We recommend replacing the spark plug every year because it is so simple and inexpensive however, depending on your lawnmower use this may not be necessary. Step 3: Determine whether the plug needs to be replaced. If the plug is in an easy-to-access location as it is on both of our mowers, a pair of channel locks will work great. You can find them at most major hardware & auto parts stores. If you’re planning to do car tune ups in the future, this type of socket is essential. This special socket has a deep well and a hard foam insert that grips the plug during installation and removal. If the plug is embedded deep inside a hole, you may need to use a spark plug socket to grip and remove it. The tool required to unscrew the plug depends on the plug’s location. Step 2: Remove the spark plug wire and unscrew the plug from the engine. On both our Briggs and Stratton engines, the plug is located in roughly the same spot. On a lawnmower engine, the plug location is usually obvious, as the wire that provides the electricty for the spark connects to the end. Step 1: Locate the spark plug on the engine. Here’s the few steps required to change the plug: How to Change a Lawnmower Spark Plug Most lawnmower spark plugs are $2.00 or less at the local hardware store. The second can result in an engine that rattles or vibrates, and occasionally stalls.įortunately, changing a spark plug is both simple and inexpensive.
When a spark plug detoriates too much, it loses its ability to generate a full spark, and two things can result: (1) the spark plug cannot produce sufficient spark to ignite the fuel in the chamber, and the lawnmower won’t turn over at all, or (2) the spark plug produces a sub-optimal spark, and the explosion inside the chamber is uneven. Since it sits inside the cylinder, it is subject to very high heat, corrosion, and wear. The spark plug ignites the repeated explosions inside the cylinder of a lawn mower’s engine. One of the top reasons a lawnmower won’t start is a faulty or worn out spark plug. Both push mowers are powered by Briggs & Stratton small engines. While this post is focused on replacing the spark plug in a push-type lawnmower, the basic principles can be applied to all 4-cycle gas powered equipment (including such things as a pressure washer or chipper shredder, and even an automobile).įor the entire series, we’re performing maintenance on both a Craftsman 6.5 horsepower self-propelled mower, and a 4.5 horsepower Murray mower.
This article is the fourth in a series of maintenance articles that cover complete mower care. Performing full mower maintenance once per cutting season is important to keep your mower in top running shape.