Having to keep putting your Exmark belt back on your mower can get frustrating. Worse yet, when your mower belt continues to break, you incur the expense of having to keep buying new mower belts.

It’s important to find the root cause of your belt problem so you don’t have to keep dealing with your Exmark belt continuing to come off your mower.

An Exmark belt can come off or break when a belt is worn or damaged; a bearing is bad in your pulley or spindle housing; a deck bracket has failed, or debris is causing interference with components on your Exmark deck.

I have share items below that can cause your belt to come off your Exmark and how to repair the problem.

Reasons Your Exmark Mower Belt Keeps Coming Off or Breaking

Worn and Loose Exmark Belt

Your Exmark belt can become loose over time from normal use. When your belt doesn’t sit tight around your pulleys, it can come off. You must replace a worn belt.

A shiny glazed appearance on your belt, one that sits deep into the grooves of the pulley, or a belt that is stretched are signs your belt is worn.

Shredded Exmark Belt

While you were checking your belt to determine if it is sitting tight on your pulleys, you may have noticed shredding on the edges of the belt. This is normally a result of your belt rubbing against a bracket. Identify the bracket that is causing the belt to shred.

A good indication of which bracket is the problem is the one that has a smooth shiny spot on it from rubbing.

Once you find the bracket that is causing your Exmark belt to shred, you can try to adjust the bracket into place so it no longer rubs on the belt. Check bushings that may be in your Exmark brackets and replace them if they are bad.

You will find you have the option to change out the bushing on some brackets but will have to replace the whole bracket assembly on others.

Bad Bearings in Your Exmark Pulleys

When your pulleys are not sitting flat and parallel to your Exmark deck, you must replace them. Your belt is more likely to come off pulleys when they are not sitting flat.

Check the bearing in your pulleys. Turn each pulley by hand to confirm they are moving smoothly. If you feel any resistance or hear noise coming from your bearing, you must replace your pulley.

Bad Bearings in Your Spindle Housings

Bad bearings in your spindle housings can cause excessive vibration causing your Exmark belt to come off your pulleys.

To check for bad bearings in your spindle housings, grab a hold of each side of your mower blade and rock them up and down. Feel for movement or a knocking noise which indicates you have a bearing problem.

When you have these symptoms, remove your cutter housings. Exmark uses a spindle housing with a sealed bearing. You will have to replace the whole assembly. You can find instructions on replacing your spindle housing here.

Debris in Grooves of Pulleys on Your Exmark Mower

Small stones, wood chips, acorns, and other items can get caught in your pulleys. You may even find mud and debris caked in the groves of a pulley.

An Exmark mower belt can break when the debris is caught in the deck and under the pulleys. The stress on the belt when it has to stretch around the additional debris can cause the belt to break.

Belts don’t always break because they are old. Many times, new belts snap because a foreign material is caught in the pulleys.

Idler Tensioner Bracket or Spring is Worn

Your Exmark uses an idler bracket that holds the idler pulleys in line. You will find a spring on one side of the bracket and a pulley on the other side.

The spring can wear and become stretched or the hole in the bracket where the spring attaches can become worn. This can cause a constant Exmark vibration.

The bushing in your idler bracket can wear if it is not greased. When this happens, the pulley can begin running on an angle. The vibration along with a pulley that is sitting on an angle can cause your Exmark belt to come off.

Debris Interfering with Proper Tension on Belt

Running your Exmark can kick up a lot of dirt, grass clippings, and debris which can collect on top of your mower deck. This debris can inhibit the tension pulley’s ability to move as designed.

When this happens, proper tension is no longer able to be kept on your belt. Your belt won’t stay tight to the pulleys and can come off your mower.

It is important to keep your lawn mower clean under your belt covers. After each mowing, remove your belt covers and clean the debris out of this area to allow your deck to operate correctly.

With a clean deck, you will also be able to better identify problematic parts on your Exmark and stay proactive with repairs.

Check out our articles, “How to Clean Your Lawn Mower for Best Performance” and ” How to Find & Prevent Substantial Lawn Mower Deck Problems ” to learn more on how to keep your mower clean and in good condition to extend your mower’s lifespan.

Rust or Oil on Your Exmark Belt

Rust can buildup up your belt from rusting pulleys. Rust will cause your Exmark belt to dry out and crack prematurely. Clean the rust off your pulleys or replace them with new pulleys if they are excessively rusty.

When you develop an oil leak, oil can drip on the deck and belt. The oil that remains on your belt for a long time can cause your belt to swell. It can also cause your belt to not be able to grab a hold of your pulleys or slip off your pulleys.

Related Items

How Long Do Exmark Mower Belts Last?

Lawn mower belts can be very pricey depending on the manufacturer and type of mower you are running. Drive belts and deck belts are two of the most common lawn mower belts. Belts can cost anywhere from $60 to $250.

I recommend purchasing an OEM belt from the manufacturer of your lawn mower. You can probably find a cheaper belt online or have a local auto parts store try to match the belt for you, but they rarely last as long or perform as well as an OEM belt.

There are many factors that can impact how long your mower belt will last. To find out more details read my article, “This is How Long a Mower Deck Belt Should Last”.

More Exmark Mower Deck Problems

When you own your Exmark mower long enough, you will run into problems with your mower deck. I share some more information on repairing Exmark deck problems in my articles on fixing Exmark mower deck problems and solving your Exmark’s uneven cut.