Jeep Cherokee 2000 Service Manual - page 1106
INSPECTION
(1) Inspect for cracks in the combustion chambers
and valve ports.
(2) Inspect for cracks on the exhaust seat.
(3) Inspect for cracks in the gasket surface at each
coolant passage.
(4) Inspect valves for burned, cracked or warped
heads.
(5) Inspect for scuffed or bent valve stems.
(6) Replace valves displaying any damage.
(7) Check valve spring height (Fig. 2).
VALVE REFACING
(1) Use a valve refacing machine to reface the
intake and exhaust valves to the specified angle.
(2) After refacing, a margin of at least 4.52-4.49
mm (.178-.177 inch) must remain (Fig. 3). If the mar-
gin is less than 4.49 mm (.177 inch), the valve must
be replaced.
VALVE SEAT REFACING
(1) Install a pilot of the correct size in the valve
guide bore. Reface the valve seat to the specified
angle with a good dressing stone. Remove only
enough metal to provide a smooth finish.
(2) Use tapered stones to obtain the specified seat
width when required.
VALVE STAND DOWN
Valve stand down is to maintain the adequate com-
pression ratio.
(1) Invert cylinder head.
(2) Fit each valve to its respective valve guide.
(3) Using a straight edge and feeler gauge (Fig. 4),
check valve head stand down: Inlet valve head stand
down 1.08 to 1.34 mm (.042 to.052 ins.) and exhaust
valve stand down.99 to 1.25 mm (.035 to.049
(3) ins.).
(4) If valve hea d stand down is not in accordance
with above, discard original valves, check stand down
Fig. 2 Valve Spring Chart
LOAD Kg
HEIGHT mm
STATE
P1
0.00
H1
44.65
FREE LENGTH
P2
32-36
H2
38.60
VALVE CLOSED
P3
89-96
H3
28.20
VALVE OPEN
Fig. 3 Valve Specification
MEASUREMENT
INTAKE
EXHAUST
A
7.940-7.960
7.922-7.940
B
8.00-8.015
8.000-8.015
C
1.08-1.34
0.990-1.250
D
2.2
6
0.08
2.09-+0.07 −0.09
E
1.80-2.20
1.65-2.05
F
2.73-3.44
2.45-3.02
G
41.962-41.985
35.964-35.987
H
42.070-42.086
36.050-36.066
I
7.14-7.19
7.00-7.05
L
3.11-3.26
3.10-3.25
9 - 12
ENGINE
XJ
SERVICE PROCEDURES (Continued)