Jeep 1997 Grand Cherokee Service Manual page 355

ZG
REMOVAL AND INSTALLATION (Continued)
PLUG 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. 26). Never attempt to adjust
the gap by bending the center electrode.
Fig. 26 Setting Spark Plug Gap—Typical
SPARK PLUG GAP
4.0L 6–Cyl. Engine: .89 mm (.035 in).
5.2L V-8 Engines: 1.01 mm (.040 in).
5.9L V-8 Engines: .89 mm (.035 in).
PLUG INSTALLATION
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 elec-
trodes 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.
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) Tighten spark plugs to 35-41 N·m (26-30 ft.
lbs.) torque.
(3) Install spark plug cables over spark plugs.
GAUGE SPARK PLUG COIL MOUNT- ING BOLTS IGNITION COIL
IGNITION COIL—5.2L/5.9L ENGINES
The ignition coil is an epoxy filled type. If the coil
is replaced, it must be replaced with the same type.
REMOVAL
The coil is mounted to a bracket that is bolted to
the front of the right engine cylinder head (Fig. 27).
This bracket is mounted on top of the automatic belt
tensioner bracket using common bolts.
Fig. 27 Ignition Coil—5.2L/5.9L V-8Engines
(1) Disconnect the primary wiring from the igni-
tion coil.
(2) Disconnect the secondary spark plug cable from
the ignition coil.
WARNING:
ING BRACKET-TO-CYLINDER
BOLTS. THE COIL MOUNTING BRACKET IS UNDER
ACCESSORY
BRACKET IS TO BE REMOVED FOR ANY REASON,
ALL BELT TENSION MUST FIRST BE RELIEVED.
REFER TO THE BELT SECTION OF GROUP 7,
COOLING SYSTEM.
(3) Remove
bracket (two bolts).
INSTALLATION
(1) Install the ignition coil to coil bracket. If nuts
and bolts are used to secure coil to coil bracket,
tighten to 11 N·m (100 in. lbs.) torque. If the coil
mounting bracket has been tapped for coil mounting
bolts, tighten bolts to 5 N·m (50 in. lbs.) torque.
(2) Connect all wiring to ignition coil.
IGNITION COIL—4.0L ENGINE
The ignition coil is an epoxy filled type. If the coil
is replaced, it must be replaced with the same type.
COIL CONNEC-
IGNITION SYSTEM
DO NOT REMOVE THE COIL MOUNT-
HEAD
DRIVE BELT TENSION.
ignition coil from
TOR DRIVE ACCESSORY TENSIONER BELT
8D - 13
MOUNTING
IF THIS
coil mounting