Having to stop mowing, get off your mower, and replace your Husqvarna belt because it keeps falling off can get very frustrating. The only way to prevent it from continuing to happen is to find the root cause of the problem.

A Husqvarna mower belt can keep coming off your mower when the deck belt is worn, stretched, or shredded. Excessive vibration can cause a belt to come off your pulleys when a bearing, tensioner bracket, or tensioner spring is worn.

There are additional factors that can cause a mower belt to come off. I have prepared a list of reasons so you can get identify your belt problem.

Reasons Your Belt Keeps Coming Off Your Husqvarna

• Loose or worn belt
• Belt keeper damage
• Shredded deck belt
• Bad spindle housing bearing
• Bad pulley bearing
• Worn tensioner bracket or spring
• Debris interfering with belt tension
• Debris stuck in the groove of the pulley
• Oil or rust on the belt

Loose or Worn Husqvarna Belt

A Husqvarna belt will wear from normal use and it can become loose causing it to come off your pulleys. Inspect your belt and check it for wearing, cracking, or a shiny glazed appearance. It’s time to replace your belt when your belt has any of these conditions.

Husqvarna Belt Keeper Damage

Belt keepers are installed around your pulleys to do just want the name indicates. It helps keep the belt in place. A belt keeper is a rod that sits between 1/8” and ¼” away from the pulley.

Your belt doesn’t touch the keepers. The keepers are rods added as a prevention to keep your belt from slipping off your pulleys.

The keepers can become damaged when slack in the belt hits a keeper and bends it out of place. The belt can then slip off the pulley when your belt keeper is damaged. To fix the keeper, you can attempt to bend the rods into place using vice grips and a hammer.

Shredded Husqvarna Belt

A belt can become shredded and break or come off your Husqvarna’s deck. Most of the time, shredding of the belt occurs when a belt rubs against an object like a belt keeper or bracket on your mower deck. Another reason why your belt may shred is when it isn’t installed correctly.

If your belt is shredded, make sure you have it routed around your pulleys correctly.

Your mower may have a decal on it with a diagram showing the direction in which your belt is to be routed or you can find it in your owner’s manual. Next, check for any brackets or keepers your belt is rubbing against.

When the belt rubs on a metal component, you may find a shiny smooth spot on the metal. Fix the bracket so it no longer rubs.

You may have to replace a bushing on some brackets or need to replace a bracket assembly when the manufacturer doesn’t allow only the bushing to be replaced.

Bad Husqvarna Bearings in Your Husqvarna Pulleys

When your pulleys don’t sit flat and parallel to your mower deck, they can cause a vibration when your belt runs around your pulleys. Bad bearings in your pulleys can be the reason your pulleys don’t sit correctly on your deck.

One side of the pulley may have one side higher off the deck than the other. To check for a bad or failing bearing, spin each pulley by hand.

A good pulley will spin smoothly. You will feel a restriction when you spin a pulley that has a bad bearing. You may also hear a sound coming from the bearing indicating your pulley must be changed.

Idler pulleys have sealed bearings so you will have to replace the whole pulley assembly with the bearing already in place.

Bad Husqvarna Bearing in Your Spindle Housings

Check your spindle housings next as the bearings can go bad causing a vibration when you engage your mower deck. The vibration can knock a belt off your pulley.

Confirm you have removed your ignition key and unplugged your spark plug boot(s) to keep your mower from starting while working under your Husqvarna’s deck.

Wearing a good pair of work gloves to protect your hands from the sharp mower blades, grab each end of the blade. Rock the blade up and down to check for play or movement in the blade.

Movement or a knocking sound suggests a problem in your spindle housings. Remove your spindle housings and inspect for a bad bearing or bad spindle.

You may find you can replace a bearing in the spindle assembly, however some models will require you to replace the whole spindle assembly.

Husqvarna Idler Tensioner Bracket or Spring is Worn

Check out the idler tensioner bracket and spring. This is the bracket that holds the idler pulleys in line. You will typically find a pulley on one side of the bracket and a spring on the other side.

The spring can become weak causing your Husqvarna belt to come off your mower.

The hole in the tensioner bracket where the spring attaches can wear and become larger. This can cause additional vibration in your mower. When you find either a worn bracket or spring, you must replace the worn part.

Debris Interfering with Proper Tension on Your Husqvarna Belt

Debris can collect on top of your deck around your pulleys and tensioner. It is possible for the debris to keep your tensioner pulley from being able to move as designed.

Your belt can become loose when sufficient tension is not kept on your belt causing it to vibrate. It isn’t only important to keep the belt area of your mower deck clean and free of debris for performance reasons, it is also important for safety reasons as well.

Dry debris collected on the top side of your mower deck can catch on fire from the heat of the belt.  

Find out more details on cleaning your mower deck in my articles on cleaning your lawn mower and finding and fixing mower deck problems. A clean mower will not only improve performance, but it can also extend your mower’s lifespan.

Debris in the Grooves of Your Husqvarna Pulleys

A Husqvarna mower belt can snap and come off your mower when stress is put on the belt from stretching around additional material.

This can be from mud or small debris stuck in the grooves of a pulley. Check the grooves of your pulleys and clean them if necessary.

Oil or Rust on Your Husqvarna Belt

When your Husqvarna develops an oil leak, oil can get onto the belt and cause it to swell when it is covered in oil for a significant period of time. An oil-covered belt can cause your belt to slip on the pulleys and come off your deck.

Your belt can also be covered in rust from old rusty pulleys. Rust prematurely causes your belt to dry out and crack causing your belt to be more susceptible to breaking.

To fix an oil or rust coverage problem, repair the oil leak and clean any oil or rust off your deck and pulleys. If your pulleys are covered in a lot of rust, replace the pulleys.

Once you have taken care of items contributing to oil and rust on your Husqvarna deck, you should replace your mower deck with a new Husqvarna belt.

In Summary

Husqvarna deck belts can be pricey so the longer you can make them last, the better. Here are a few items that can extend the life of your Husqvarna mower belt to keep it from prematurely wearing or breaking and coming off your mower:

• Clean your mower deck after each mowing to remove debris
• Check for rubbing on deck components
• Keep oil and rust from forming on your belt
• Periodically check your pulleys and spindle housings for bearing failure
• Fix or replace any damaged brackets or belt keepers