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 (7) Inspect valves (28 and 34). Replace a bent or worn
b.
Maintenance, Removal, Repair and Installation.
valve.
Maintenance of the oil cooler is identical to that of the water
(8) Remove crankcase inspection plates on each side
cooling heat exchanger. See paragraph 3-21 for details,
of the engine. Wash out the sump with clean fuel oil and wipe
except, substitute "oil" for "fresh water".
dry. Inspect all lubrication oil lines. Replace a damaged oil
line.
3-24. Crankshaft, Main Bearings and Crankcase
(9) Remove the lubrication oil strainer. Wash the
Explosion Valves
strainer in clean fuel oil, then reinstall the strainer.
a. General. The crankshaft is made of forged steel and
(10) Examine the lubrication oil thermometer. Replace
supported by main bearings of the interchangeable shell,
a defective thermometer.
babbitt type. These must be scraped and lapped when
e. Reassembly. Assemble the lubrication oil pump in
installed to give a good bearing surface. The purpose of the
reverse order of disassembly, using new gaskets in all places.
crankshaft is to convert the reciprocating movement of the
f. Installation.
(1) Slide bracket (8) over studs (5) and mesh the gear
are located on the crankcase inspection plates. The purpose
(15) with the oil and water pump drive.
of the explosion valves is to relieve pressure in the crankcase
(2) Install housing (21) by sliding plate (7) over studs
should combustion ever take place or excessive pressure
(5). Use a new gasket between plate (7) and bracket (8).
build up.
(3) Align the couplings (17 and 18).
b. Removal.
(4) Install nuts (6) and tighten.
(1) Prior to removing main bearings, check bearings for
(5) Bar engine over slowly to make sure the lubrication
clearance. Slip a feeler gage between the crankshaft and the
oil pumps works freely.
bearing cap. The proper clearance is from .004 to .006 inch.
(6) Connect the suction and discharge oil lines to the
When the clearance is found to be excessive, remove
pump.
sufficient shims from each side of the bearing. Example:
(7) Open shutoff valves in suction and discharge lines.
Where the clearance is found to be .012 inch, remove a .006-
(8) Reinstall the crankcase inspection plates.
inch shim from each side of the bearing. Excessive clearance
may be indicated by loss of pressure in the lubricating oil
3-23. Lubrication Oil Cooler (Heat Exchanger)
system. The thickness of the main bearing shims are as
a. General. The lubrication oil cooler is a two pass heat
follows: .006, .020 and .064 inch. It is good practice to
exchanger mounted horizontally on starboard side of engine
replace the main bearings when the clearance is found to be
room, just aft of the water cooling heat exchanger. The raw
in excess of .030 inch.
water enters the cooler and flows through the tube bundle and
(2) Remove the appropriate crankshaft inspection
out to the water cooling heat exchanger. The lubrication oil
plates on each side of engine.
flows through the housing and over the outside surfaces of the
(3) Remove cotter pins and back off stud nuts (9, fig.
tube bundle. The purpose of the cooler is to remove engine
heat from the lubrication oil. A bypass valve and line is fitted
Remove and tag shims (10) for proper reinstallation
to the cooler to provide a path for oil, should the housing
identification.
become clogged. Zinc protector plates (anodes) are located
in the cooler to compensate for the electrolytic action of the
raw water.
3-61
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