Replacing Spark Plugs

If opening your car's glove compartment rates as your high water mark for mechanical achievement, this article is for you. In it you'll learn how to change your car's spark plugs--necessary as part of regular car maintenance. And while it won't elevate you to mechanical high priest status, it will provide you with a heady sense of engine-intrepidity and save you cash on maintenance costs.

Once you know what to do and what to look for, changing your spark plugs will seem as easy as changing a flat or replacing an air filter. Depending on your vehicle and experience, this task may take you no longer than 40-60 minutes.

Needed Tools

Before you can begin any task, you must have the necessary tools. Otherwise, you'll spend more time hunting for what you need than you'll spend actually changing your spark plugs.

You may need:

  • 3/8 inch ratchet
  • Ratchet extensions
  • Spark plug socket
  • Spark plug gap gauge
  • 3/8 inch swivel socket
  • Compressed air canister

Step-by-Step Procedures

  1. Before you begin grabbing, pulling, and ratcheting, make sure that the engine is cold and that you have the correct spark plugs for your vehicle. Installing incorrect plugs can corrupt the engine. Ask your auto supply store for the correct application or check your car owner manual.
  2. Disconnect the spark plug wire from the plug. Do not yank by the wire like you're extracting carrots from a garden, but by tugging on the boot. If the boot resists, try twisting left and right to loosen. Be sure to change each plug one at a time, especially if this is your first spark plug venture; otherwise you risk trying to guess which plug matches with which wire.
  3. Before removing the plug, put on eye protection and clean the spark plug area with the compressed air canister. This will prevent any dirt from falling into the cylinder when the spark plug is detached. Dirt to an engine is the equivalent of a cold germ to a human.
  4. Using the spark plug ratchet, begin unscrewing the plug by turning counterclockwise. Once the plug is loose enough, finish by removing it by hand.
  5. Before inserting the new spark plug into the valve, use the gap gauge to calculate a proper gap. Consult your vehicle's user manual or the specifications decal under the hood for your car's exact gap size. Creating the correct gap is very important. A gap that is too small or too wide will fleece your engine of power and fuel efficiency.
  6. To gap your plug, insert the gauge in between the bottom of the plug (inner electrode) and the hook (outer electrode), which resembles a small awning. Depending on your vehicle's specifications you will then either need to bend the hook lower or higher.
  7. Before inserting the new spark plug, double-check that the cylinder's threads are free of dirt. Otherwise the spark plug will not insert properly. If you feel ambitious lubricate the threads with a never-seize compound so as to assure easy removal next time it comes to switching the plugs.
  8. Begin screwing in the spark plug by hand until it's firmly secure. Finish tightening with the ratchet.
  9. Reattach the plug wire, using a twisting motion to properly position the boot above the plug. When you hear a click you'll know the wire has precisely connected with the spark plug.
  10. Repeat these same steps with the other spark plugs, replacing each plug one at a time.
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