How to Replace a Lawn Mower Blade


To maintain a crisp lawn appearance, a sharp mower blade is essential. A dull blade will tear at grass rather than provide a clean cut, damaging the lawn and leading to dead areas of grass. Most manufacturers recommend sharpening or replacing the mower blade once per mowing season. This can be completed easily at home, with a trip to your lawn service supplier. Many blades can be ordered online for an even more cost-effective way to maintain your mower.

Step 1

Disable the mower from starting. Remove the spark plug cord from the spark plug. This will ensure that there is not a spark to the engine, causing an accidental start. It is imperative that the mower is disabled to safely change the blade

Step 2

Remove any old gas and oil from the mower. Since the mower will be tipped on its side, these fluids will leak out of the mower. Use a siphon to remove the gas from the tank, or simply mow until the tank runs dry. Do not use the same siphon when removing the gas and oil. The fluids will become mixed, causing engine problems when reinserted into the mower.

Step 3

Tilt the mower on its side. Secure the mower with a concrete block or lay on a workbench to prevent it from tipping back over. Secure the blade with a block of wood so that it cannot turn. Clean away any old grass and debris under the mower. Put on the sturdy work gloves.

Step 4

Remove the blade by turning the nut in the center of the blade with a wrench. If you have not changed the blade for some time, it will be difficult at first. If it is stubborn to turn, apply the wrench and tap the end with a rubber mallet to loosen the nut. Remove the block of wood once the nut is loose. Hold the blade with your gloved hand and continue turning the nut until it slides off the bolt. Remove the blade.

Step 5

Replace the blade with a new one of the same size. Position the blade on the bolt so that it will turn with the sharpened blade in the same direction as the removed blade. Replace the nut and tighten by hand securely. Turn the blade with your hand to ensure it is attached well and not loose.

Step 6

Turn the mower back to an upright position. Wipe away any leftover gas or oil that may have leaked out. Replace the oil in the engine and refill the gas tank. Reattach the spark plug wire to the spark plug. Start your mower, and enjoy your new sharpened blade for another year of great grass cutting.

Tips and Warnings

  • Always double-check that the engine is disabled before placing hands near the blade.

Things You'll Need

  • Siphon
  • Block of concrete
  • Block of wood
  • Sturdy work gloves
  • Wrench
  • Rags


  • Home Service Engine: Lawn Mower Blades
Keywords: lawn mower, mower blade, lawn care