Pistonslconnecting Rods-Removal - Jeep cherokee 1989 Owner's Manual

2D-12
shown here before installation
on the valve stem as the spring is released
11.9 Be sure t o check the valve spring installed height
(the distance from the top of the seatlshims t o the top of
the shield or the bottom of the retainer)
12.1
A ridge reamer is required t o remove the ridge from
the top of each cylinder
removing the pistons!
The Motor Manual Guy
2 Part D
Chapter General engine overhaul procedures
it will hold them i n place
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do this before
A special adapter and vacuum pump are required t o
11.8
check the O-ring valve stem seals for leaks
then slowly release the compressor and make sure the keepers seat
properly. Apply a small dab of grease to each keeper to hold
if necessary (see illustration).
7
Repeat the procedure for the remaining valves. Be sure to return
the components to their original locations
8 On V 6 engines, when all the valves are in place in both heads, the
valve stem O-ring seals must be checked to make sure they don't leak.
This procedure requires a vacuum pump and special adapter (tool no.
department, repair shop or automotive machine shop. The adapter is
positioned on each valve retainer or rotator and vacuum is applied with
the hand pump (see illustration). If the vacuum can't be maintained,
the seal is leaking and must be checkedtreplaced before the head is
installed on the engine.
9 Check the installed valve spring height with a ruler graduated in
1132-inch increments or a dial caliper. If the head was sent out for ser-
vice work, the installed height should be correct (but don't automatically
assume that it is). The measurement is taken from the top of each spring
seat or shim(s) to the top of the oil shield (or the bottom of the retainer1
rotator, the t w o points are the same) (see illustration). If the height
is greater than specified, shims can be added under the springs to cor-
rect it. Caution: Don't, under any circumstances, shim the springs to
the point where the installed height is less than specified.
then install the rocker arms and pivots on the cylinder head. Thread
the boltstnuts on three or four turns only (when the heads are installed
on a V 6 engine, the nuts will be tightened following a specific pro-
cedure).
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12 Pistonslconnecting rods
Refer to illustrations 12.1, 12.3 and 12.6
Note: Prior to removing the piston/connecting rod assemblies, remove
the cylinder headlsl, the oil pan and the oil pump by referring to the
appropriate Sections in Chapter
1 Use your fingernail to feel if a ridge has formed at the upper limit
of ring travel (about 114-inch down from the top of each cylinder). If
carbon deposits or cylinder wear have produced ridges, they must be
completely removed with a special tool (see illustration). Follow the
manufacturer's instructions provided with the tool. Failure to remove
the ridges before attempting to remove the pistontconnecting rod
assemblies may result in piston breakage.
2 After the cylinder ridges have been removed, turn the engine up-
side-down so the crankshaft is facing up.
3 Before the connecting rods are removed, check the end play with
feeler gauges. Slide them between the first connecting rod and the
crankshaft throw until the play is removed (see illustration). The end
play is equal to the thickness of the feeler gauge(s). If the end play
in place
it
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don't mix them up!
removal
2.