How to Replace Spark Plugs on a Jeep Liberty

by John Stevens J.D.
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First produced in 2002, the Jeep Liberty was available with either a four or six cylinder engine, and used a single spark plug for each cylinder. The sole responsibility of the Liberty’s spark plugs is to ignite the compressed air/fuel mixture within the engine’s cylinders. Spark plugs are exposed to tremendous pressure and temperatures; therefore, they have a finite lifespan. As a spark plug’s ability to produce a spark diminishes, so too does the engine’s power output and fuel efficiency.

Step 1

Adjust the gap on the replacement spark plugs. At the tip of the spark plug that enters the cylinder head is a small metal piece shaped like a hood. The tip of the hook hovers just above a metal circle on the bottom of the spark plug. These two metal pieces are called the electrodes. The distance between these pieces is referred to as a “gap.” The gap determines the length of the spark when the spark plug fires. Before the new plugs can be installed, the gap must be adjusted to .035-inch with a feeler gauge. Select the blade of the feeler gauge which represents .035-inch, then insert the blade between the two metal pieces. Bend the hook-shaped piece toward the plug until the proper gap is reached.

Step 2

Remove the spark plug wire for any one spark plug. There is no particular order by which the plugs must be replaced. However, it is important to replace only one spark plug at a time to avoid crossing the spark plug wires. Grasp the rubber base of the spark plug wire, where the wire connects to the spark plug, then firmly pull the wire off of the plug. Do not pull the actual spark plug wire, as the wire may pull out of its rubber base. If the wire is stubborn, twist the base of the wire before pulling it off of the spark plug.

Step 3

Remove the spark plug with either a 10 or 13 mm spark plug socket, depending on the engine, attached to a socket wrench by turning the spark plug in a counterclockwise direction.

Step 4

Insert a replacement spark plug into the cylinder head, then twist the plug into the cylinder head by hand until it cannot be twisted further with reasonable effort. Tighten the spark plug into the cylinder head with the spark plug socket by 1/4 of a turn. Take care not to over tighten the plug, which may cause the it to break.

Step 5

Press the rubber base of the spark plug wire onto the top of the replacement spark plug until the wire clicks into place. Follow the same procedure for the remaining spark plugs.

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