Chrysler Pacifica. Manual — part 672
(2) To replace spark plug tube seals:
(a) Using a suitable pry tool, carefully remove
tube seals.
(b) Position new seal with the part number on
seal facing cylinder head cover.
(c) Install seals using Special Tool MD-998306
(Fig. 43).
(3) Install cylinder head cover bolts and tighten to
12 N·m (105 in. lbs.).
(4) Install the ground strap retaining bolt to the
cylinder head cover.
(5) Install the wire harness track retaining nuts
(Fig. 41).
(6) Install the ignition coils. Tighten mounting
screws to 6.7 N.m (60 in. lbs.) (Fig. 41).
(7) Connect the ignition coil electrical connectors
(Fig. 41).
(8) Install upper intake manifold (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE
MANIFOLD
-
INSTALLATION).
(9) Connect negative battery cable.
VALVES & SEATS -INTAKE/
EXHAUST
DESCRIPTION
Valves are made of highly heat-resistant steel and
are chrome plated to prevent stem scuffing. The
intake valve is a one-piece forging, while the exhaust
valve has a forged head with a welded stem for lock
groove hardenability. The four valves (two intake and
two exhaust) employ a three-groove lock design to
help facilitate valve rotation.
OPERATION
The intake valve allows the air/fuel mixture to
enter the combustion chamber. The exhaust valve
allows the burned air/fuel mixture to exit the com-
bustion chamber. Also, the intake and exhaust valves
seal the combustion chamber during the compression
and power strokes.
STANDARD PROCEDURE - VALVE AND VALVE
SEAT REFACING
The valve face and valve seat angles are shown in
(Fig. 44).
VALVES
(1) Inspect the remaining margin after the valves
are refaced (Refer to 9 - ENGINE - SPECIFICA-
TIONS).
VALVE SEATS
(1) When refacing valve seats, it is important that
the correct size valve guide pilot be used for reseat-
ing stones. A true and complete surface must be
obtained.
(2) Measure the concentricity of valve seat using
dial indicator. Total runout should not exceed 0.051
mm (0.002 inch.) total indicator reading.
Fig. 43 Spark Plug Tube Seal Installation
1 - SPECIAL TOOL MD-998306
2 - SPARK PLUG TUBE SEAL
Fig. 44 Intake and Exhaust Valves
1 - MARGIN
2 - FACE
3 - STEM
4 - VALVE SPRING RETAINER LOCK GROOVES
Fig. 45 Valve Face & Seat
1 - SEAT WIDTH
2 - FACE ANGLE
3 - SEAT ANGLE
4 - SEAT CONTACT AREA
CS
ENGINE 3.5L
9 - 43
COVER CYLINDER HEAD - RIGHT (Continued)
(3) Inspect the valve seat with Prussian blue to
determine where the valve contacts the seat. To do
this, coat valve seat LIGHTLYwith Prussian blue
then set valve in place. Rotate the valve with light
pressure. If the blue is transferred to the center of
valve face, contact is satisfactory. If the blue is trans-
ferred to top edge of valve face, then lower valve seat
with a 15 degree stone. If the blue is transferred to
the bottom edge of valve face, then raise valve seat
with a 65 degree stone.
NOTE: Valve seats which are worn or burned can
be reworked, provided that correct angle and seat
width are maintained. Otherwise cylinder head must
be replaced.
(4) When seat is properly positioned the width of
the intake seats should be 0.75 to 1.25 mm (0.0296 to
0.0493 in.) and exhaust seats should be 1.25 to 1.75
mm (0.049 to 0.069 in.) (Fig. 45).
VALVE AND SPRING INSTALLED HEIGHT
(1) Coat valve stems with clean engine oil and
insert them in cylinder head.
(2) If valves or seats have been refaced, check
valve tip height (A) (Fig. 46). If valve tip height is
greater than 43.65 mm (1.7185 in.) intake or 45.98
mm (1.8102 in.) exhaust, grind valve tip until within
specifications. Make sure measurement is taken from
cylinder head surface to the top of valve stem.
(3) Install valve seal/spring seat assembly over
valve guides on all valve stems (Fig. 48). Ensure that
the garter spring is intact around the top of the rub-
ber seal.
(4) Place valve spring (color-coded end facing up )
(Fig. 47) and valve retainer into position on spring
seat (Fig. 46).
(5) Compress valve springs with valve spring com-
pressor C-3422-D and adapter 6526 (Refer to 9 -
ENGINE - SPECIAL TOOLS), install locks and
release tool.
(6) If valves and/or seats are refaced, measure the
installed height of springs (Fig. 46).. Measurements
are taken from top of spring seat to the bottom sur-
face of spring retainer. If height is greater than 38.75
mm (1.5256 in.), install a 0.762 mm (0.030 in.) spacer
in head counterbore under the valve spring seat to
bring spring height back within specification.
