Use a Spark Plug Gap Tool to check the distance between the electrode and the contact. This gap distance is a critical measurement to assure optimum spark efficiency and engine performance. The 'spark' that ignites the fuel inside the engine arcs across a gap at the base of the spark plug between the spark plug electrode and an adjustable curved wire ground contact.

The cost-to-benefit ratio of installing fairly inexpensive new plugs, as compared to expensive engine damage and reduced engine performance, make cleaning and re-using plugs a risky practice. NOTE: We do not recommend sanding or cleaning these carbon deposits, as this may damage the plug and any sand remaining on the plug may seriously damage the engine internal components. Replacement spark plugs and tune-up parts are available at our Online Parts Store. Plugs with noticeable carbon build-up should be replaced with new plugs. Inspect the plug for signs of black carbon deposits around the spark electrode at the bottom. * SPARK PLUG & RATCHET W/DEEP SOCKET TOOL To remove the spark plug slip the socket over the plug and rotate the wrench counterclockwise (lefty-loosey) until the plug comes loose and can be easily lifted away from the engine. The most common sizes of spark plug nuts and the sockets used to remove/install them are 15/16', 13/16' and 5/8'. The size of socket will vary with plug type and plug manufacturer. Although a standard deep socket will work, tool companies also make 'spark plug sockets', which have rubber inserts to protect the porcelain part of the plug from damage. The socket should be tall enough to slip down over the entire length of the plug and fit properly around the integrated retention nut at the base of the plug. Grasping the boot on the end of the wire and using a firm steady and slightly twisting back and forth pulling motion, a similar motion as to pulling a cork out from a bottle, carefully separate the boot end of the wire from the top of the spark plug.įor spark plug service, the tool of choice is a ratcheting wrench with the proper size deep socket. To access the spark plug for service the ENGINE MUST BE SHUT OFF AND ALLOWED TO COOL and then the protective boot on top of the spark plug will need to be removed.ĭO NOT PULL ON THE WIRE ITSELF, as this may damage the wire or separate it from the boot assembly

The boots are pressed over the top of the spark plug and 'snap-fitted' onto the top of the spark plug. There is a weather and temperature protective boot at the end of the spark plug wire covering the top of the spark plug.ĭepending on the design of the engine, these protective boots may be made entirely of rubber (see pictures below) or a combination of insulating metal over rubber. The exact location and number of spark plugs will vary with engine style, size and manufacturer. Most small engines only have one spark plug, twin-cylinder engines will have two spark plugs, four-cylinder engines will have four spark plugs.and so on. There will be one spark plug for each engine cylinder. Spark plugs are located on the front or top of the engine and have an approximately 1/4' diameter heavy wire (usually black) connected to the top of each one.

Lawn mower spark plug socket