Spark Plugs

Changing your spark plugs

by Conrad & Judy Kreuter

Changing spark plugs should be done as part of the annual routine maintenance tune up of your motor. Spark plugs ignite the fuel air mixture within the cylinders to produce the power required to propel the boat. Because they are in a harsh environment consistently exposed to high heat and explosive forces during the combustion process, they will wear out over the season. Malfunctioning engines expose spark plugs to even worse conditions.

Changing spark plugs is not a difficult task. If you are changing them as part of routine maintenance simply replace with the same type as originally installed in the engine. Only use those spark plugs recommended by the engine manufacturer.

Disconnect the spark plug wire connected to the top of the plug by twisting and gently pulling the cap off the plug. Using a suitable wrench, remove each plug. Keep them in order so that you know which plug came out of each cylinder. When you have removed all the plugs, compare the condition of each. They should appear similar. If one appears different than all the rest, you may have a problem with that cylinder. Unless you are going to fix the engine yourself, it is best to put the plugs back into their respective cylinders and let a professional take a look at the engine. Valuable troubleshooting information will be lost by not leaving the old spark plugs in their original positions.

If the old spark plugs look normal, simply replace with the new plugs. Tighten spark plugs to the recommended torque specifications. Proper torque is crucial to heat transfer and prevention of combustion gas leakage. Too little torque or too much torque can result in premature plug failure or misfire.