TM 9-2330-356-14
b.
Inspection and Repair.
c.
Assembly (Fig. 7-26).
(1) Pistons. Thoroughly clean and inspect each
NOTE
piston. Clean carbon from ring grooves and ensure that all
The piston witness mark (notch) must face
oil holes are open. If any piston is badly scored or buffed,
front of engine and rod witness marks (num-
loose in cylinders, has badly worn ring grooves, or
bers) must face toward camshaft side of en-
otherwise is not in good condition, replace it. Check the
gine.
piston clearance in cylinder 90 from axis of piston pin and
below oil control fig (4, fig. 7-26). Clearance should be
(1) Install connecting rods (12, fig. 7-26) on each
0.0055- to 0.0075-inch. If not, replace piston and check
piston (7) with pins (6) and retaining rings (5). If new
cylinder wall for possible reconditioning.
bushings (13) were installed, check to see that ends are
flush with the connecting rod (12) to provide for oil
passage in center (fig. 7-58).
NOTE
Piston and pins are matched sets and are not
procured separately.
(2) Piston Pins. Each piston pin should be a thumb
push fit into its piston at room temperatures. If pin is
excessively loose, install a new piston and pin assembly.
(3) Rings. Place each piston ring into its cylinder
bore and using a feeler gage, measure gap where indicated
in figure 7-59. Gap is shown in table 7-2. If gap is under
0.010-inch, file as follows:
(a) Place file in vise.
(b) Grasp piston ring in both hands.
(c) Insert file into ring gap and move ring
down the entire length of file. Be sure to apply equal
pressure on the ring.
(4) Connecting Rods (Fig. 7-58). Clean connect-
ing reds and check each for defects. Check connecting rod
(2) Refer to figure 7-59 and install rings and oil
ring expander (1,2,3, and 4, fig. 7-26) on each piston (7).
bushings for proper clearance with piston pin. Clearance
Compression rings will be marked TOP or identified in
some other manner. Place this mark toward the closed end
sively worn, press them out and install one new bushing
of piston. Space ring gaps 1/4 of the way around piston from
from each side of bushing bore. Press new bushings only
one another. No gap should be in line with piston pin. Oil
until flush with sides of rod to leave 1/16-7/64-inch oil groove
the rings (1,2, and 4) and pistons (7).
in center. Ream bushing I.D. to obtain the proper clear-
ante. Check bore in connecting rod. Bore must be open.
NOTE
Check connecting rod alinement on a standard alinement
fixture.
Ensure that rod bearings are Installed In the
same position they were In before they were
removed.
(5) Connecting Rod Bearings (Fig. 7-26). Inspect
connecting rod bearings for burrs, breaks, pits, and wear.
Measure clearance between bearings and crankshaft
(3) Position a bearing half (11) in connecting rod
journal (table 7-2). If necessary, replace with new standard
(12) and cap (10). Be sure there is no dirt under bearing.
This could cause high spots and early bearing failure.
or under size precision bearings.
7-52
