How to change spark plug in lawn mower?

How to change spark plug in lawn mower?


Changing the spark plug in a lawn mower is a simple yet essential maintenance task that can greatly improve the performance and efficiency of the machine. A spark plug is responsible for igniting the fuel-air mixture in the engine’s combustion chamber, and over time it can become fouled or worn out, leading to starting issues, poor fuel economy, and reduced power output. In this article, we will guide you through the step-by-step process of changing the spark plug in a lawn mower, ensuring that your machine continues to run smoothly.

Gather the Necessary Tools and Materials

Before you begin, it’s important to gather all the tools and materials you’ll need for the task. Here are the items you’ll typically require:

– New spark plug (make sure it is the correct type for your lawn mower)
– Spark plug socket or wrench
– Socket extension (if necessary)
– Gap gauge or feeler gauge
– Anti-seize compound (optional, but recommended)

– Safety gloves
– Safety goggles
– Socket set
– Ratchet handle

Locate the Spark Plug

The spark plug is usually located on the side or top of the engine, covered by a rubber boot or wire. Start by disconnecting the spark plug wire/boot from the plug. It’s important to wear safety gloves and goggles to protect yourself from any potential sparks or debris.

Remove the Old Spark Plug

Using a spark plug socket or wrench, carefully loosen and remove the old spark plug by turning it counterclockwise. If the plug is difficult to remove, you can use a socket extension for better leverage. Take your time and avoid damaging the threads or the surrounding components.

Inspect and Gap the New Spark Plug

Before installing the new spark plug, it’s crucial to inspect it for any signs of damage or defects. Check the electrode and ceramic insulator for cracks, and ensure that the gap between the center and ground electrode is correct. Most spark plugs come pre-gapped, but it’s always a good idea to double-check using a gap gauge or feeler gauge. Refer to your lawn mower’s manual or the spark plug manufacturer’s specifications for the correct gap measurement.

Install the New Spark Plug

Once you have inspected and gapped the new spark plug, apply a small amount of anti-seize compound to the threads (if recommended by the manufacturer). Carefully thread the spark plug into the engine by hand, making sure it is properly aligned. Use the spark plug socket or wrench to tighten it, but be cautious not to overtighten, as this can damage the threads or the plug itself. Refer to the manufacturer’s torque specifications if available.

Reconnect the Spark Plug Wire/Boot

After the new spark plug is securely installed, reconnect the spark plug wire or boot by pushing it firmly onto the plug until you feel it click into place. Ensure that it is properly seated to prevent any potential misfires.


Changing the spark plug in your lawn mower is a straightforward process that can have a significant impact on the machine’s performance. By following the steps outlined in this article, you can ensure that your lawn mower continues to start easily, run smoothly, and maintain optimal fuel efficiency. Regularly inspecting and replacing the spark plug will help prolong the life of your lawn mower and save you from potential headaches down the line.


– Briggs & Stratton:
– Honda Power Equipment:
– Toro:
– Husqvarna: