Chrysler Dodge Caravan 2002 Manual page 1307

9 - 106 ENGINE 3.3/3.8L
INTAKE/EXHAUST VALVES & SEATS (Continued)
(2) Measure the concentricity of valve seat using
dial indicator (Fig. 31). Total runout should not
exceed 0.051 mm (0.002 in.) total indicator reading.
Fig. 31 Measurement of Valve Seat Runout
1 - DIAL INDICATOR
(3) Inspect the valve seat using 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, lower valve seat with
a 15 degree stone. If the blue is transferred to the
bottom edge of valve face raise valve seat with a 65
degrees 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
intake and exhaust seats should be 1.50–2.00 mm
(0.059–0.078 in.) (Fig. 28).
(5) After grinding the valve seats or faces, install
the valve in cylinder head and check valve installed
height by measuring from valve tip to spring seat
(Fig. 32). Remove valve from cylinder head and grind
valve tip until within specifications. Check valve tip
for scoring. The tip chamfer should be reground (if
necessary) to prevent seal damage when the valve is
installed.
(6) Check the valve spring installed height after
refacing the valve and seat (Fig. 32).If valves
and/or seats are
installed height of springs (Fig. 32), make sure
measurements are taken from top of spring
seat to the bottom surface of spring retainer. If
height is greater than specifications, install a
reground, measure
0.794 mm (0.0312 in.) spacer in head counter-
bore to bring spring height back within specifi-
cations.
Fig. 32 Checking Valve and Spring Installed Height
1 - SPRING RETAINER
2 - VALVE INSTALLED HEIGHT* - 48.1–49.7 mm (1.89–1.95 in.)
3 - CYINDER HEAD SURFACE
4 - SPRING INSTALLED HEIGHT* - 41.1–42.7 mm (1.61–1.68 in.)
*(MEASURED FROM TOP OF SPRING SEAT)
REMOVAL
(1) With cylinder head removed, compress valve
springs using
C-3422-D with adapter 8464 (Refer to 9 - ENGINE -
SPECIAL TOOLS).
(2) Remove valve retaining locks.
(3) Slowly
Remove valve spring retainer, valve spring, and valve
stem seal.
(4) Before removing valves, remove any burrs
from valve stem lock grooves to prevent dam-
age to the valve guides. Identify valves to insure
installation in original location.
CLEANING
(1) Clean all
burned, warped and cracked valves.
INSPECTION
VALVES
(1) Clean and inspect valves thoroughly. Replace
burned, warped and cracked valves.
(2) Measure valve stems for wear (Fig. 33). For
valve specifications, (Refer to 9 - ENGINE - SPECI-
the
FICATIONS).
NOTE: Valve stems are chrome plated and should
not be polished (Fig. 33).
Valve Spring Compressor
release valve spring
valves thoroughly
RS
Tool
compressor.
and discard