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TM5-4210-229-14&P
6-13. FLYWHEEL, CRANKSHAFT, AND MAIN BEARING MAINTENANCE (Continued).
(1) Lift the crankshaft out of the crankcase
with a hoist and sling.
(2) Remove the upper main bearing halves.
(3) Remove the rear oil seal wear sleeve using a
muffler chisel. Hold chisel flat against the
crankshaft to prevent damage by the
chisel's point.
INSPECTION
a. Crankshaft and main bearings inspection.
Cleaning solvent, (Appendix D, Item 54), is
both toxic and flammable. Keep off skin. Use
only in a well ventilated area and avoid pro-
longed breathing of vapors. Keep away from
open flames.
(1) Clean all parts with cleaning solvent (Ap-
pendix D, Item 54).
Compressed air used for cleaning or drying
can create airborne particles that may enter
the eyes. Pressure shall not exceed 30 psi
(206 kPa). Wearing of goggles is required to
avoid injury to personnel.
(2) Dry with compressed air.
(3) Clean all the crankshaft internal oil pass-
ages of any dirt or sludge that may have
accumulated. Run a wire brush (Appendix
D, Item 8) through the oil passages to
loosen the deposits, then wash the passages
and external surfaces of the crankshaft
thoroughly with oil (Appendix D, Item 37).
Blow the passages and external surfaces
dry with compressed air.
(4) Visually inspect the bearings for wear and
evidence of uneven bearing support. If such
evidence is found, examine the bearing caps
and supporting surfaces of the crankcase
for high spots and burrs.
(5) Visually inspect the crankshaft journals for
scoring.
(6) Measure the diameter of each journal using
a micrometer. Measure each journal at two
points, at right angles to each other. Move
the micrometer over the entire width of the
journal. Limits of 3.3742 to 3.3755 in
(85.705 to 85.738 mm) must be observed.
(7) Check hardness on every journal which in-
curred a bearing failure or shown evidence
of overheating.
(a) Using a Rockwell Hardness Tester,
check at least three locations.
NOTE
Fillet hardened shafts should be checked as
close to the fillet as possible. Non-fillet har-
dened shafts should be checked at least 1/2
inch (1 3 mm) from the fillet.
(b) Check rod journals at top, bottom and
one other location. (Top and bottom
determined with journal at top dead
center).
(c) Minimum hardness: 45 RC. If any read-
ing is below the minimum hardness,
replace the crankshaft.
(8) Inspect the crankshaft gear teeth and
splined collar for wear and chipping. Re-
place damaged parts as required.
(9) Visually inspect the drilled holes in the main
and connecting rod journals to assure that
all passages are open after cleaning.
6-37
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