ARMY TM 9-2815-255-24
AIR FORCE TO 38G1-95-2
MARINE CORPS TM 2815-24/4
NOTE
All locations referenced herein are given facing the flywheel end (rear) of the engine.
1-8. DETAILED DESCRIPTION.
1-8.1. Turbocharger. A turbocharger, operated by exhaust gases, compresses intake air and routes it to the combustion
chamber.
1-8.2. Camshaft. The camshaft is driven by an intermediate gear in the timing gear train which meshes with the
crankshaft gear. Camshaft rotates in honed machined bores in cylinder block; no bushings are used. The camshaft
lobes determine the time and rate of opening of each valve and actuates the fuel supply pump.
1-8.3. 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.
1-8.4. 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.
1-8.5. 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 of forged steel and have
replaceable bushing and bearing inserts.
1-8.6. Balancer Shafts. Two balancer shafts are used to reduce vibration. They are gear driven by the timing gears and
rotate on bushing in cylinder block. They counter-rotate at twice the engine speed.
1-8.7. Cooling System. The cooling system consists of a radiator, water pump, cooling fan, thermostat, and connecting
hoses. The fan is mounted on shaft of water pump and both are 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 175 to 1850F (79 to 850C) for the engine.
1-8.8. 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.
1-8.9. 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.
1-8.10. Electrical System. The electrical system is 24 VDC 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 24 VDC 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.
1-2
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