How to Change Spark Plugs for Mazda Carsby Contributing Writer; Updated June 12, 2017
Replacing the spark plugs on your Mazda car is not difficult. In fact, it's a rite of passage for the amateur mechanic. The most important thing to avoid is stripping the threads, which will cause major engine damage. The engine is made of aluminum and installing the spark plug at the wrong angle will destroy the threads in the spark plug hole. The threads consist of grooves in the hole that mate with those on the spark plug, except that the threads in the engine are softer and more easily damaged. The Mazda car has three spark plugs on the front and three spark plugs on the back of the engine.
Under The Hood:
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Check and adjust the gap on all four new Motorcraft AWSTF-32F, or equivalent, spark plugs, using a spark plug gap tool. Mazda recommends a gap from 0.042 to 0.046 inches on the 2.5-liter's spark plugs.
Trace a spark plug wire toward the driver's side of the engine until you reach the spark plug's rubber boot. Pull upward on the spark plug boot with a slight twisting motion to remove the spark plug wire from the spark plug,
Inspect the removed wire for any visual abnormalities, such as: cracking, peeling, splitting or excessive age. If any defects exist, replace all four wires while replacing the spark plugs. Keep in mind; only remove one spark plug wire at a time to retain the correct ignition firing order.
Remove the spark plug using a ratchet and spark plug socket. Pull the old plug from the spark plug socket and press the new plug into the socket until the rubber insert inside the socket holds the plug in place.
Hand-tighten the spark plug into the engine, using the spark plug socket. Attach a torque wrench to the spark plug socket and tighten the spark plug to 7 to 14 foot-pounds.
Apply a thin coat of dielectric grease to the inside of the spark plug wire boot and press it onto the spark plug until it clicks into place.
Repeat Steps 2 through 6 until you replace all four old spark plugs with new ones.
Items you will need
4 new Motorcraft AWSTF-32F, or equivalent, spark plugs
Spark plug gap tool
Spark plug wire set (optional)
Spark plug socket
Install spark plugs in your MPV
Twist and pull the spark plug wire from the leftmost spark plug on the front of the engine. Grasp the spark plug wire by the "boot" or the end of the wire that cups the plug. Avoid pulling on the wire itself.
Place the spark plug socket on the spark plug. Turn the wrench counterclockwise to remove the spark plug. Unscrew the plug until it is fully removed from the engine.
Install the new spark plug by carefully placing it in the hole by hand. Turn the spark plug clockwise, but do so only gently by hand. Ensure that the spark plug screws in gently and naturally. Stop turning it at the first sign of major resistance. Check to make sure that you have not stripped the threads. Move on to the next step only when you're sure that you've positioned the plug at the correct angle and have it threaded most of the way in.
Position the spark plug socket over the spark plug and tighten it with the ratchet. Avoid tightening it too much. It will offer increased resistance for about half a turn as the metal washer on the plug is compressed. Once it is good and snug, stop there.
Replace the wire by handling the boot of the spark plug wire. Listen for a "click" that indicates correct installation.
Use this procedure for the remaining two plugs on the front and the three plugs on the back of the engine. Remove and replace one plug at a time, to ensure that you don't mix up the wires.
Items you will need
Spark plug socket and wrench
Rear Rotor Spark Plugs
Jack up the car, and remove the driver's side front tire. Once the car is up, place a jack stand on the frame of the car, just in case the jack should fail.
Reach backward through the wheel well toward the back of the motor, and you'll feel the spark plug wires. Remove the wires by pulling on them.
Use the wrench to turn counterclockwise until the first spark plug is loose enough to turn by hand. When you remove the plugs, set them aside in a way that's easy to remember where they came from. The plugs are in a specific order, and have to remain that way.
Place a small dab of anti-seize to the threads of the spark plug, and screw them back into place. Take note of what the spark plug is marked with. All RX8 spark plugs are marked with a "T" or an "L." The "T" stands for trailing, while the "L" stands for leading. It's of great importance that these spark plugs go in the intended location.
Replace the spark plug wires by putting them over the plugs, and pushing down until they form a solid bond.
Front Rotor Spark Plugs
Behind the driver's side wheel, remove the bolt that secures the rubber splash guards in place. Once the bolt is removed, use a flat-head screwdriver to remove the washer holding the guard on. Be gentle, as this is fragile. If it won't come off, give it a little twist.
Reach forward, toward the front of the motor and you'll be able to reach the front spark plugs. Remove the plugs and twist them with a wrench until they are loose enough to turn by hand.
Set the plugs aside in a way that allows you to remember where exactly each plug came from. Remember, the new plugs have to remain in the same order.
Place a dab of anti-seize on the new plugs and then insert the plugs into the holes created by removing the old ones. Take great care to put the plugs in the correct holes. Replace the plug wires.
Work in reverse order to re-install the splash guard.
Mount the driver's side tire back onto the hub. Tighten the lug nuts.
Items you will need
Pop the hood and allow the engine to cool. Locate the engine cove and the intake manifold.
Loosen the three bolts that hold the dust cover in place. Use a 10mm socket to remove them. Gently turn the bolts, so they do not get damaged. Remove the dust cover from the engine.
Use the 3/8 socket to loosen the intake manifold. Loosen the vacuum hoses but do not remove the vacuum hoses. Carefully remove the manifold and set it on the side of the engine. If a gasket gets turned in the process, replace it with a new one when you put things back together. These gaskets are hard to find in auto parts stores, so you may have to find them at a Mazda dealership.
Find the back spark plug wires and remove them. Grab the tip, or boot, of the wire and turn 180 degrees to the right and left. Pull the wire of the spark plug. Replace each spark plug one at a time. If the spark plug wires are placed on the wrong spark plug, it damages the engine.
Place the 5/16 socket on the spark plug and loosen the spark plug. Pull the plug out of the well once it clears the threads.
Remove any debris or dirt from the wire boot and spark plug well. Lightly scrub them with a wire brush.
Apply a layer of anti-seize compound to the thread of the spark plug and insert the plug into the well. First tighten the plug by hand and then use the socket to tighten the plug 1/4 turn.
Replace the wire. Turn the wire 180 degrees in each direction until you hear or feel a click. Continue the process with the other wires on the back of the engine.
Replace the intake manifold gaskets if needed. Place the manifold back on the engine and bolt it in place. Return the dust cover to it's place.
Move to the front of the engine and repeat Steps 4 through 8 for the front spark plugs.
Items you will need
3/8 socket wrench
5/16 or metric version socket