Jeep Cherokee 2000 Service Manual - page 1138
Use compressed air to blow out the oil passages in
the rocker arms and push rods.
INSPECTION
Inspect the pivot surface area of each rocker arm.
Replace any that are scuffed, pitted, cracked or
excessively worn.
Inspect the valve stem tip contact surface of each
rocker arm and replace any rocker arm that is deeply
pitted.
Inspect each push rod end for excessive wear and
replace as required. If any push rod is excessively
worn because of lack of oil, replace it and inspect the
corresponding hydraulic tappet for excessive wear.
Inspect the push rods for straightness by rolling
them on a flat surface or by shining a light between
the push rod and the flat surface.
A wear pattern along the length of the push rod is
not normal. Inspect the engine cylinder head for
obstruction if this condition exists.
PISTONS AND CONNECTING ROD ASSEMBLY
INSPECTION—PISTONS
(1) Piston Diameter: Size: 91.93-91.94mm (3.6191-
3.6196 in.) Maximum wear limit.05mm (.0019 in.).
(2) Check piston pin bores in piston for roundness.
Make 3 checks at 120° intervals. Maximum out of
roundness.05mm (.0019in.).
(3) The
piston
diameter
should
be
measured
approximately 15 mm (.590 in.) up from the base.
(4) Skirt wear should not exceed 0.1 mm (.00039
in.).
(5) The clearance between the cylinder liner and
piston should not exceed 0.25 mm (.0009 in.).
(6) Make sure the weight of the pistons does not
differ by more than 5 g.
INSPECTION—CONNECTING ROD
(1) Assemble bearing shells and bearing caps to
their respective connecting rods ensuring that the
serrations on the cap and reference marks are
aligned.
(2) Tighten bearing cap bolts to 29N·m (21 ft. lbs.)
plus 60°.
(3) Check and record internal diameter of crank
end of connecting rod.
NOTE: When changing connecting rods, all four
must have the same weight and be stamped with
the same number. Replacement connecting rods
will only be supplied in sets of four.
Connecting rods are supplied in sets of four since
they all must be of the same weight category. Max
allowable weight difference is 18 gr.
NOTE: On one side of the big end of the con-rod
there is a two-digit number which refers to the
weight category. On the other side of the big end
there is a four digit number on both the rod and the
cap. These numbers must both face the camshaft
as well as the recess on the piston crown (Fig. 75).
Lightly heat the piston in oven. Insert piston pin in
position and secure it with provided snap rings.
The Four digit numbers marked on con rod
big end and rod cap must be on the same side
as the camshaft (Fig. 75). After having coated
threads with Molyguard, tighten con rod bolts to 29
N·m (21 ft. lbs.) plus 60°.
INSPECTION—PISTON PIN
(1) Measure the diameter of piston pin in the cen-
ter and both ends.
(2) Piston pin diameter is 29.990 to 29.996mm
(1.1807 to 1.1809 in.).
Fig. 73 Rocker Arm Components
1 – ROCKER ARM
2 – SPRING PLATE
3 – ROCKER SUPPORT
4 – PUSH ROD
5 – HYDRAULIC TAPPET
6 – CAMSHAFT
7 – ANTIROTATION BRACKET
9 - 44
ENGINE
XJ
CLEANING AND INSPECTION (Continued)