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TM5-4210-229-14&P
6-13. FLYWHEEL, CRANKSHAFT, AND MAIN BEARING MAINTENANCE (Continued).
(b) Install new oil jet tubes with the same
pilot driver.
(c) The jet tube (when installed) must not
project above the surface; but must be
recessed 1/8 inch (3mm) below the sur-
face.
(d) The top half of the main bearing insert
is slotted to provide a flow of oil to the
jet tubes and camshaft bushings.
INSTALLATION
a. Crankcase trueness cheek (prior to installation).
(1) Using a lint-free cloth (Appendix D, Item
14) wipe the bearing supports of the
crankcase free of oil.
(2) Support the crankcase bottom side up using
wooden blocks to level it.
(3) Install the upper halves of the bearings
(bearings with oil hole in center) on the
crankcase.
(a) If the original bearings are to be rein-
stalled, be sure they go to the positions
from which they were removed.
(b) The nibs of the bearings must fit into
the notches in the crankcase bearing
supports.
(4) Apply bluing ink (Appendix D, Item 23) on
the crankshaft main journals and lower them
carefully and evenly onto the bearings. Do
not install the bearing caps and lower bear-
ings.
(5) Rotate the crankshaft approximately 1/2
revolution.
(6) Remove the crankshaft evenly and inspect
the upper bearings for an even transfer of
bluing (Appendix D, Item 23) from journals
to bearings.
(7) Replace any bearings that do not show an
over-all even bluing.
NOTE
Replace all bearings with new, if one of the
original bearings has to be replaced.
(8) When satisfied that the crankcase is in good
order and free from any distortion and
burrs around the upper bearing seats, pro-
ceed with installation.
(a) Clean all bluing from the bearings and
crankshaft journals.
(b) If using the original bearings coat the
bearing surfaces with a small amount of
clean oil (Appendix D, Item 37).
(c) Install the bearing halves (bearing with
oil hole in center).
(d) Carefully install the crankshaft.
b. New main bearing caps installation.
(1) Place a drill rod or a new drill of any size
from 1/4 to 1/2 in (6 to 13 mm) in the bore of
the OLD caps. Measure the distance from
the face of the cap to the drill rod shank with
a depth gauge and record the reading.
(2) Measure the diameter of the drill rod shank
with a micrometer and add this reading to
the one taken with the depth gauge, to de-
rive dimension.
NOTE
If the cap being replaced is broken and dimen-
sion cannot be determined, use one of the
other caps to measure this dimension. Install
and torque the capscrews to 115 ft-lb (155 N.m)
before continuing.
6-39
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