TM 5-4310-354-14
4. When regrinding crankshafts, all
NOTE
journal fillets must have a 0.140
to 0.170-inch (3.556 to 4.318
The upper main bearings (8, 9) can be
mm) radius between the crank
installed with the crankshaft (12) in
cheek and the crank journal,
place. Install a small tee-shaped pin
and must not have any sharp
into the crankshaft oil hole. After
grind marks. The fillet must
starting the bearing into place, rotate
blend smoothly into the journal
the crankshaft to seat it on the
and cheek, and must be free of
cylinder block, as shown in figure
scratches.
5. After all of the regrinding
(3) Apply clean engine oil to all of the
operations
have
been
crankshaft journals and bearings
completed, perform another
and, using a sling and hoist,
magnetic particle inspection of
carefully set the crankshaft in place
the crankshaft to determine
so that the timing marks on the
whether grinding cracks have
crankshaft gear and the camshaft
originated
due
either
to
gear align as shown in figure 7-50.
insufficient cooling or crowding
of the grinding wheel. Finally,
(4) With the lower main bearings (7, 8,
demagnetize the crankshaft.
caps (3, 4, 5, 6) from which they
6. Wash and clean the crankshaft
were removed, install the caps in
with diesel fuel and blow dry
their original positions on the
with air.
Blow out the oil
cylinder block.
The caps are
passages to make sure they are
marked with the cylinder number in
clear.
which they are used. The center
main bearing cap (6) is secured with
c. Reassembly and Installation.
four -inch (12.7 mm) diameter
bolts (2). The remaining bearing
(1) Install the crankshaft gear (10, figure 7-60)
caps (3, 4, 5) are secured with two
onto the crankshaft. Use an arbor press,
9
/16-inch (14.2875 mm) diameter
if available, to press the gear on the shaft.
bolts (1) each. Draw the bolts up
Make sure the woodruff key (11) is in
snug, then rap the caps sharply with
place. If an arbor press is not available,
a soft hammer to seat them
the following method may be used:
properly. Check the original center
main bearing cap (6) for a T
(a) Insert the woodruff key (11) in the
stamped on the side opposite the
crankshaft (12) keyway.
cylinder number to determine the
required torque value. Tighten the
(b) Lay the gear (10) on a sheet of
bearing cap bolts (1, 2) to the torque
asbestos or other fireproof material
specified in table 1-1. Start with the
and, with a torch, heat the gear
center cap and work alternately
evenly on both sides until the gear
toward both ends of the block. If the
turns a pale straw yellow. (If the
bearings
have
been
installed
gear is clean and untarnished, this
properly, the crankshaft will turn
color will indicate it is heated to
freely with all main bearing caps
approximately 45 F (232 C).
drawn down to the specified torque.
(c) Assemble the hot gear (10) on the
(5) After installing crankshaft with new
crankshaft (12) and quickly drive the
bearings and center thrust bearing,
gear into the correct position. A
check the crankshaft end thrust.
piece of 2-inch (50.8 mm) diameter
Insert different dimension feeler
pipe may be used as a driver.
gauges until one just fits between
the center thrust bearing and the
(d) Allow the gear and shaft to cool.
crankshaft as shown in figure 7-62.
This dimension must be between
0.005 and 0.010 inch (0.127 and
(2) Install the upper main bearings (8, 9) in
0.254 mm) for new bearings, and
the cylinder block. The upper bearings
the maximum allowable clearance of
are the bearings with two holes and an oil
0.015 inch (0.381 mm). Insufficient
groove. The bearings must be installed in
clear
the same positions from which they were
removed.
7-68
