Spark Plug: Service and Repair

SPARK PLUG SERVICE
Failure to route the cables properly could cause the radio to reproduce ignition noise, cross ignition of the spark plugs or short circuit the cables to ground.

SPARK PLUG REMOVAL
Remove the spark plugs and examine them for burned electrodes and fouled, cracked or broken porcelain insulators.

Keep plugs arranged in the order in which they were removed from the engine. An isolated plug displaying an abnormal condition indicates that a problem exists in the corresponding cylinder.

Always remove the spark plug cable by grasping the top of the spark plug insulator, turning the boot 1/2 turn and pulling straight up in a steady motion.

Spark plugs that have low mileage may be cleaned and reused if not otherwise defective, carbon or oil fouled.

CAUTION: Special care should be used when installing spark plugs in the cylinder head spark plug wells. Re sure the plugs do not drop into the wells, damage to the electrodes can occur.

1. Remove the spark plug using a quality socket with a rubber or foam insert.
2. Inspect the spark plug condition. SEE Testing and Inspection/Spark Plug Condition.

Fig. 4 Setting Spark Plug Electrode Gap:

SPARK PLUG GAP ADJUSTMENT
Check the spark plug gap with a gap gauge. If the gap is not correct, adjust it by bending the ground electrode Fig. 4.

SPARK PLUG CLEANING
The plugs may be cleaned using commercially available spark plug cleaning equipment. After cleaning, file the center electrode flat with a small point file or jewelers file before adjusting gap.

CAUTION: Never use a motorized wire wheel brush to clean the spark plugs. Metallic deposits will remain on the spark plug insulator and will cause plug misfire.

SPARK PLUG INSTALLATION
1. To avoid cross threading, start the spark plug into the cylinder head by hand.

CAUTION: Over tightening can cause distortion and change spark plug gap.

2. Tighten spark plugs to 28 Nm (20 ft lb) torque.
3. Install spark plug insulators over spark plugs. Ensure the top of the spark plug insulator covers the upper end of the spark plug tube.

SPARK PLUG TUBES
The spark plugs tubes are pressed into the cylinder head. Sealant is applied to the end of the tube before installation. For engine information, SEE Engine.