ARMY TM 9-2815-259-24
AIR FORCE TO 38G1-125-2
MARINE CORPS 09249A/09246A-24
c. Intake and Exhaust Valves. Intake and exhaust valves are operated by cam followers, push rods, and rocker arm
assembly. Valve seat inserts in cylinder head are used for intake and exhaust valves.
d. Crankshaft. The crankshaft is a one-piece, heat treated, steel forging which operates in replaceable two-piece main
bearings. The rear thrust bearing has a flange on each side to support crankshaft thrust and to limit end play.
e. Cylinder Liners and Pistons. Cylinder liners are "wet" (surrounded by coolant) and are individually replaceable.
O-rings are used to seal the connection between cylinder block and liners. Pistons are made of cast high-grade
aluminum alloy with internal ribbing. The skirt is cam ground to allow for expansion when heated during operation.
The piston crown has a cut-out swivel cup with a truncated cone in the center. Two compression rings and one oil
control ring are used. The top compression ring is a keystone type ring. All piston rings are located above the piston
pin. The hardened piston pins are fully-floating and held in position by means of retainer rings. Spray jets (piston
cooling orifices) in cylinder block direct pressurized oil to lubricate piston pins and cool pistons. Connecting rods are
forged steel and have replaceable bushing and bearing inserts.
f. Cooling System. The cooling system consists of a radiator, water pump, cooling fan, thermostat, and connecting
hoses. The fan and water pump are both belt driven from the crankshaft pulley. The thermostats control engine
temperature and are installed in top of engine. The function of the cooling system is to maintain a specific operating
temperature of 180 to 220°F (82 to 104°C) for the engine.
g. Lubrication System. The lubrication system consists of oil pan (sump), a gear type pump, full flow spin-on
oil filter with built-in bypass valve, oil cooler with built-in bypass valve, pressure regulating valve, bypass valve,
and the internal passages.
h. Fuel System. The function of the fuel system is to inject a metered quantity of clean atomized fuel into the
engine cylinders at a precise time near the end of the compression stroke of each piston. The fuel system consists
of the fuel tank, fuel filter/water separator, fuel supply pump, fuel injection pump, and the fuel injectors. The
fuel tank is not mounted on the engine. The fuel supply pump is mounted to the block and is driven by the
camshaft. The fuel injection pump is mounted on the front plate and is driven by an intermediate gear in the
timing gear train meshing with crankshaft gear.
i. Electrical System. The electrical system is 28VDC operation and consists of a battery charging alternator,
starter, externally mounted batteries, and other items as required. The battery charging alternator is mounted on
front of engine and is belt driven. When engine is operating, the battery charging alternator supplies 28VDC to
recharge the batteries and maintain them at a full state of charge. The starter is mounted on the flywheel housing,
and when energized, engages the ring gear of the flywheel to rotate the engine.