parallel and flat to your Cub Cadet lawn mower deck.

In this situation, the sides of the pulley may be higher than the other. This will make the mower belt not to run properly and can come off the pulley.


  • Rotate each pulley by hand to check for a bad bearing. Move them slowly to be sure that they are turning smoothly.
  • Check if you can hear a noise emanating from the bearing or if you feel any restrictions. If you detect these signs, then the bearing is bad. 


  • Replace the bearing in some pulleys. 
  • If you notice a bad bearing in an idler pulley, replace the entire pulley because it contains a sealed bearing.

7. Rust or Oil on Your Cub Cadet Belt

Rust or oil on the belt can cause it to come off the lawn mower. If oil is left on the belt for an extended time, the belt may swell.

An oil leak may cause oil to get on the belt and can result in belt slippage on the pulleys.

Old brackets and pulleys may develop rust that can get on the deck belt. This causes the belt to crack, dry out or break.


  • Check if the brackets and pulleys are rust-free.
  • A low oil level may indicate that you have an oil leak.


  • Ensure that the brackets and pulleys are rust-free. 
  • Replace rusty pulleys and inspect the oil level before carrying out mowing operations.
  • Replace the mower deck belt once you have fixed the issue of oil and rust.

8. Debris in the Grooves of Your Cub Cadet Pulleys

The grooves in the pulleys collect mud or debris that can cause the belt to come off your lawn mower.

The pulley’s material may also cause the belt to stretch and this will allow it to snap or roll off the pulley.


  • Take a look at the grooves in the pulley and check for items (such as debris and mud) that are stuck in the area.


  • Examine the grooves in the pulley and take off any items that may be stuck in this area.

9. Debris Stuck on the Deck Belt

If your mower deck collects debris, it may cause mobility issues for the tension pulley. If the pulley fails to move, the belt will get affected and may come off.


Check the deck for debris. If the pulley does not move, it indicates that the debris has affected the tension pulley.


Ensure that you keep the deck clean to avoid debris build-up. 

10. Cub Cadet Mower Deck Belt Breaks or Gets Heated Up

This is one of the problems that can be associated with your Cub Cadet lawn mower belt. If the belt breaks, it will come off the mower deck.


  • If you detect unsatisfactory cuts, turn off the engine of your Cub Cadet mower and check the mower deck carefully for any sign of belt breakage.


  • To fix a broken belt, you need to clean your mower deck, adjust the pulleys and replace the belt.

11. Extreme Weather And Temperature Can Cause The Belt To Come Off

Your Cub Cadet mower belt may keep coming off in extreme temperature changes. This issue is very common in very cold climes.

The reason is that the belt loses its shape in cold weather. If you continue to operate the mowing machine with this problem, It will produce cracks on the belt and break it.


  • Check for cracks on the belt to know if the belt is damaged. 


  • Do not operate the mower in extreme temperatures and weather. 
  • Replace the cracked belt with a new one.

12. Loose Pulleys

The belt connects a series of pulleys in the mower deck, which enables the mower blades to engage and spin.

If the pulleys are loose, the entire system would be compromised if the pulleys become loose in their positions.


  • Check the pulleys if they are not loose in their positions
  • Examine other parts of the pulley-belt system. If the parts are damaged or lost over time, it means that the pulleys are loose and the mower belt won’t stay in place.


  • It is advisable to seek the help of a trusted mechanic that can check the Cub Cadet mower for defective or missing rear hanger clip pins and draft rods.

Tips to Extend The Lifespan of Your Cub Cadet Mower Belt

Here are some tips to follow to elongate the life of your Cub Cadet lawn mower belt:

  • Replace damaged belt keepers or brackets.
  • Always clean your Cub Cadet cutting deck after mowing to get rid of debris.
  • Inspect the spindle housings and pulleys for bearing failure at periodical intervals.
  • Keep rust and oil from forming on your belt.


Several factors such as loose or worn belt, shredded belt and debris interference can cause your Cub Cadet mower belt to keep coming off.

Follow the troubleshooting guide and recommended fixes in this article to identify and solve these problems.

It is advisable to seek the help of a technician if the problem persists.