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Why Does My Lawn Mower Belt Keep Breaking?

A lawn mower is a device used to cut grass on a lawn and trim the edges of a garden. They are also called push mowers, reel mowers, or rotary cutters. They can be powered by either gasoline powered engines or electric motors. 

No matter how you cut your grass, a lawn mower is an essential tool in your garden. There are a variety of types of lawn mowers that range from the hand-operated to motor-driven.

Lawn mowers have stopped working for a lot of people. The issue with most lawn mowers is the belts keep breaking down. If you’re having this problem, then you should know that there are solutions to try and fix it. 

There are a few different solutions that you can try to see if one works for you. Let’s discuss the issue and the possible solutions.

Lawn mower belt problem
Lawn mower belt problem

Reasons why your lawn mower belt keep breaking

The most common cause for the belt to break is too much grass clippings. This can happen after the first use, but it usually happens after a few uses. It is because of wear and tear of various components – pulleys and chains. 

The belt guards are designed in such a way that they keep the metal parts at bay, but they may not work as intended. 

The metal bits will scratch the plastic guards and may eventually wear them down, which will lead to more damage to your belt from the pulleys. The dirt in the pulley groove creates too much friction and decreases the belt’s durability. 

Too much Grass Clippings

Excessive grass clippings on your deck can cause the mower belt to break and in turn, the mower to stop working. It is important that you clean up your deck after every use of your lawn mower or you run the risk of causing damage. 

This problem can be solved by picking up after yourself, getting a deck cover and cleaning off the deck after every use. 

To prevent this, you should use a deck cover after every mower use and follow manufacturer’s instructions on how to clean off your deck.

Improper tension

The belt should have enough tension to stay on the pulleys and deliver power to the blades, but not too much that it causes excessive stress on the belt and the engine. A loose belt can slip off the pulleys or get caught in debris, while a tight belt can overheat or break under pressure.

Faulty Belt Guards

The belt guard is a crucial component of your lawn mower. However, a faulty guard can cause a lot of problems. A faulty belt guard on your lawn mower can cause wear and tear on the belt, and in turn, cause it to break. 

Faulty belt guard is being replacing
Faulty belt guard

In order to keep the belt in working, you may need to remove it from the engine every time. So, it’s important to replace the faulty belt guard or place it if it’s not there.

Wear and Tear of the Belt Pulleys

When your lawnmower belt is breaking, one of the most likely culprits is friction between the pulley and belt. If you are experiencing this issue with your lawn mower, it could be that the pulley rides on bearings are broken. 

The friction created when the blade engages that they wear down over time until they become too worn out to continue functioning properly. 

You should also check for the rust or sharp edges on the pulleys. If you see any of those, solve the problem immediately.


The belt should be aligned with the pulleys and the engine shaft, otherwise it can rub against other parts of the mower or twist and bend in unnatural ways. This can cause damage to the belt and reduce its efficiency.

Low Quality Belts

There are many reasons why you may want to replace your OEM belt on a lawn mower. One of them is because if the belt breaks, it could cause injury or damage to the engine. 

Low quality belt of a lawn mower
Low quality belt

But there are other reasons as well, such as general wear and tear. But if you replace them with low quality aftermarket belts, you might have the problem. 

They don’t stand up to the wear and tear of normal usage very well. Overtime, they will cause you to break your lawn mower belts.

You should use OEM belts every time. They are made of higher quality material and will stand up to the wear and tear.

Dirt in Pulley Grooves

If you own a lawn mower and your belt is wearing down, it is important to know the problem. One such problem might be dirt in the pulley grooves.

Dirty pully of a lawn mower
Dirty pully of a lawn mower

Over time, this causes your belt to be stretched and slip frequently, which will result in greater wear on the belt. This is why it is crucial for users to keep checking the pulley groove and regularly clean them.

The most common problem of lawn mower belts is the wear and tear due to the debris and sand that get stuck in the pulley groove found on a sandy lawn.

Lawn mower belts are designed to be durable and with the weekly upkeep of a sandy lawn, it is no wonder that they wear out quickly. The pulley groove gets filled with sand and debris which can cause the belt to slip and get damaged. 

The debris then gets accumulated in the other components which makes it difficult for it to run smoothly.

The belt is the most important part of your equipment for ensuring you have a safe and enjoyable time on the lawn. The belt should be inspected, and thoroughly cleaned and dried each time to keep it in good condition. 

This can also be done when you change the belt and replace it with a new one.

Tensioner Spring is Weak 

The tensioner spring is the main reason a lawn mower belt can break. The tensioner spring is also responsible for sustaining proper belt tension. 

When the spring breaks, it typically occurs over time as excess friction occurs, causing belt failure.

If you have a broken lawn mower belt, there are four basic steps you can follow to fix it:

  1. Replace the tensioner spring by removing the old one and installing a new one from your local hardware store.
  2. Make sure that your belt is tight enough so that it doesn’t slip and break prematurely
  3. Check to make sure that your blade adjustments are correct so that they don’t cause extra friction

How to Prevent Lawn Mower Belt Breaking

To prevent your lawn mower belt from breaking, you should:

  • Check the belt regularly for signs of wear and tear, such as cracks, frays, cuts, or glazing. Replace the belt if it is damaged or worn out.
  • Adjust the belt tension according to the manufacturer’s instructions. Use a tension gauge or a ruler to measure the deflection of the belt when pressed with moderate force. The ideal deflection is usually between 1/2 inch and 3/4 inch.
  • Align the belt with the pulleys and the engine shaft. Make sure there are no twists or bends in the belt and that it runs smoothly over the pulleys. Use a straight edge or a level to check the alignment of the pulleys and adjust them if needed.
  • Clean the belt and the pulleys regularly with a soft brush or a cloth. Remove any debris that may have accumulated in the belt or between the pulleys. Avoid using water or solvents that may damage the belt material.
  • Store your lawn mower in a dry and cool place when not in use. Avoid exposing your lawn mower to extreme temperatures or humidity that may affect the belt quality.

By following these simple steps, you can keep your lawn mower belt in good condition and avoid frequent breakage. A well-maintained lawn mower belt will ensure optimal performance and efficiency of your mower and save you time and money in the long run.


If your lawn mower belt keeps breaking, it could be because of several reasons. The most common reason is that the belt is too big for your lawn mower, which would cause it to slip from the pulley.

Another reason could be that the blade has been misaligned or is worn out. We’ve discussed the problems and we hope these will help you to find the problem and the solution. If you can’t solve it by yourself, get help from professionals.

You can use the best electric self-propelled lawn mower that will last long and causes less belt problems.

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