Tools to Change the Spark Plugs on a 2002 Focus

Written by thomas west
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Changing the spark plugs on your 2002 Ford Focus may be one of the easiest -- if not one of the most overlooked -- tasks on the maintenance schedule of your car. Ford recommends changing the spark plugs every 100,000 miles. Even though spark plugs are made to withstand extreme heat and pressure, your engine may not be operating at peak efficiency with plugs that are overdue for a change. Ensure that you have the correct tools for this process on hand, to make a quicker job of it.


The spark plugs on a 2002 Ford Focus are nestled in the valley between the twin-overhead cams on top of the engine. Debris can become deposited into the valley, and may enter the cylinder when the spark plug is removed. This can be avoided by using an air gun attachment on an air compressor to spray all debris out of the valley, making a nice, clean environment for plug removal.

Plug Boot Removal

The spark plugs are connected to the car’s ignition system via four heavy-duty wires. Rubber boots on the ends of the wires keep water away from the plug tip, which could cause a rough-running or misfiring engine. An 8-mm socket attached to a 3-inch extension and a ratchet wrench is needed to remove the small boot retaining screws. The boot can be gently twisted off the plug once the electrical connector has been removed by hand.

Plug Removal

With the plug boot removed, the spark plug can then be twisted out of the cylinder head. A 5/8-inch spark plug wrench, a 3-inch extension and a ratchet wrench is needed for this task. Do not be tempted to use a standard, deep-well 5/8-inch socket, as it offers no protection to the ceramic top of the plug. Spark plug sockets have built-in padding, so that plugs can be removed without breakage.

Plug Installation

Before installation of the spark plugs, pack the inside of the spark plug boot with a non-conductive dielectric grease to seal out dirt, salt, water and other contaminants. Do not use regular grease, or the performance of the car’s ignition system may suffer. Check the inside of the boot after removal, as you may not need to add any addition grease if the boot is still packed with existing grease. A spark plug gapping tool is needed to ensure the replacement plugs are set to the correct gap. The gapping tool has a feeler gauge that is inserted between the plug electrode and the grounding strap. The notched end of the gapping tool is used to bend the grounding strap in the direction needed to obtain the proper gap.

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