TM 5-6115-400-35
(6) Remove the crankshaft.
(d) After all bearing shells have been
installed, retighten main bearing
(7) Remove upper main bearing shells from
capscrews using a torque indicating
the cylinder block.
wrench.
Tighten the capscrews
Note.
evenly to the specified torque (refer
Identify the bearing shells as to their
to para 60).
location in the connecting rods and
Caution.
in the block and main bearing caps
Do not overtighten main bearing
in the event inspection proves they
capscrews. If these capscrews are
can be used again.
overtorqued, bearing caps will be
c. Cleaning and Inspection.
distorted, causing bearing to be
(1) Clean crankshaft thoroughly and inspect
drawn tight against the crankshaft
the journals for scoring, chipping,
journals and premature failure will
cracking, or signs of overheating.
If
result. The crankshaft should turn
crankshaft has been overheated (usually
freely after all capscrews are
indicated by discolored or blue bearing
tightened to the specified torque.
journal surfaces), or is scored or
(e) Check crankshaft end play (refer to
excessively torn, reconditioning or
replacement will be required. Examine
60. Crankshaft and Crankshaft Gear
bearing journals for cracks if over-heating
has occurred.
a. General.
(2) Measure the crankshaft main bearing and
(1) The seven bearing, counterbalanced
connecting rod journals at several places
crankshaft is a steel drop forging,
on their diameter to check for roundness.
carefully heat-tested to assure strength.
The specified diameter of main bearing
The crankshaft is balanced dynamically.
journals is 3.995 inches-3.996 inches;
End thrust of the crankshaft is taken up by
connecting rod journals 3.3725 inches-
thrust flanges at the center main bearing.
3.3735 inches. The only recommended
The specified end play of the crankshaft is
method of reconditioning the crankshaft is
.007 inch-.015 inch and must not exceed
regrinding, as required to accommodate
.023 inch. Thrust flanges are available in
undersize bearings. Chrome plating or
standard size and .005 inch, .010 inch,
metallizing the bearing journals is not
and .015 inch oversize.
recommended.
(2) The crankshaft gear is keyed and pressed
Caution.
onto the front end of the crankshaft with a
When regrinding a crankshaft in the
.0005 inch-.0025 inch interference fit.
field it is important that the original
b. Crankshaft Removal.
journal fillet radii be maintained and
(1) Remove flywheel and flywheel housing.
not decreased.
Decreasing these
Refer to paragraphs 53 and 54.
fillet radii will weaken the crankshaft
(2) Remove the timing gear housing cover.
to the extent that breakage can be
Refer to paragraph 48.
expected.
(3) Remove oil pan, pump, and associated
(3) All main and connecting rod bearing
tubing. Refer to paragraph 51.
journal surfaces of the crankshaft are
(4) Remove connecting rod bearing caps and
hardened to a minimum depth of
shells. Refer to paragraph 57.
approximately .060 inch. Main bearing
(5) Remove main bearing caps and lower
shells .010 inch, .020 inch, .080 inch, and
main bearing shells.
.040 inch undersize are available.
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