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How to Change the Mower Blade of a Lawn Boy

By Christina Wheeler ; Updated September 21, 2017
A sharp blade will prevent lawn damage.
grass image by Brett Bouwer from Fotolia.com

Performing routine maintenance on your lawn mower will keep your lawn looking its best while saving money. With simple tasks like changing the oil, maintaining the blades and cleaning the air filter, a mower will last longer and require fewer service calls. Lawn Boy recommends changing or sharpening the mower blade annually. Inspect the blade often for rust or damage and replace as needed.

Empty the gas tank. Run the mower until the mower has run out of gas. Remove the sparkplug wire from the plug. Grip the sparkplug wire and twist off the plug end. Tilt the mower onto its side and secure the blade with a block of wood to prevent it from moving.

Remove the nut from the center of the blade. Turn counterclockwise to loosen the nut, using the wrench. Remove the nut and blade from the drive shaft, lifting them away from it.

Replace the blade with a new or sharpened one; sliding it curved side down onto the drive shaft. Replace the nut onto the shaft and tighten by hand. Place a wood block against the blade to secure it and tighten the nut further with a wrench.

Turn the mower upright. Pour gasoline in the tank and replace the sparkplug.


Things You Will Need

  • Wood block
  • Wrench
  • Gasoline


  • Wear gloves while working on the lawn mower to prevent injury.