Fig. 46 Checking Valve Tip Height and Valve Spring
Installed Height
1 - SPRING RETAINER
2 - GARTER SPRING
3 - VALVE SPRING SEAT TOP
4 - CYLINDER HEAD SURFACE
Fig. 47 Valve Spring Identification
1 - YELLOW OR WHITE DYE
2 - ORANGE DYE
Fig. 48 Valve Seal and Spring—Installation
1 - VALVE
2 - VALVE RETAINING LOCKS
3 - VALVE SPRING RETAINER
4 - VALVE SPRING
5 - VALVE SEAL AND VALVE SPRING SEAT ASSEMBLY
9 - 44
ENGINE 3.5L
CS
VALVES & SEATS -INTAKE/EXHAUST (Continued)
REMOVAL
(1) Remove cylinder head(s) (Refer to 9 - ENGINE/
CYLINDER HEAD - REMOVAL).
(2) Remove rocker arm assembly (Refer to 9 -
ENGINE/CYLINDER
HEAD/ROCKER
ARM
/
ADJUSTER ASSY - REMOVAL).
(3) Remove valve spring(s) (Refer to 9 - ENGINE/
CYLINDER HEAD/VALVE SPRINGS - REMOVAL).
(4) Before removing valve, remove any burrs
from valve stem lock grooves to prevent dam-
age to the valve guides. Identify valves to insure
installation in original location.
(5) Remove valve(s) from cylinder head.
CLEANING
(1) Clean
all
valves
thoroughly
and
discard
burned, warped and cracked valves.
INSPECTION
INSPECTION - VALVES
(1) Measure valve stems for wear (Fig. 49) approx-
imately 60 mm (2.36 in.) below the valve lock
grooves.
(2) Compare measurement to specifications, (Refer
to 9 - ENGINE - SPECIFICATIONS).
NOTE: Valve stems are chrome plated and should
not be polished (Fig. 49).
INSPECTION - VALVE GUIDES
(1) Measure valve stem-to-guide clearance as fol-
lows:
(2) Install valve into cylinder head so it is 15 mm
(0.590 inch.) off the valve seat. A small piece of hose
may be used to hold valve in place.
(3) Attach dial indicator Tool C-3339 to cylinder
head and set it at right angle of valve stem being
measured (Fig. 50).
(4) Move valve to and from the indicator.
(5) Note dial indicator reading and compare to
engine specifications. (Refer to 9 - ENGINE - SPEC-
IFICATIONS)
NOTE: Replace cylinder head if stem-to-guide clear-
ance exceeds specifications, or if guide is loose in
cylinder head.
Fig. 49 Intake and Exhaust Valves
1 - MARGIN
2 - FACE
3 - STEM
4 - VALVE SPRING RETAINER LOCK GROOVES
Fig. 50 Measuring Valve Guide Wear
CS
ENGINE 3.5L
9 - 45
VALVES & SEATS -INTAKE/EXHAUST (Continued)
INSTALLATION
(1) Coat valve stems with clean engine oil and
insert them in cylinder head.
(2) If valves or seats have been reground, check
valve tip height (A) (Fig. 51). If valve tip height is
greater than 43.65 mm (1.7185 in.) intake or 45.98
mm (1.8102 in.) exhaust, grind valve tip until within
specifications. Make sure measurement is taken from
cylinder head surface to the top of valve stem.
(3) Install new valve stem seals.
(4) Install valve springs (Refer to 9 - ENGINE/
CYLINDER HEAD/VALVE SPRINGS - INSTALLA-
TION).
(5) Install cylinder head(s) (Refer to 9 - ENGINE/
CYLINDER HEAD - INSTALLATION).
ROCKER ARM SHAFT/
ROCKER ARM / LASH
ADJUSTER
DESCRIPTION
DESCRIPTION - ROCKER ARM
Rocker arms are made of light weight permanent
mold aluminum alloy with a roller type follower oper-
ating against the camshaft (Fig. 52). The valve actu-
ating end of the rocker arms are machined to retain
hydraulic lash adjusters, eliminating the need for
manual valve lash adjustment.
DESCRIPTION - ROCKER ARM SHAFTS
The rocker arm shafts (Fig. 53) are tubular steel
and are supported by several forged aluminum alloy
pedestals, which are fastened to the cylinder head.
Four shafts are used, one for each intake and
exhaust rocker arm bank on each cylinder head. The
shafts are hollow to provide a duct for lubricating oil
flow from the cylinder head to the valve mechanisms.
One hollow dowel per pedestal is used to locate the
pedestal to the cylinder head, orient the exhaust
rocker shaft, and serve as a cam bearing oil feed pas-
sage.
Fig. 51 Checking Valve Tip Height and Valve Spring
Installed Height
1 - SPRING RETAINER
2 - GARTER SPRING
3 - VALVE SPRING SEAT TOP
4 - CYLINDER HEAD SURFACE
Fig. 52 Rocker Arm Assembly
1 - RETAINER
2 - SWIVEL PAD
3 - ROLLER
Fig. 53 Rocker Arms and Shafts
9 - 46
ENGINE 3.5L
CS
VALVES & SEATS -INTAKE/EXHAUST (Continued)
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