TM 5-3810-206-35
Remove key (11) and shaft (12) from housing (7).
No. 1 piston is at top center on the compression stroke.
(5) Reassemble by reversing procedure in steps
(2) The timing marks on gears should be
(1) through (4) above.
matched as follows:
c. Cleaning, Inspection, and Repair.
(a) The C on crankshaft drive gear must
(1) Clean all parts and dry thoroughly before
coincide with the C on camshaft gear.
inspection or reassembly.
(b) The F on camshaft gear must coincide
(2) Inspect shaft for straightness or wear.
with the F on accessory drive idler gear.
Inspect seals for wear or deterioration. Inspect gear for
(c) The AB on accessory drive gear must
chipped or broken teeth, or excessive wear. Inspect
coincide with the B on accessory drive idler gear.
mounting hardware for burs or stripped threads.
(3) If the timing marks are not properly aligned,
(3) Repair by replacing defective components.
they must be removed from their shafts and repositioned
until the marks do coincide as described in (2) above.
3-33.
Accessory Drive (Engine Model D333TA)
3-32.
Injection Pump Drive (Engine Model 687C-18-
a. Removal and Installation.
ES)
(1) Remove fuel transfer pump (para 3-18).
(2) Remove fuel filter (TM 5-3810-206-12).
a. Removal and Installation.
(3) Disconnect governor control linkage, then
(1) Remove fuel injection pump (para 3-17).
remove fuel injection pumphousing and governor as a
(2) Remove flywheel housing (para 3-40).
unit
(3) Remove left hand threaded nut (7, fig. 3-39),
(4) Remove front cover (pa ra 3-31).
then remove oil line from drive mechanism.
(5) Remove accessory drive gear, then remove
(4) Use a puller and loosen fuel injection pump
four bolts and locks that secure adapter housing to
drive gear (3) on shaft.
timing gear plate, and remove adapter housing.
(5) Remove gear from shaft then remove drive
(6) Install by reversing procedure in steps (1)
mechanism from flywheel housing.
through (5) above. Align timing marks.
(6) Install by reversing the procedures in steps
(1) through (5) above. Align timing marks.
b. Disassembly and Reassembly.
in reverse order.
(1) Remove three nuts (3, fig. 3-20) washers (4)
c. Cleaning, Inspection, and Repair.
Clean,
and studs (5) from backplate.
inspect, and repair in a manner similar to that described
(2) Remove gasket (6) from housing (7).
in paragraph 3-32c above.
(3) Remove two seals (16), retaining ring (14),
seal (15), and ring (13) from shaft (12).
(4) Remove three studs (10) from housing (7).
Section X. VALVE OPERATING MECHANISM
excessive carbon deposits is minimized, and promotes
3-34. General
longer valve life.
a. Engine Model 687C-18-ES. This engine is a
two-stroke cycle type with exhaust valves only, which
3-35.
Valve Operating Mechanism
for
Engine
are operated by lobes on a camshaft located in right side
Model 687C-18-ES
of crankcase. Cam follower rollers actuate pushrods
a. Removal and Installation.
which operates the rocker arm located on cylinder head.
(1) Remove valve cover and gasket (TM 5-
Movement of rocker arm opens exhaust valve during
3810-206-12).
exhaust stroke of the piston.
(2) Loosen locknut (7, fig. 3-42) and turn
b. Engine Model D333TA. This engine is a four-
adjusting screw (8) counterclockwise until rocker arm
stroke cycle type with exhaust and intake valves. In
(16) is without pressure on valve spring (13).
general, their operation is similar to other engines. With
(3) Remove two selflocking screws (6) securing
addition of valve rotators that cause valves to turn a
supports (5) to cylinder head (4).
minute distance with each operation, the formation of
3-51
