- 1). Check the new spark plugs for defects. Examine the porcelain part of the plug for cracks. If cracks are present, return the spark plugs for replacements.
- 2). Check the spark plugs' electrode gaps using the feeler gauge. Insert the wire part of the gauge that corresponds to the correct gap (0.043 inch) between the electrode and the plug head. If the gap is too large, bend the electrode slightly inward and check again. If it is too small, force the feeler wire into the gap until it fits easily.
- 3). Pull the wires off the spark plugs by grasping them near the boot and pulling them straight off, twisting as necessary. Mark the wires so you can replace them to the proper locations. An alternative is to change one spark plug at a time.
- 4). Insert the spark plug socket onto the plug and turn counterclockwise to remove. The plug will likely be very tight and might require you to gently tap the socket wrench to break it free.
- 5). Apply a thin coat of anti-seize compound to the threads of the new plugs. If you don't do this, future removal may be difficult or even impossible.
- 6). Insert the new plug into the hole and begin to turn it clockwise. Take care not to cross thread the spark plug's threads. If you feel resistance, unscrew the plug and begin again. To make things easier, attach a piece of three-eighths inch rubber tubing over the end of the plug, and use the tubing to start the plug into its socket. If you meet resistance, the tubing will slip, avoiding cross-threading.
Once the spark plug is fully seated, use the torque wrench to tighten it to 15 foot pounds of torque.
- 7). Attach the spark-plug wires again, ensuring that you attach the wires in the proper order. If you attach them incorrectly, the engine will misfire and lack power. If you change one spark plug at a time, you will be sure to avoid this problem. Make sure the wires are fully seated to prevent water from entering the plug socket.