Q: I heard somebody say once that you should disconnect the spark plug before you change your mower blade. Why?
A: Probably the most important safety precaution that you can take when doing your own repairs or maintenance on a lawnmower is to disconnect the spark plug wire before you do anything else. This is especially true when doing anything with the mower blade. Mowers start by centrifugal force that turns the crankshaft (where the blade is attached) until a spark is created that starts the combustion process. Sometimes it doesn’t take much movement in the blade to start the process and you don’t want to be anywhere near that mower blade if the engine turns over.
To disconnect the spark plug, simply remove the rubber “boot” that connects the spark plug to the wire and turn it so the back of the boot is facing the spark plug.