Dodge ram truck 3500 1996 Service Manual page 399

BR IGNITION SYSTEM 8D - 1 7
DIAGNOSIS AND TESTING (Continued)
SPARK PLUG OVERHEATING
Overheating is indicated by a white or gray center
electrode Insulator that also appears blistered (Fig.
38). The Increase in electrode gap. will be consider­
ably in excess of 0.001 inch per 1000 miles of opera­
tion. This suggests - that a plug with a cooler heat
range rating should be used. Over advanced ignition
timing, detonation and cooling system malfunctions
can also cause spark plug overheating.
BLISTERED
WHITE OR
GRAY
COLORED
INSULATOR
J906D-16
Fig. 38 Spark Plug Overheating
R E M O V A L A N D I N S T A L L A T I O N
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. 39). Grasp the boot (not the cable) and
pull it off with a steady, even force.
SPARK PLUG BOOT *
PULLER
SPARK PLUG
CABLE A N D
BOOT
TWIST A N D PULL
Install cables into the proper engine cylinder firing
order (Fig. 40), (Fig. 41) or (Fig. 42).
o
FRONT
OF
ENGINE
CLOCKWISE ROTATION
1-6-5-4-3-2
J9314-80
Fig. 40 Engine Firing Order—3.9 L V-6 Engine
o
FRONT
O F
E N G I N E
CLOCKWISE ROTATION
1-8-4-3-6-5-7-2
J9314-79
Fig. 41 Engine Firing Order—5.2U5.9L V-8 Engines
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. I t 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 PLUG
958D-9
Fig. 39 Cable Removal