Inspect the electrodes and ceramic insulator.
Burned or worn electrodes may be caused by:
Fouled plug may be caused by:
Do not adjust the gap of platinum tip plugs; replace the spark plug if the gap is out of specification. The gap should be 0.039-0.043 in. (1.0-1.1mm).
- Replace the plug at the specified interval or if the center electrode is rounded.
- Apply a small quantity of anti-seize compound to the plug threads, and screw the plugs into the cylinder head finger-tight.
Removal & Installation
When removing spark plugs, work on them one at a time to avoid confusion. Do not remove the plug wires at the same time, unless you number them, they may become mixed up. Take a minute before you begin and number the wires with tape.
- Disconnect the negative battery cable, and if the vehicle has been run recently, allow the engine to thoroughly cool.
- Carefully twist the spark plug wire boot to loosen it, then pull upward and remove the boot from the plug. Be sure to pull on the boot and not on the wire, otherwise the connector located inside the boot may become separated.
Using compressed air, blow any water or debris from the spark plug well to assure that no harmful contaminants are allowed to enter the combustion chamber when the spark plug is removed. If compressed air is not available, use a rag or a brush to clean the area.
NOTERemove the spark plugs when the engine is cold to prevent damage to the threads. If the plugs is hard to remove, apply a few drops of a penetrating lubricant to the area around the base of the plug, and allow it sit for a few minutes to work.
Using a spark plug socket that is equipped with a rubber insert to hold the plug, turn the spark plug counterclockwise to loosen and remove the spark plug from the bore.
WARNINGIt is advisable not to use a flexible extension on the socket when removing or installing spark plugs. This may allow a shear force to be applied to the plug. A shear force could break the plug off in the cylinder head, leading to costly and frustrating repairs.
- Inspect the spark plug boot for damage and replace if necessary
- Check and adjust the spark plug gap
- Carefully thread the plug into the bore by hand. If resistance is felt before the plug is almost completely threaded, back the plug out and begin threading again.
- Carefully tighten the spark plug to 13 ft. lbs. on 3.0L engines or 18 ft. lbs. on 3.3L engines.
- Apply a small amount of silicone dielectric compound to the end of the spark plug lead or inside the spark plug boot to prevent sticking, then install the boot to the spark plug and push until it clicks into place.