Spark plug cables. Spark plugs

Spark plug cables

CAUTION: When disconnecting a high voltage cable from a spark plug or from the distributor cap, twist the rubber boot slightly (1/2 turn) to break it loose (Fig. 20). Grasp the boot (not the cable) and pull it off with a steady, even force.

Fig. 20 Cable Removal

1 - SPARK PLUG CABLE AND BOOT

2 - SPARK PLUG BOOT PULLER

3 - TWIST AND PULL

4 - SPARK PLUG

Install cables into the proper engine cylinder firing order (Fig. 21).

Fig. 21 Engine Firing Order-5.2/5.9L V-8 Engine

When replacing the spark plug and coil cables, route the cables correctly and secure in the proper retainers. Failure to route the cables properly can cause the radio to reproduce ignition noise. It could also cause cross ignition of the plugs or short circuit the cables to ground.

When installing new cables, make sure a positive connection is made. A snap should be felt when a good connection is made between the plug cable and the distributor cap tower.

Spark plugs

REMOVAL

On 3.9L V-6 and 5.2/5.9L V-8 engines, spark plug cable heat shields are pressed into the cylinder head to surround each cable boot and spark plug (Fig. 22).

Fig. 22 Heat Shields-3.9/5.2/5.9L Engines

1 - AIR GAP

2 - SPARK PLUG BOOT HEAT SHIELD

If removal of the heat shield(s) is necessary, remove the spark plug cable and compress the sides of shield for removal. Each shield is slotted to allow for compression and removal. To install the shields, align shield to machined opening in cylinder head and tap into place with a block of wood.

4.7L V-8 Engine: Each individual spark plug is located under each ignition coil. Each individual ignition coil must be removed to gain access to each spark plug. Refer to Ignition Coil Removal/Installation.

(1) Except 4.7L Engine: Prior to removing spark plug, spray compressed air around spark plug hole and area around spark plug. This will help prevent foreign material from entering combustion chamber.

(2) 4.7L V-8 Engine: Prior to removing spark plug, spray compressed air around base of ignition coil at cylinder head. This will help prevent foreign material from entering combustion chamber.

(3) Remove spark plug from cylinder head using a quality socket with a rubber or foam insert. If equipped with a 4.7L V-8 engine, also check condition of coil o-ring and replace as necessary.

(4) Except 4.7L: Always remove spark plug or ignition coil cables by grasping at the cable boot (Fig.

20). Turn the cable boot 1/2 turn and pull straight back in a steady motion. Never pull directly on the cable. Internal damage to cable will result.

(5) Inspect spark plug condition. Refer to Spark Plug Conditions.

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.

GAP ADJUSTMENT

Check the spark plug gap with a gap gauge tool. If the gap is not correct, adjust it by bending the ground electrode (Fig. 23). Never attempt to adjust the gap by bending the center electrode.

Fig. 23 Setting Spark Plug Gap-Typical

1 - GAUGE

2 - SPARK PLUG

INSTALLATION

CAUTION: The 4.7L V-8 engine is equipped with copper core ground electrode spark plugs. They must be replaced with the same type/number spark plug as the original. If another spark plug is substituted, pre-ignition will result.

Special care should be taken when installing spark plugs into the cylinder head spark plug wells. Be sure the plugs do not drop into the plug wells as electrodes can be damaged.

Always tighten spark plugs to the specified torque.

Over tightening can cause distortion resulting in a change in the spark plug gap or a cracked porcelain insulator.

Except 4.7L Engine: When replacing the spark plug and ignition coil cables, route the cables correctly and secure them in the appropriate retainers.

Failure to route the cables properly can cause the radio to reproduce ignition noise. It could cause cross ignition of the spark plugs or short circuit the cables to ground.

(1) Start the spark plug into the cylinder head by hand to avoid cross threading.

(2) Except 4.7L Engine: Tighten spark plugs to 35-41 N*m (26-30 ft. lbs.) torque.

(3) Except 4.7L Engine: Install spark plug cables over spark plugs.

(4) 4.7L V-8 Engine: Tighten spark plugs to 27 N*m (20 ft. lbs.) torque.

(5) 4.7L V-8 Engine: Before installing coil(s), check condition of coil o-ring and replace as necessary.

To aid in coil installation, apply silicone to coil o-ring.

(6) 4.7L V-8 Engine: Install ignition coil(s). Refer to Ignition Coil Removal/Installation.