How to Replace the Spark Plug on a Push Mower

Let the engine cool completely before working near the spark plug.

Locate the spark plug — it's on the side or top of the engine with a thick rubber boot and wire attached.

Pull the spark plug wire boot straight off the plug. Don't pull on the wire itself.

Clean around the spark plug base with a rag to prevent debris from falling into the cylinder when you remove it.

Using the spark plug socket and ratchet, turn the plug counterclockwise to remove it.

Check the gap on your new spark plug using a gap tool. Most small engines call for 0.030 inches. Adjust by carefully bending the ground electrode.

Thread the new spark plug in by hand first to avoid cross-threading. Turn it clockwise until finger tight.

Tighten with the socket wrench — about 1/4 turn past finger tight for a new plug with a crush washer. Don't overtighten.

Push the spark plug wire boot firmly onto the new plug until it clicks or seats fully.