TM 9-2320-363-20-1
ENGINE
The M915 family of vehicles are equipped with the Series 60 Detroit Diesel electronically controlled engine. This
engine is a high-speed, 4-stroke-cycle, diesel engine.
The engine uses an in-line cast iron block and has a cast iron cylinder head that contains a single overhead
camshaft, which actuates all the valves (two intake, two exhaust per cylinder) and operates the fuel injectors. The
vertically alined gear train, located at the front end of the engine in a gear case, contains drive gears for the lubricating oil
pump, crankshaft, camshaft, air compressor drive, fuel pump drive, water pump, and alternator drive.
Each engine is equipped with dual full-flow oil filters, a bypass oil filter, an oil cooler, two fuel oil filters,
turbocharger, starting motor, and electronic engine control system.
Full-pressure lubrication is supplied to all main, connecting, and camshaft bearings and to other moving parts. A
gear-type pump draws oil from the oil pan through a screen and delivers it to the oil filters. From the filter, a small portion
of the oil is delivered directly to the turbocharger by an external oil line. The remainder of the oil flows to the oil cooler and
then enters a longitudinal oil gallery in the cylinder block where the supply divides. Part of the oil goes to the cylinder
head, where it feeds the camshaft bearings and rocker assemblies; the remainder of the oil goes to the main bearings and
connecting rod bearings via the drilled oil passages in the crankshaft. Drilled passages in the connecting rod feed oil to
the piston pin and the inner surface of the piston crown.
Air is supplied by the turbocharger to the intake manifold and into the engine cylinders after passing through an
air-to-air intercooler mounted ahead of the cooling system radiator. The intercooler cools the pressurized intake air
charge coming from the turbocharger before it enters the intake manifold.
Engine starting is provided by an electric starting motor energized by a storage battery. A battery-charging
alternator, with a voltage regulator, serves to keep the battery charged.
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