How Do You Replace Spark Plugs?


To replace spark plugs, remove each spark plug wire by pulling the caps, and then unscrew each of the plugs and remove them. Next, use a plug-gapping tool to properly gap the new plugs. Finally, screw in the new plugs and attach the plug wires.

Before removing the old plugs, allow your vehicle engine to cool for three to four hours, which in turn allows the plugs to cool so they are not too hot to touch. After removing the plugs, check your vehicle manual or repair guide to find the correct gap for your new plugs, and then gap them to the required specifications. Be careful not to allow dirt or other substances to fall into the engine in the areas exposed by plug removal.

Before discarding the old plugs, examine them for signs of mechanical issues with your vehicle, such as dark coloring, which sometimes indicates a vacuum leak, low compression, too large a spark plug gap or overly rich fuel mixture. Apply a dielectric silicone compound on the inside of the new plugs' wire boots to make future removal easier. Use a spark-plug socket-and-torque wrench to screw in the new plugs, and then connect the plugs to the wires.