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 crankshaft appears to be in good condition, it is unnecessary
(6)
Installation.
to remove the crankshaft to change main bearings (see c.
(a) Support the inner face of flywheel
below).
housing on a flat surface.
(b) If used, install the spacer or sleeve.
b. Crankshaft Oil Seals. An oil seal is used at each end
of the crankshaft to retain lubricating oil in the crankcase.
NOTE
(1) Front oil seal removal.
There is a plastic coating on the outside
(a) Remove the crankshaft pulley (d.
diameter of the current oil seal. Do not
below) .
remove this coating. If the seal to be used
(b) Remove the vibration dampener (e
is not pre-coated, apply a non-hardening
below) .
sealant to the periphery of the metal
(c) Remove the front oil seal by using a
casing.
small pry and working it out of the crankshaft front cover. Be
(c) Position the seal with lip pointed toward
very careful and avoid any damage to the crankshaft journal,
the inner face (or shoulder of counterbore) of the housing.
or the oil seat in the cover,
(d) Drive the seal into the housing by
(2) Cleaning, inspection, and repair.
tapping gently with a soft hammer until it is seated in the
(a) Clean the oil seat thoroughly, then
counterbore, against spacer (if used) or on shoulder in the
inspect seat for scoring, or grooves on oil seat surfaces.
housing bore.
Replace a defective oil seal.
(e) Install the flywheel housing (para 5-6).
(b) Inspect crankshaft surface of oil seal
c. Main Bearings.
Main sleeve bearings of the
contact for pitting or burrs. Slight ridges may be removed
replaceable type are used at each journal. They consist of an
with 120 grit emery cloth, followed by 240 grit. Rotate
upper half carried in the crankcase main bearing support, and
crankshaft during this operation, to prevent an out-of-round
a lower half seated in the main bearing cap. The bearing
condition. Use crocus cloth dampened with fuel oil to polish
caps are numbered with their position 1, 2, 3, etc., with
the surface. If this does not perfect the surfaces, replace the
matching numbers stamped on the bottom of the crankcase,
crankshaft.
on blower side. Each bearing cap must be installed in its
(3) Installation. There is a plastic coating on the
same original position, and must register with a milled slot in
outside diameter of new seals. Do not remove this coating.
the cylinder block to prevent side-to-side movement when
If, however the seal is not pre-coated, apply a non-hardening
bolted in-place. If main bearing trouble is suspected, remove
sealant to the periphery of the metal casing. Install as
the oil pan, then remove main bearing caps (one at a time) as
follows:
outlined below and examine the bearing halves.
(a) Apply a light coating of grease to the
NOTE
sealing lip, then position seal in seat with lip pointed toward
All of the main bearing load of the engine
the inner face of front cover (toward engine).
is carried on the lower hearing halves,
(b) Drive seal into seat with a soft face
therefore wear will occur on them first.
hammer, tapping lightly around the circumference in order
Chipping, pitting, scoring. or overheating
that it will be driven in evenly.
of the lower halves may be observed by
(c) Remove all excess sealant from cover
removing bearing caps, one at a time.
and seal.
(1) Removal. When removal of main bearings
(d) Install the crankshaft front cover (f.
becomes necessary, but removal of crankshaft is not required,
below).
proceed as follows:
(e) Install the vibration damper (e. below).
(a) Disconnect the power generator (para
(f) Install the crankshaft pulley (d. below).
(g) Install the generator drive belt, then
(b) Drain lubrication system and cooling
replace the belt guard.
system .
(4) Rear oil seal removal.
(c) Refer to paragraph 5-2 and remove
(a) Remove the flywheel housing (para 5-
accessories as required in order that engine may be hoisted
out of mounting bed and turned up to expose the oil pan.
(b) Support the rear face of housing on
(d) Remove the oil pan (para 5-4b.(6), (7),
wood blocks.
(8), and warning). Remove the oil pump.
(c) Drive the oil seal out of the housing.
NOTE
(5) Cleaning, inspection, and repair.
If there are shims between legs of oil
(a) Clean the oil seat thoroughly, then
pump and hearing caps, tag for
inspect for scoring or grooves in seat.
(b) Inspect surface of crankshaft at point of
identification and save shims for
seal contact for pitting or burrs.
Replace a defective
installation.
crankshaft (g. below)
(e) Remove bolts (6, fig. 5-31) and the
main hearing caps (5) (one at a time).
5-37
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