d. Use a depth micrometer or dial indicator to
i. Remove cotter pin (42) and carefully push
measure piston-head-to-valve-seat clearance. Required
piston pin (41) out of the piston assembly (40). Use
clearance is 0.002 to 0.006 inch. If necessary, remove
care to prevent loss of the 25 needle bearings (44) and
cylinder and add or remove cylinder-to-crankcase
two washers (43) which will drop out of the piston
gaskets to obtain required clearance.
assembly when the piston pin is removed. Scribe a
small mark on the inside of the piston skirt toward the
Note
fan end of the crankcase for correct reassembly.
j.
Do not disassemble the piston assembly.
Overall thickness of steel gaskets can
be reduced in increments of 0.002 inch
2-53.
CLEANING AND INSPECTION.
by peeling off laminations. At least one
paper gasket must remain on each side
of steel gasket in final installation.
a. Clean all parts with dry cleaning solvent,
Federal Specification P-D-680.
e. Install rupture disc (32) into cylinder cap (33),
with the red side of the disc toward the retainer end of
b. Inspect all parts for obvious indication of
the cap. If applicable, place disc retainer ring (50),
damage such as damaged screw threads, scratched,
chamfered edge toward the rupture disc, into the
pitted, or worn finished surfaces, and broken cooling
cylinder cap. Install disc retainer (29 or 31) and tighten
fins.
to 60 to 90 inch-pounds torque.
c. Inspect the cylinder bore, piston assembly,
f.
Install exhaust valve (35) and valve spring (34).
piston pin, connecting link and bearing for excessive
wear, scoring, and other damage.
g. Screw the cylinder cap into the cylinder and
tighten to 300 inch-pounds torque.
d. Refer to table 2-1 for wear tolerances.
2-54.
REASSEMBLY.
h. Apply lubricating oil FSS 9150 53-4667 to the
threads of relief valve (23), back-up ring (25), and
gasket (26). Install the relief valve.
a. Place 25 needle bearings (44) around the inside
diameter of the piston pin hole in the connecting link.
i.
Install reducer bushing (27) and seal (28).
Place one washer (45) over each end of the bearings.
Carefully slide piston assembly (40), with the mark
j.
Install the fan assembly (paragraph 2-38).
scribed in disassembly toward the fan end of the
crankcase, over the connecting link and press piston pin
k. Connect the intercooler assemblies (paragraph
(41) through the piston, washers, bearings, and
connecting link. Secure the piston pin with cotter pin
(42).
2-55.
CRANKCASE.
Note
2-56.
Assembly of the needle bearings and
a. Remove the aftercooler assembly (paragraph
washers into the connecting link can be
facilitated by applying a coat of
Petrolatum, VV-P-236.
b. Remove the fan assembly (paragraph 2-36).
b. Place gasket (39) between two gaskets (38) and
c.
Remove the intercooler assembly (paragraph 2-
position the gaskets onto the crankcase mounting
40).
flange.
d. Open drain cock (4) and allow all oil to drain
c. Carefully slide cylinder (36) over the piston
from oil reservoir (1). Remove dip stick plug (8) to
assembly and attach to the crankcase with nuts (37).
facilitate drainage.
Tighten the nuts with equal torque.
2-12
