How to Loosen a Tight Spark Plug in a Lawn Mower

Pull the spark plug wire away from the spark plug. Brush the seam between the spark plug and the engine with a stiff wire brush. This helps to loosen and remove rust, as well as loosen the seal created by the intense heat.

Put on safety goggles. Spray compressed air over the spark plug area to remove the broken rust and sediment. Slide the spark plug wire over the top of the spark plug.

Start the lawn mower and allow the engine to reach operating temperature. Heating the engine expands the threads just enough to loosen and remove the spark plug. Once the engine reaches operating temperature, turn off the lawn mower.

Put on a pair of leather work gloves to avoid burning your hands on the hot engine. Pull the spark plug wire off the spark plug.

Attach an appropriate size spark plug socket on a socket wrench. Spark plug sockets have a cushion inside to help protect the top of the spark plug from cracking or breaking off when removing it from the engine.

Place the socket firmly over the spark plug. Rotate the plug counterclockwise with the socket wrench. If necessary, slide a breaker bar over the handle of the socket wrench for extra leverage. A breaker bar is a steel tube that is usually two feet long.