Spark Plug


Spark Plug Removal

Spark plug replacement is part of the preventative maintenance program for all vehicles. The recommended replacement interval depends on a number of factors but ranges from 20,000 to 100,000 miles (32,000 to 160,000 km).

Removal of an engine's spark plugs is pretty straightforward.

  • Remove the cables from each plug, being careful not to pull on the cables. Instead, grasp the boot and gently twist it off (To save time and avoid confusion later, use masking tape to mark each of the cables with the number of the plug it attaches to).
Grab hold of the boot and twist while pulling it off a spark plug. Reprinted with permission.
  • Using a spark plug socket and ratchet, loosen each plug a couple of turns.
  • Once the spark plugs are loose, use compressed air to blow dirt away from the base of the plugs.
  • Then, remove the plugs making sure to remove the gasket as well if applicable.
  • When the spark plugs are removed, they should be set in order so the technician can identify the spark plug from each cylinder.

Spark Plug Installation

Regardless of what other tools may need to be used, a spark plug socket is essential for plug removal and installation.

  • Wipe dirt and grease from the plug seats with a clean cloth.
  • Be sure the gaskets on gasketed plugs are in good condition and properly placed on the plugs. If reusing a spark plug, install a new gasket on it. Be sure that there is only one gasket on each plug.
  • Adjust the air gap as needed.
  • Check the service manual to see if anti-seize compound should be applied to the plug's threads. If it should, do so now.
  • Install the plugs and tighten them with your hand. If the plugs cannot be installed easily by hand, the threads in the cylinder head may need to be cleaned with a thread-chasing tap. Be especially careful not to cross-thread the plugs when working with aluminum heads.
  • Tighten the plugs with a torque wrench, following the vehicle manufacturer's specifications, or refer to the values listed in the table below.