Step 1: Remove the spark plug boot and spark plug. Locate the spark plug boot and remove it, exposing the spark plug. Use a deep spark plug socket and ratchet to loosen the spark plug by turning it counterclockwise. Once it is loose, remove the spark plug by hand.
Use a ratchet and deep spark plug socket to loosen the spark plug.
Step 2: Replace the spark plug. Use a replacement spark plug that is identical to the old one. Set the spark plug gap by using a spark plug feeler gauge. Set the gap according to the owner manual's recommendation. Install the spark plug, turning clockwise by hand. Finish turning with a socket. Once the spark plug is seated, give it one half turn more. Replace the spark plug boot, pressing until you hear a "click."
Step 3: Prepare the mower to clean by laying it on the ground, exposing the underside. Remove the spark plug cover to prevent the engine from starting. Position a pan to collect any oil that might drip from the oil breather vent. Turn the mower on its side. Rest a block of wood against the grass shoot and turn the blade to rest against the block to prevent it from moving.
Position a block of wood between the chute and the blade.
Step 4: Remove the old blade. Use a box wrench to loosen and remove the bolt that secures the old blade. Mark the bottom of the blade with an "X" to help when installing the new blade. Remove the old blade and the wooden block.
Step 5: Locate and clean the oil drain plug. Locate the oil drain plug. Use a wire brush and a scraper to clean the area surrounding the oil drain plug. Remove caked grass clippings. Place newspapers around the area to collect the clippings and position a waste collector beneath the oil drain plug.
Find the oil drain plug and clean the surrounding area.
Step 6: Remove the oil drain plug and drain the oil. Use a ratchet, extension and socket to loosen and remove the oil drain plug. Quickly lower the mower to help drain the oil into the collection pan. Allow the oil to drain for a few minutes. When the oil has finished draining, lift the mower back on its side and quickly replace the oil drain plug, tightening until snug with a ratchet and socket.
Step 8: Install the new blade. Orient the new blade the same way the old blade was oriented, using the "X" you made on the old blade as a guide. Place the blade over the engine shaft, replace the bolt and tighten until snug. Re-position the block of wood as necessary against the edge of the casing and another engine bolt, and rest the new blade against the wooden block. Use the box wrench to tighten the bolt completely. Remove the wooden block and lower the mower.
Tighten the bolt with a box wrench with the blade resting against the wooden block.
Step 9: Fill the mower with oil. Remove the oil fill cap and set it aside. Refer to the owner's manual to determine the correct quantity and weight of oil to use. Always use a premium-grade detergent oil. Slowly pour the oil into the filler tube, being careful not to overfill. Use the dip stick to check the level of the oil and fill to the "full" mark.
Step 11: Condition and replace the air filter. When the air filter has dried, pour a few tablespoons of motor oil on the foam filter and work it in thoroughly. Squeeze out any excess. Wipe out the air filter housing and replace the air filter. Replace the air filter cover and fasten it into place.