Step-by-step guide to replacing spark plugs on a John Deere D100 lawn mower. Covers safety precautions, required tools, and troubleshooting tips to keep your mower running smoothly.
A dirty or faulty spark plug could make your mower hard to start, cause the engine to run unevenly, or misfire under load. All of this trouble is avoidable because a spark plug is easy to change. We'll show you how. You'll need a wrench with a spark plug socket and a spark plug gap tool. To measure the spark plug gap, check your operator's manual to make sure you have the correct spark plug for your ride on mower. And for important safety information, park the mower safely on a hard, flat surface with the engine shut off, parking brake on and key removed. If your ride on mower has a V twin engine, there will be two spark plugs, one on each side of the engine. First, remove the spark plug wire. Then use the spark plug socket and turn the plug counterclockwise to loosen and remove. This is a fouled spark plug covered with carbon deposits and gunk. A good working spark plug should be clean, like this one here where the spark happens. If this area is fouled, there won't be proper spark and the engine will run rough or not start at all. Your best bet is to discard a fouled plug and install a new one. You may also find carbon spark plugs that are cracked or with a damaged electrode area. These spark plugs should also be discarded. The new spark plug is probably not set up at your engine's recommended gap, so use your spark plug tool to check and adjust the gap. Check your operator's manual for the gap size. It will also have the recommended maintenance schedule for your mower. Or for quick reference, there is a machine maintenance sticker usually located in the engine compartment area. To set the recommended gap, gently bend on the outer electrode, then recheck the gap. With the gap properly set, tighten the spark plugs back in place, reattach the spark plug wires and then move the mower outside and start the engine. Remember that a fouled plug can also be a symptom of other problems bad fuel, a carburetor that's out of adjustment, or a clogged air filter. If your mower spark plug faults regularly, have your John Deere service technician check out the engine to find problem. Proper maintenance is the best way to make sure your mower starts quickly, runs efficiently and mows a beautiful lawn. To purchase parts, visit your local John Deere dealer.
