TM 5-3810-295-34
(5) Using a large screwdriver inserted into slots of
pletely with compressed air.
intake valve seat, rotate seat (35) from cylinder head
& Remove all carbon from valve cavities and all rust
and dicard.
and scale from water cavities. Remove dirt from all
(6) Remove intake valve (36) and spring (37) from
cavaties using compressed air.
head (43); discard spring.
CAUTION
(7) Remove capscrews (38) lock washers (39), and
Do not use a screwdriver to remove carbon
washers (40). Lift cover (41), gasket (42), head (43), and
and scale; this may damage the sealing sur-
gasket (44) from crankcase (69); discard gaskets.
faces.
(8) Press exhaust valve assembly from under side
c Remove or drill out oil restrictive orifice.
of head with thumb pressure. Remove preformed pack-
13-29. Inspection and Repair
ing (45), from exhaust seat (47).
a. Check visually for cracks, breaks or excessive
(9) Remove exhaust valve (46) from exhaust seat
scoring in the cylinder head.
(47). Remove and discard preformed packing (48).
& Check exhaust valve seat height. If height is less
Remove wear plate (49) and spring (50) from head (43).
than 0.485 inch, discard seat.
(10) Using a suitable gear puller, remove drive
c Check intake valve seat height. If height is less
gear (51). Remove key (52).
than 0.270 inch, discard seat.
(11) Remove capscrews (53) and (54), washers
d. Apply "bluing" to exhaust and intake valve seat-
(5), and lock plates (56). Remove suppot (57) and
ing surfaces to check seats. Seating surfaces that are
gaskets (58) and (59). Discard gaskets.
not 100% true may be lapped. Discard valve assembly if
CAUTION
lapping will reduce seat height beyond the described
Do not damage rod bearing (68) when remov-
wear limits.
ing crankshaft (60).
e. If lapping is required for a good seat, follow the
(12) Remove crankshaft (60) by rotating while
steps outlined.
pulling from crankcase (69). Remove plug (61).
(1) Apply "bluing" to surface of exhaust valve to
NOTE
be lapped and allow to dry.
Clean carbon from worn ridge at top of
(2) Apply lapping compound to exhaust valve and
crankcase bore.
place valve on seat.
(13) Push piston and rod assembly out top of
(3) Insert valve seat in lapping block and using a
crankcase and remove piston rings (62), (63) and (64)
standard hand lapper and rubber suction cup, lap valve
from piston (65). Discard piston ring (62).
until a good seat is acquired. Valve must be fiat within
NOTE
0.001 inch total indicator reading.
Discard all rings if worn excessively.
(4) Remove all lapping compound.
(14) Remove piston pin retaining rings (66). Place
f If intake valve requires lapping proceed as
piston in hot water to expand piston pin bore.
follows.
CAUTION
(1) Install rubber buffer in top of exhaust valve
Do not drive pin from piston, as this will dis-
seat.
tort piston (65).
(2) Apply "bluing" to intake valve and allow to
(15) Push piston pin (67) from piston (65). Remove
dry.
connecting rod (68).
(3) Apply lapping compound to intake valve.
NOTE
Place valve seat on intake valve and lap until a good
Parts should be placed in a pan or rack to pre-
seat is acquired. Valve must be fiat within 0.001 inch
vent damage.
total indicator reading.
(16) Remove bushing (70) from crankcase (69). If
(4) Remove all lapping compound.
required remove drive screws (71) and name plate (72).
g Check for scoring or excessive wear on upper part
13-28. Cleaning
of unloader cap where packing seal seats. If top of
a. Clean all metal parts with cleaning solvent,
unloader cap sticks beyond bottom of unloader body,
Federal Specification P-D-680, or equivalent. Dry com-
file a cross on top of unloader cap. See figure 13-9.
13-18
