John Deere S100 Deck Belt Diagram (2024)

FAQs

Why does my John Deere deck belt keep breaking? ›

A common cause of belt breakage is excessive grass clippings on the deck. Grass clippings can work their way under pulleys and deck covers, causing series problems. Make sure to clean off your deck after every mower use and follow manufacturer recommendations.

Belt tension adjustment is an iterative process that requires removing the Drive Belt for each incremental tension adjustment. The process entails: making a belt tension measurement, removing the Drive Belt from the motor pulley, changing the motor position to adjust the belt tension.

The belt tension is set with a spring and an eyebolt. Tighten or shorten the eyebolt to increase belt tension or loosen or lengthen the bolt to relieve tension. The correct tension is achieved when pressure is applied to the center of the longest run and belt is able to be pressed in about ½” from static position.

The biggest cause of belts flying off of a mower deck is that the customer does not know that you MUST engage the mower with the engine running at FULL THROTTLE. Engaging the mower at anything less than full throttle can throw the belt off. The next thing that will cause this is an IDLER pulley beating that is dry.

The first potential culprit of your mower belt repeatedly breaking could be faulty bearings on your spindle or pulley. These components rotate at high speeds during operation, leading to intense heat that can potentially damage the bearings if not properly maintained.

There's no definite amount of time that a mower belt is supposed to last, but increased mower use shortens the interval in which a belt needs replacement. Simply put, more use equals more wear. Additionally, faulty belts or mechanical failures like a seized pulley can make lawn mower belts break prematurely.

And a cooler running engine and better filtering helps increase engine oil life. John Deere's recommended oil service for 100 Series Riding Lawn Tractors¹, is to change the System every 50 hours or once a season, whichever comes first. Remember, the System replaces a portion of your engine oil.

A low charge may not provide enough juice to engage the PTO. If you do hear the click, there is power going to it. There could be a problem with safety switches. On most newer model lawn mowers, the brake has to be disengaged or off for the blades to operate.

If the blades are not rotating, put the ride-on mower into the service position and check for grass, branches or other debris. If the cutting deck is dirty, clean it by removing all branches, grass or debris.

As such, you'll need to take our recommendation with a grain of salt and do a bit more research into your specific vehicle/belt/other systems. In general, though, tension lower than ½” is considered too loose - and tension over ½” is considered too tight. That's the sweet spot to shoot for.

Why does the belt keep coming off my riding lawn mower? ›

The biggest cause of belts flying off of a mower deck is that the customer does not know that you MUST engage the mower with the engine running at FULL THROTTLE. Engaging the mower at anything less than full throttle can throw the belt off. The next thing that will cause this is an IDLER pulley beating that is dry.