Reasons Craftsman Riding Mower Deck Belt Keeps Coming Off

Nothing is more aggravating than having to halt mowing in the middle just because your Craftsman deck belt keeps falling off. But what drives the Craftsman mower belt to keep coming off?

 4 most common causes behind such a commotion are:

• Wrong size/type or incorrect installation of Deck Belt.
• Improper tension on the Blades or Belt.
• The Deck Wheels or Pulleys are misaligned.
• wear and tear on the Belt or Pulleys.

Aside from the causes mentioned, other potential conditions can cause your Craftsman Riding mower deck belt to come off. Hence, keep reading to find out more about them and how to solve the problem.

6 Additional Reasons Why Craftsman Deck Belt Keeps Coming Off:

• Bent or Damaged Deck Belt Keeper
• Loose, Stretched, or Shredded Deck Belt
• Damaged Bearings or Spindle Housings
• Worn-out Idler Tensioner Bracket or Spring
• Built-up Debris, Oil, or Rust on Your mower Deck Belt

8 Things to Consider If Your Craftsman Riding Mower Deck Belt Keeps Coming Off:

Immediately check the following fault areas to find out the exact problem_

1. Choose the Correct Deck Belt Size/Type & Installed it Accordingly: 

You can always get cheaper aftermarket parts whenever you need to replace the current one. But these aftermarket options cannot beat the quality of an OEM belt.

Because OEM options last longer and minimize safety concerns.

Make sure that the belt you select can withstand the stress exerted by the mower.

Standard V-belts are usually good. However, depending on the model of your mower, more options are available.

To select the right size of deck belt for your Craftsman, you need to know the make and model number of your mower, which is available in your user manual.

If you do not have the user manual, check on the deckle under the mower hood, you will see the part number there.

Or use a belt measuring tool to measure the current deck belt to choose the new one.

Also, make sure that you have installed it correctly.

2. Look For Improper Tension on the Deck Belt

If the deck belt on your Craftsman riding mower is not properly tensioned, it will come off during mowing.

Once you are sure that you need to adjust the belt tension to prevent it from slipping, inspect the swing arm first.

Then, disengage the blades to adjust the belt tension correctly.

Note: before you start performing the adjustment make sure that no cracks or big chunks are missing from the belt. Otherwise, you must replace the belt.

3. Check For Misalignment

If the deck, deck wheels, or pulley is not aligned correctly, the Craftsman deck belt will not stay in place and keep coming off unless you adjust the alignments as needed.

The mower deck:

If the deck has a wrong alignment, you need to adjust the blade height and level to adjust the alignment.

• Set the blade at its highest setting.
• Measure 3 inches from the ground in four separate places around the outside of the mower deck.
• Compare those measurements.
• If they are not similar, adjust either one or both front and rear adjustment screws until they become equal.

Mower deck wheels:

Follow the below instructions to align the deck wheels accurately_

1. Park your Craftsman on a level surface and turn off the engine.
2. Lift the mower hood to locate the adjustment screws for each wheel.
3. Turn each screw clockwise to increase or decrease its height until all four wheels look leveled from all angles.
4. Once you have achieved the desired alignment of the wheels, tighten down all adjustment screws securely.

The pulley:

Follow the below instructions to align the misaligned pulley_

• Lift the mower hood to locate the pulley.
• Check whether all tension springs or idler arm components are tensioned properly or need adjustment.
• Loosen their mounting bolts slightly to adjust them accordingly if needed.
• Make sure all components are securely tightened.
•  Check the Condition of the Deck Belt Keeper: 

The small rod-shaped poles sitting next to the pulley on your Craftsman riding mower are known as the belt keepers.

These keepers mainly guide the belt to keep it in place.

But these keepers might bend outward or move out of place and allow the deck belt to jump out of the pulley due to excess slack in the belt or when the belt snaps.

So, take the pulley off and bend this tab to get the keeper closer to the pulley.

Check and do the same thing to confirm that all the keepers are as close to the engine pulley as possible.

If any belt keepers have turned too bad to fix like that, replace them.

4. Make sure That the Deck Belt Is in Good Condition

Your Craftsman deck belt tends to come off when it has become loose. It can become loose when the belt has worn out or stretched over time.

You can also notice shredded marks on the belt. When the belt rubs against a bracket or your belt keepers, it leaves shredded marks.

It occurs due to improper adjustment of the brackets and belt keepers.

If your deck belt has become loose due to wear and tear or stretching, you should replace it. If you have a shredded belt, determine where the markings are coming from and correctly adjust that location to avoid rubbing.

 5. Inspect the Idler Tensioner Bracket or Spring

Your deck belt can also keep falling from its position due to a worn-out idler tensioner bracket or spring.

Therefore, visually inspect and look for any signs of corrosion, cracking, or other hints that indicate either the tensioner bracket or the spring is worn.

Also, test the tensioner by pushing on it, and if there is any excess play or movement, it’s time to replace the idler tensioner bracket or spring.

6. Inspect the Bearings or Spindle Housings

You also need to check the bearings located in the idler pulley and spindle housing because if one of those bearings fails, it will gradually cause the belt to fall off.

If the pulleys are rotating straight rather than flat, one of the bearings has failed.

So, check and replace the bearings in the pulley.

7. Keep the Deck Belt & Pulley Cleaned

Built-up debris and grass can restrict the belt tensioner work. If that happens, the deck belt will not stay tight.

Therefore, Keep your Craftsman deck clean.

Sometimes, these riding mowers develop an oil leak. When the leaked oil drips onto your pulleys and belts, it causes your belt to slip from its position.

So, keep the pulleys clean of such leaked oil and built-up rust.

Related Post: 42 vs 48 Inch Mower Deck: 6 Key Factors Make the Actual Differences

Frequently Asked Questions (FAQs)

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