Why Does The John Deere Mower Deck Belt Keeps Coming Off?

The deck belt is one of the most crucial instruments of your John Deere lawnmower, which connects the crankshaft to the blades, making them turn. So, it’s important to keep the belt away from any kind of problem. 

If the belt gets broken or rusty or debris hampers the movement, the belt will keep coming off. Regular maintenance may help in this regard. 

However, if you already face some problems with it, it’s important to solve the problem. So, let’s read and learn why John Deere mower deck belt keeps coming off and the solutions for John Deere Mower Deck Belt.

Troubleshooting John Deere Mower Deck Belt Problems

When you have a John Deere mower, you can face problems with the deck belt. Scroll down below to know why the john Deere mower deck belt keeps coming off.

1. Loose or Worn John Deere Deck Belt

Sometimes, for overusing or weather issues or the surroundings, the rubber-made john Deere mower deck belt stretches while mowing. It causes especially for the flaws of the pulley. 

If the pulley doesn’t function normally, then the malfunction occurs. And if you find the pulley stretched once, you cannot have better performs from the mower anymore. You have to fix it, which is quite easy but tricky. 

First of all, you have to check the pulleys and bearings of the pulleys. 

If they are not in place, such as bearings coming out from the pulleys or the pulleys becoming misplaced, place all of them correctly. Then insert a new mower deck belt on the John Deere mower deck. 

If the pulleys are okay, mostly, it will prevent the destruction of the belt. One of the most common causes of the damaged deck is having excessive grasses in the john Deere deck. It can easily displace the pulleys and stretch the deck belt. 

In this matter, you have to stop after a fixed period, like after every twenty minutes of mowing, and clean the deck and mowing again.

It will help you to keep your John Deere mower deck alright. And for worn deck belts, just change them for having a good mowing experience.

2. John Deere Mower Deck Belt Breaks or Heated up

John Deere mowers are quite heavy using. So, it is possible that the belts break while mowing and come off the deck. In that case, maybe the belt got stretched and created friction with the pulleys or the deck cover. 

After some unsatisfactory cuts, the belt breaks and comes off the mower deck. It is a countable problem while mowing, and you obviously have to solve it immediately.

Perform your precautionary steps carefully. If you find abnormal cutting, turn off your John Deere Mower engine and check the deck carefully. If it is broken, clean the deck and adjust the pulleys and replace a new belt. 

Sometimes broken belt causes too much heat before breaking when it is loose. Try to find this problem before mowing and solve it as mentioned earlier.

3. Oil and Rust on the Belts

John Deere Deck may collect an excessive amount of oil and rust from other parts of the deck. Rust can build on the belt surface and make the belt drier. 

Dry belts cannot stretch about to their normal capability and break down. 

In that case, you have to keep your John Deere Deck cleaner and perform a precautionary function test before mowing. 

4. Damaged John Deere Mower Deck Belt Keeper

John Deere Mower deck belt keeper is a rod that helps to keep the belt in place sits between ¼” to 1/8” away from the pulley. 

Sometimes it can get bent because of slack in the belt. If the rod is not okay, the belt may feel stretched, and that’s why you cannot have the best from the belts.

You can find bent keepers while performing precautionary steps. Use a hammer and straighten the keeper. If it does not work, change the belt keeper.

5. Debris Interface

Excessive dust and other particles actually resist the belts from their usual turning. If it does, you may feel your belt is not performing well, but you cannot fix it by changing the belt. 

It’s important to keep the interface always clean so that there is no excessive grass or oil or grease and all. It helps the belt to perform properly. Be cautious about the interface while performing the inspection.

6. Other Damaged Parts

Sometimes other damaged parts like tensioner or spring, which keeps the pulleys in place, can cause deck belt problems. 

You have to know about the structure of the mower deck. While performing the security check of the deck, check if the things related to the belt are okay enough or not. If it is not in place or something, replace them.

These are the most common problems regarding the john deere mower deck belt. If you cannot handle it anymore, take the expert’s opinion.

How Do I Know If My John Deere Mower Belt Need Replacement? 

You can understand if the belt is beyond its life just by inspecting the belt carefully:

Check if the edges of the belt are smooth throughout the length. If you find any sidewall damage, the belt should be replaced.

If the belt edge that contacts the pulleys appears shiny or burned, it needs to be replaced.

If the belt has any crack, it is time to replace the belt.

Why do My John Deere Mower Belts keep On Breaking?

If it happens again and again, the bearings may have worn out. When the mower’s pulley cannot spin freely, the friction created between the machine and the belt can cause it to break.


Some customers complain that the John Deere mower deck belt keeps coming off. I hope that they have now got the solutions. So, let me know about your experience on John Deere Mowers.

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