Spark plug check and replacement
1. Spark plug replacement requires a spark plug socket, an extension and a ratchet. This socket is lined with a rubber grommet to protect the porcelain insulator of the spark plug and to hold the plug while you insert it into the spark plug hole. You will also need a wire-type feeler gauge to check and adjust the spark plug gap and a torque wrench to tighten the new plugs to the specified torque (see illustration).
30.1 Tools required for changing spark plugs
1 Spark plug socket — This will have special padding inside to protect the spark plugs porcelain insulator
2 Torque wrench — Although not mandatory, using this tool is the best way to ensure the plugs are tightened properly
3 Ratchet — Standard hand tool to fit the spark plug socket
4 Extension — Depending on model and accessories, you may need special extensions and universal joints to reach one or more of the plugs
5 Spark plug gap gauge — This gauge for checking the gap comes in a variety of styles. Make sure the gap for your engine is included
2. If you are replacing the plugs, purchase the new plugs, adjust them to the proper gap and then replace each plug one at a time.
3. Inspect each of the new plugs for defects. If there are any signs of cracks in the porcelain insulator of a plug, don’t use it.
4. Check the gap by inserting the wire gauge of the proper thickness between the electrodes at the tip of the plug (see illustration). The gap between the electrodes should be identical to that listed in this Chapter’s Specifications or on the VECI label. If the gap is incorrect, replace the spark plug.
30.4 Spark plug manufacturers recommend using a wire-type gauge when checking the gap — if the wire does not slide between the electrodes with a slight drag, spark plug replacement is required
Note: Do not adjust the gap on iridium spark plugs. Using a gapping tool on them could damage the iridium plating on the electrodes. These spark plugs are pre-gapped by the manufacturer.
5. Remove the engine cover (s) and disconnect any hoses or components that would interfere with access and move them out of the way.
6. Remove the bolts and detach each ignition coil assembly from the spark plugs (see illustration).
Note: On all V6 models, the upper intake manifold must be removed to gain access to the rear plugs (see V6 engine).
30.6 Remove the retaining bolt (A), disconnect the electrical connector (B) and detach the individual coils to reach the front spark plugs (four-cylinder models shown, V6 models similar)
7. If compressed air is available, blow any dirt or foreign material away from the spark plug area before proceeding (a common bicycle pump will also work).
Warning: Always wear eye protection when using compressed air!
8. Remove the spark plug (see illustration).
30.8 Because they are deeply recessed, the proper spark plug socket and an extension will be required when removing or installing the spark plugs
9. Whether you are replacing the plugs at this time or intend to re-use the old plugs, compare each old spark plug with those shown on the inside of the back cover to determine the overall running condition of the engine.
10. Apply a small amount of anti-seize compound to the spark plug threads (see illustration). It’s often difficult to insert spark plugs into their holes without cross-threading them. To avoid this possibility, fit a short piece of rubber hose over the end of the spark plug (see illustration). The flexible hose acts as a universal joint to help align the plug with the spark plug hole. Should the plug begin to cross-thread, the hose will slip on the spark plug, preventing thread damage. Tighten the plug to the torque listed in this Chapter’s Specifications.
30.10a A light coat of anti-seize compound applied to the threads of the spark plugs will keep the threads in the cylinder head from being damaged the next time the plugs are removed. Don’t get any near the lower threads
30.10b A section of rubber hose will aid in getting the spark plug threads started
11. Install the ignition coil.
12. Follow the above procedure for the remaining spark plugs, replacing them one at a time to prevent mixing up the spark plug