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Lawn Mower Spark Plug Replacement Instructions


Walk-Behind Lawn Mower Spark Plug Replacement Instructions

As part of routine maintenance, it's important to check and replace the spark plug for your walk-behind lawn mower. Performing this maintenance item will ensure easier starting and that your machines' engine performs as designed

Follow the instructions below to inspect and replace the spark plug. Note that the instructions for changing the spark plug on your lawn mower may be slightly different than those noted below - reference your operator's manual for instructions specific to your model.

Before starting, make sure you have the tools needed to replace the spark plug, including a spark plug socket wrench and a gap tool.

If your lawn mower is damaged from hitting an object in your yard or has complicated engine trouble, it is best to take it to a local MTD certified service dealer for repairs.


Step 1: Position the lawn mower

Place your walk-behind lawn mower on a flat, level surface.

Step 2: Disconnect the mower spark plug wire

Disconnect the mower spark plug wire from the spark plug.

Step 3: Remove the old mower spark plug

Use a spark plug socket wrench to remove the old spark plug. Turn the spark plug counterclockwise until the plug is removed from the engine.

Step 4: Change the spark plug

Check the gap on the new spark plug by using a spark plug gap tool or a set of feel gauges to adjust the gap. Refer to your operator's manual for the correct gap. Install the new mower spark plug, being careful not to cross-thread the plug. You should be able to thread it in smoothly by hand for a few turns.

Step 5: Tighten the mower spark plug

Using the spark plug wrench, continue tightening the spark plug. Make sure the mower spark plug is in tight, but do not over-tighten it.

Step 6: Re-attach the spark plug wire

Once you've replaced the lawn mower spark plug, reconnect the spark plug wire to the spark plug.

Fix equipment issues quickly

When you need parts for your walk-behind lawn mower, you can use the MTD Genuine Parts Part Finder to find the correct one. Common parts include:

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The MTD Genuine Parts Knowledge Center provides do-it-yourself instructions for performing many basic maintenance items, including replacing cutting blades, drive and deck belts, and engine oil. If you find your machine has a bigger problem, use our service locator to find a qualified MTD service provider in your area.