How to Change the Spark Plugs on a 1998 Mountaineer

The 1998 Mercury Mountaineer is powered by either a 4.0-liter V-6 or a 5.0-liter V-8. In either case, the procedure for changing the plugs remains the same. It is not a challenging job since you can access the plugs through the front wheel wells. The O.E.M. plug is an Autolite XP140 Iridium/Platinum, however, you can replace them with normal copper plugs with the only drawback being reduced service life of the plugs.

Instructions

1

Remove the plastic splash shield in each front fender well using a socket and ratchet. With the splash shield removed you can see and get to the spark plug wires and plugs.

2

Pull the wire off the first cylinder by installing the boot remover tool and twisting the spark plug boot to the left and right to break it loose. Pull it straight off. Use the long extension with a universal and the spark plug socket to reach the plug. Turn the spark plug counterclockwise to remove it. Replace one plug at a time, to avoid mixing up the wires.

3

Gap the spark plug to .054 inch, using the gapping tool. Install the spark plug by hand to prevent cross-threading the plugs. Torque the plug to 1 to 14 foot-pounds, using a torque wrench -- do not over-tighten.

4

Snap the spark plug boot on the spark plug. Repeat the process for each plug. Re-install the splash shields in the fender wells.