TM 5-3805-255-14
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ENGINE CONTINUED
Rotation (Engine and Injection Pump) . . . . . . . . . . . . . . . . . . . . . . . . Counterclockwise (viewed from flywheel end)
Firing Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5-3-6-2-4
Compression Ratio:
Running . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1:1
Injection Pump Timing - Static (Crankshaft Degrees) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 degrees BTDC
Crankshaft
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The crankshaft is fully counterbalanced with induction-hardened journals.
The crankshaft supports six connecting rods and pistons along its length. At the front end of the crankshaft, a
timing gear-train supplies drive for camshaft, injection pump, lubricating oil and water pump, fan drive housing, and
hydraulic pump. The flywheel is mounted to the rear end of the crankshaft. Two main seals, one at the front and
one at the rear, prevent leakage of engine lubricating oil around the ends of the crankshaft.
Bearing caps are furnished with crankcase and support the crankshaft in true alignment. Webs integral with the
crankcase provide upper half of main bearing supports and removable bearing caps provide lower support. Seven
bearing caps are held in place with two cap screws each. Bearing caps are not interchangeable, and each has a
number stamped upon them which signifies the correct location in the crankcase. The No. 1 bearing cap is at the
front of the engine.
NOTE
Extreme care must be taken to guarantee cleanliness of crankcase, crankshaft, and
bearings after service has been completed. Whenever possible, crankshaft should be
removed when new bearings are being installed in order to clean crankcase thoroughly.
All bearing surfaces must be free of grit and burrs. Small particles of dust and dirt left
between crankshaft and bearings will cause rapid wear and scoring of crankshaft journal
and bearing insert. Any foreign material left between bearings and crankcase and bearing
caps will cause distortion of bearing and reduction in operating bearing clearance at that
point. Frictional heat thus produced, will in turn, cause bearing material to melt away from
steel back of bearing at that point. Such melted material will create further hot spots until
complete bearing failures take place. Anything that interferes with operating clearance of
any bearing or proper heat dissipation will drastically affect bearing life. Cleanliness
cannot be overstressed.
Bearing inserts are of the precision type. The words "UPPER" and "LOWER" are stamped on the back of bearings
for identification purpose. Bearings are inserted between crankshaft and crankcase and between crankshaft and
bearing caps. Rear main bearing is the thrust bearing and has thrust flanges that determine crankshaft end-play.
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