ARMY TM 9-2815-255-24
AIR FORCE TO 38G1-95-2
MARINE CORPS TM 2815-24/4
Section I. PRINCIPLES OF OPERATION
This section contains functional descriptions of the engine systems and how they are connected to the end item.
2-2. COOLING SYSTEM.
The cooling system consists of a radiator, hoses, thermostat, belt driven fan, water pump, and cooling jackets within the
engine. The water pump forces coolant through passages (coolant jackets) in the engine block and oil cooler where
coolant absorbs heat from the engine. When the coolant temperature is below operating temperature, the thermostat is
closed and coolant is bypassed to the water pump inlet. As coolant temperature increases to 180°F (82°C), the
thermostat fully opens, shutting off all bypass flow and providing full flow through the radiator. Air forced through the fins
of the radiator by the fan cools the coolant pumped through the radiator. Items are added to the engine to monitor
coolant temperature and to warn if temperature exceeds a predetermined value.
2-3. LUBRICATION SYSTEM.
The pressure lubrication system consists of a positive displacement gear-driven pump, filter strainer in the suction pipe,
full flow oil filter, oil cooler, oil pressure regulating valve, and oil by-pass valve. Additionally, the oil cooler and oil filter
have their own bypass valve. The pump draws lubrication oil from the crankcase through a strainer and a suction line.
The oil is then pumped through an oil line to the oil cooler, oil filter, and through the main oil gallery of the cylinder block.
From the oil gallery, oil is forwarded under pressure to the main bearings and spray jets to cool the pistons. Drilled cross-
passages in the crankshaft distribute oil from the main bearings to connecting rod bearings. Lube oil holes in Nos. 1, 3,
and 5 main bearing oil grooves are provided to direct oil to the camshaft bearings. A drilled passage from the rear
camshaft bearing through the cylinder block and cylinder head supplies lubricating oil to the rocker arm shaft. An oil
passage direct from the main oil gallery provides lubricating oil to the shaft of the turbocharger. Items are added to
monitor oil pressure and to warn/stop engine if pressure drops to a dangerously low value.
2-4. FUEL SYSTEM.
The fuel system consists of an external fuel tank, fuel supply pump, fuel filter/water separator, fuel injection pump, fuel
injectors, and piping. The fuel supply pump draws fuel from the tank and pressurizes it. This pressure permits the fuel to
flow through the fuel filter/water separator and charge the transfer pump of the fuel injection pump. With the fuel
injection pump charged with fuel by the fuel supply pump, the fuel injection pump plungers pressurize the fuel to
approximately 7255 psi (50,000 kPa). Delivery (pressure) lines are used to route this high pressure fuel to the fuel
injection nozzles. Fuel enters the injection nozzle at a pressure which easily overcomes the pressure required to open
the nozzle valve. When the nozzle valve opens, fuel is forced out through the orifices in the nozzle tip and atomizes as
it enters the combustion chamber. The fuel that is not used by the injectors and injection pump is returned to the fuel
tank via an excess fuel return line.
2-5. ELECTRICAL SYSTEM.
The electrical system consists of external mounted batteries, starter, battery charging alternator, and related relays and
switches for control of the system. Battery power supplied to the starter during the start cycle energizes the starter which
engages the ring gear of the flywheel causing the engine to turn over. When engine start is complete the starter is
deenergized and disengages from the flywheel. The battery charging alternator is belt driven. It is a 42 ampere, 24 VDC
alternator that when operating supplies voltage to recharge the batteries and maintain them at a full state of charge.
Section II. OPERATING INSTRUCTIONS
Refer to end item operator's manual.