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How to Replace the John Deere Lawn Tractor 300X Drive Belt

Replacing the drive belt on a John Deere 300X will increase the cutting efficiency of the mower deck if the original belt is worn beyond the idler pulley's ability to compensate. As the belt stretches, the spring-loaded idler pulley creates additional tension on the belt. Eventually, the pulley runs out of travel and no longer has the ability to supply adequate tension. When this happens, the belt slips on the pulleys and the blades do not run at optimum speed. To correct this issue, replace the belt.

Things You'll Need

  • Socket set
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    • 1

      Park the John Deere 300X lawn tractor on level ground, set the parking brake and lower the mower deck into its lowest cutting position. This gives you maximum room between the 300X and the mower deck.

    • 2

      Disengage the PTO lever to turn off the mower blades. This creates enough slack in the drive belt for you to slip the belt off the pulley system.

    • 3

      Remove the belt guard that rests over the drive pulley mounted under the John Deere engine with a socket and ratchet. Place the guard off to the side.

    • 4

      Pull the belt off the drive pulley mounted on the John Deere engine, then pull the belt back towards the mower deck.

    • 5

      Pull the belt off the spindle pulleys and idler pulley on the mower deck. Place the new belt onto the pulleys. Stretch the belt towards the front of the John Deere 300X and place the belt over the drive pulley.

    • 6

      Place the belt guard over the drive pulley and secure it with the socket and ratchet.