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TM 5-4320-305-24
4-12. REPLACE/REPAIR CRANKSHAFT ASSEMBLY (Continued)
For both of these out-of-round conditions, also check connecting rods, pistons, cylinder, and main bearing bushings
for unusual wear. Journal width measured at point 3 should be 1.4173 to 1.4189 inches (36.0 to 36.039 mm). Fillet
radius measurement should be 0.1693 to 0.1772 inch (4.30 to 4.50 mm). If either measurement is outside specified
limits, the crankshaft must be replaced.
8
Inspect crankshaft center bearing journal.
a.
Measure diameter of crankshaft center bearing
journal (1) at points 1 and 2 and along axes A
and B with micrometer. Measure width of
journal at point 3. Measure radius of fillets (2)
between center bearing journal and crank
cheeks (3).
b.
Nominal center bearing journal diameter should
be 2.8728 to 2.8736 inches (72.97 to 72.99
mm). If any measurement is outside the
specified limits, the crankshaft must be
replaced. However, if journal is evenly worn,
not out-of-round, and main bearing journal and
crankpin diameters are within their specified
limits, only center main bearings need be
replaced.
c.
Replace main bearings in accordance with
paragraph 4-13. Make sure that main bearing
radial clearance does not exceed 0.0020 to
0.0118 inch (0.052 to 0.3 mm). If specified
limits are exceeded, the crankshaft must be
replaced.
d.
If measurements at points 1 and 2 differ by more than 0.0028 inch (0.07 mm) and/or one set is outside the
specified limits, the journal is worn into a conical shape and crankshaft must be replaced. If measurements
along axes A and B differ by more than 0.0028 inch (0.07 mm) and/or one set is outside the specified limits,
the journal is worn into an oval shape and crankshaft must be replaced. For both these out-of-round
conditions, also check connecting rods, pistons, cylinders, main bearing bushes, and main bearings for
unusual wear. Journal width measured at point 3 should be 1.4576 to 1.4577 inches (37.0 to 37.025 mm).
Fillet radius measurement should be 0.1693 to 0.1772 inch (4.30 to 4.50 mm). If either measurement is
outside specified limits, the crankshaft must be replaced.
REPAIR:
1
Inspect crankshaft drive end (to flywheel) contact surface. Lightly stone surface with surfacing stone to remove any
fretting or brinnelling. Remove dirt and debris from contact surface.
WARNING
Death or serious injury could occur if diesel fuel oil is not handled carefully. Use
in a well-ventilated area away from open flame, arcing equipment, ignition
sources, heaters, or excessive heat. Always store fuel in proper, marked
containers. DO NOT SMOKE.
2
If crankpins and bearing journals are only slightly outside specified limits because of nicks, burrs, or high spots,
remove these slight imperfections with crocus cloth wet with diesel fuel oil. Work wet crocus
4-98
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