Jeep 1997 Grand Cherokee Service Manual page 360

SHAFT
HOLDDOWN CLAMP
8D - 18 IGNITION SYSTEM
REMOVAL AND INSTALLATION (Continued)
Fig. 37 Distributor— 4.0L Engine—Typical
rotated. Distributor rotation is not necessary as all
ignition timing requirements are handled by the
powertrain control module (PCM).
The position of distributor determines fuel synchro-
nization only. It does not determine ignition timing.
NOTE: Do not attempt to modify this fork to attain
ignition timing.
REMOVAL—4.0L ENGINE
(1) Disconnect negative battery cable at battery.
(2) Disconnect coil secondary cable at coil.
(3) Remove distributor cap from distributor (2
screws). Do not remove cables from cap. Do not
remove rotor.
(4) Disconnect distributor wiring harness 3–way
connector from main engine harness.
(5) Remove cylinder number 1 spark plug.
(6) Hold a finger over the open spark plug hole.
Rotate engine at vibration dampener bolt until com-
pression (pressure) is felt.
(7) Slowly continue to rotate engine. Do this until
timing index mark on vibration damper pulley aligns
with top dead center (TDC) mark (0 degree) on tim-
ing degree scale (Fig. 38). Always rotate engine in
HOLDDOWN BOLT ROLL PIN GASKET WASHER DRIVE GEAR HOUSING CAMSHAFT POSITION SEN- WITH SLOT FORK SOR
direction of normal rotation. Do not rotate engine
backward to align timing marks.
Fig. 38 Align Timing Marks—4.0L Engine
(8) Remove distributor holddown bolt and clamp.
(9) Remove distributor from engine by slowly lift-
ing straight up.
(10) Note that rotor will rotate slightly in a coun-
terclockwise direction while lifting up the distributor.
The oil pump gear will also rotate slightly in a coun-
terclockwise direction while lifting up the distributor.
This is due to the helical cut gears on distributor and
camshaft.
(11) Note removed position of rotor during distrib-
utor removal. During installation, this will be
referred to as the Pre-position.
(12) Observe slot in oil pump gear through hole on
side of engine. It should be slightly before (counter-
clockwise of) the 11 o'clock position (Fig. 39).
(13) Remove and discard old distributor-to-engine
block gasket.
INSTALLATION
(1) If engine crankshaft has been rotated after dis-
tributor removal, cylinder number 1 must be
returned to its proper firing stroke. Refer to previous
REMOVAL Step 5 and Step 6. These steps must be
done before installing distributor.
(2) Check position of slot on oil pump gear. It
should be just slightly before (counterclockwise of)
the 11 o'clock position (Fig. 39). If not, place a flat
blade screwdriver into oil pump gear and rotate it
into proper position.
(3) Factory replacement distributors are equipped
with a plastic alignment pin already installed (Fig.
CRANKSHAFT DAMPER TIMING MARK VIBRATION
ZG