Step-by-step guide to replacing the spark plug on a John Deere D100 lawn tractor. Covers safety tips, required tools, and troubleshooting 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 the 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 plugs for your tractor and for important safety information, park the mower safely on a hard, flat surface with the engine shut off, parking brake set and key removed. If your tractor has a V twin engine, there will be two spark plugs, one on each side of the engine. First, remove the spark plug wires. Then use the spark plug socket and turn the plug counterclockwise to loosen and remove the spark plug. 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 a proper spark and the engine will run roughly or not start at all. Your best bet is to discard a file 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 at your engine's recommended gap, so use the spark plug tool to check and adjust the gap. Check your operator's manual for the gap distance. It will also have the recommended maintenance schedule for your mower. Or for quick reference, there's a machine maintenance decal 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 plugged air filter. If your mower spark plug fouls regularly, have your John Deere dealer service technician check out the engine to find the 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 or go to www.jdparts.deere.com.
