Quantcast Main Bearings and Crankshaft - TM-5-4320-234-340082

 

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Figure 4-14. Checking piston fit in cylinder bore.
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TM-5-4320-234-34 Pump Centrifugal Self-Priming Gasoline Engine Driven Wheel Mounted 6-Inch 1500 GPM Capacity At 60 Foot Head Manual
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Figure 4-15. Removing upper bearing shell with angular pin.
TM 5-4320-234-34
bearing and journal, and install the bearing cap. Tighten
ring exceeds 0.017 inch (0.0425 cm), the cylinder is
the connecting rod cap bolts to 40 to 45 footpounds
worn oversize and the cylinder block must be replaced.
(5.532 to 6.223 kgm) torque. Rotate the crankshaft to
(6) Install the oil ring in the bottom ring
determine the amount of drag.  If clearance is within
groove of each piston as follows: (a) Place stainless
tolerance, you will feel a definite drag. Disassemble the
steel expander spacer in groove with ends butted.
rod cap and remove the shim stock. If clearance is not
(b) Install steel segment on top side of
within tolerance, replace the connecting rod bearings
expander spacer with gap of segment approximately 90
and recheck the clearance. If clearance is still not within
beyond gap of stainless steel expander spacer, making
tolerance, replace the crankshaft.
certain that the expander spacer ends are still in a
(12) Lubricate the crank pin bearing journals
butted position.
and the sleeve bearings with engine oil. Install the cap
(c) Install second segment on bottom side
(13, fig. 4-13) onto its connecting rod (20) and crank pin
of the
expander
spacer
with
segment
gap
bearing journal; secure with the two bolts (12) and nuts
approximately 90 from the expander gap in opposite
(11). Tighten the nuts to 40 to 45 footpounds (5.532 to
direction from which the top segment has been installed.
6.223 kgm) torque. Install the cotter pins (10).
(d) Recheck assembly. Rings should be
(13) Secure the remaining connecting rods to
free to move in the groove; however, you will notice a
the crank pin bearing journals.
slight drag because of the side sealing action of the ring
(14) Install the engine oil pan (para 4-5c) and
assembly.  Be sure expander spacer ends remain
oil pump (para 4-6c).
butted.
(15) Install the cylinder head (para 4-3r).
(7) Install the remaining piston rings on the
piston with a standard ring expander tool.
(8) Assemble
the
remaining
pistons,
4-10. Main Bearings and Crankshaft
connecting rods, and piston rings.
(9) Install  the  assembled  pistons  and
a.
Removal and Disassembly.
With the engine
connecting rods in the same cylinders from which they
mounted on an engine overhaul stand, proceed as
were originally removed.  Use a ring compressor to
follows: (1) Remove the cylinder head (para 4-3a).
compress the piston rings.  Lubricate the pistons and
(2) Remove the oil pan (para 4-5a) and oil
cylinder walls with engine oil before installing the
pistons. Wrap the bottom ends of the connecting rods
(3) Remove the gear cover (para 4-7a).
with cloths to prevent damage to the cylinder walls
(4) Remove  the  flywheel  and  flywheel
during installation.
housing (para 4-8a).
(10) Check the crank pin bearing journal-to
(5) Remove the pistons and connecting rods
connecting rod bearing clearance with plastigage. Lay a
piece of plastigage material on the crankshaft journal
(6) Remove the bolts (24 and 28, fig. 4-13)
and install the connecting rod bearing cap. Torque the
that secure the main bearing caps (25, 29, 32, and 34)
nuts to 40 to 45 foot-pounds (5.532 to 6.223 kgm).
to the cylinder block.  Loosen the bearing caps by
Remove the bearing cap and compare the width of the
tapping them with a plastic hammer.  Remove the
flattened plastigage material with the scale markings on
bearing caps and lower bearings (27, 30, 33, and 35).
the plastigage package to determine the clearance. The
bearing-to-journal clearance shall be 0.006 to 0.0022
NOTE
inch (0.0015 to 0.0055 cm).  If clearance is beyond
Upper main bearing shells can be removed without
removing the crankshaft.  To remove the upper shell,
these limits, replace the bearing and/or the crankshaft
remove the main bearing cap at the defective bearing and
as required.
remove the lower bearing shell.  Insert a pin with an
(11) As an alternate method of checking crank
angular head into the oil hole of the crankshaft as shown
pin
bearing
journal-to-connecting
rod
bearing
in figure 4-15. Rotate the crankshaft and roll the bearing
clearance, install a 1/2 inch (1.250 cm) piece of
shell from the cylinder block.
0.0022inch (0.0055 cm) thick feeler stock between the
4-16

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