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 (8) Inspect the rods (5 and 6). Replace rods that are
(5) Remove all nuts (27) and lift off cover (28).
bent, or have damaged threads.
(6) Remove cylinder head (29) and gasket (26).
(7) Remove guide (3) and spring (2).
(8) Remove nut from rod (5) and lift out seats (4).
NOTE
Remove rods (5 and 6) and air valve seat assembly.
Before beginning reassembly of the
(9) Remove 2 nuts (20) and bolts (18). Tag nuts and
scavenging pump, service the crankcase
bolts for installation identification. Remove nuts from the
breather as described in paragraph 3-17
two bolts (17), then remove cap (19) and shims (16). Tag
below.
shims for installation identification.
(10) Remove piston (25) and rings, connecting rod and
d. Reassembly.
connecting rod bearing.
(1) Position connecting rod in the piston (25) and install
(11) Remove rings (10 and 11), spring (12), seat (13),
the pin (8).
and rings (14 and 15) from the air valve pump assembly.
(2) Replace the rings (22 and 23).
Expand the rings only as far as necessary to remove them.
(3) Position rod and piston assembly in the sleeve and
c. Cleaning, Inspection, and Repair.
lower the assembly until the rod rests on the rod bearing. Be
(1) Use a wire brush and remove carbon from cylinder
sure holes in bearing line up with those in the rod, then
head (29).
replace bolts (18) and nuts (20). Tighten the nuts evenly.
(2) Wash all parts in clean fuel oil and wipe dry with a
(4) Replace rings (10 and 11), spring (12), seat (13),
lint free cloth.
and rings (14 and 15). Install the air valves in the scavenging
(3) Inspect the piston (25). Replace a piston that is
pump cylinder and replace rods (5 and 6). Tighten the nuts.
cracked, or out-of-round.
(5) Replace the spring (2) and guide (3). Use a new
(4) Inspect the rings. Use a micrometer and measure
gasket (26) and replace the cylinder head (29). Tighten nuts
thickness of an old ring, then measure a new ring. If the
securing cylinder head evenly.
difference in thickness is 0.002 in. or more, replace the rings.
(6) Replace top cover (28) and tighten nuts (27)
(5) Remove pin (8) and key from the connecting rod
securing cover evenly.
sleeve bearing (7). Wash and wipe dry then insert pin in
(7) Use a new gasket, then install housing (1) and
bearing for measurement. If a feeler gage shows more than
tighten nuts evenly.
0.003 in. clearance between pin and bearing, replace the
(8) Refill expansion tank and the engine cooling
bearing (7).
system.
(6) Inspect the pin (8). Replace a pin that is pitted or
(9) Install the inspection plates on both sides of the
scratched.
scavenging pump.
(7) Inspect the connecting rod bearings and cap (19).
(10) Run the engine at half speed for 10 minutes, check
If bearings are pitted or cracked they must be. replaced. To
the scavenging air pressure, then stop the engine.
fit a new connecting rod bearing proceed as follows:
(11) Remove one inspection plate and check the
(a) Wash the crankshaft journal surface with clean
scavenging pump connecting rod bearing.
Feel of the
fuel oil and wipe dry. Cover journal with a light coat of
bearing. If the bearing feels hot to the touch, remove the
prussian blue. Place bearing (top half) on crankshaft. Install
bearing and check the lube oil supply passage for a possible
shims (16) and cap (19). Install bolts (17) and nuts, and
clogged opening.
tighten them evenly. Rotate bearing one half turn back and
(12) Start the lube oil standby pump and watch for oil
forth. Remove bearing and cap. Examine the bearing
to flow out of the passage in journal. If lube oil does not flow
surfaces. When bearing surfaces are 80 percent covered with
out of the passage, use a wire and remove the blockage.
blue, it indicated good (adequate) face-to-face contact with
When oil is flowing, stop the pump and install the bearing.
the journal.
(13) Replace the inspection plates and start the engine.
(b) Wash journal and bearing surfaces to remove
Recheck the connecting rod bearing as described in steps
blue and wipe dry.
(11) and (12) above.
(c) Use four strips of 0.010 in. soft lead wire under
e. Hand Lubrication Pump. Normal lubrication to the
bearing cap (they may be held in place by dabs of grease as
scavenging pump piston sleeves is from the force feed
cap is installed). Be sure that bolts tighten cap down evenly,
lubricator. To furnish this lubrication before the engine is
then remove cap. Measure thickness of the lead wire. When
started, use the hand lubrication pump that is mounted near
the bearings are new, wire should have compressed to
the scavenging pump, as follows:
between 0.003 and 0.005 in. If clearance is less than 0.003
(1) Fill the pump with oil through the port on top of
in., add shim. If over 0.005 in. remove a shim.
pump.
(d) When bearing is fitted to crankshaft with proper
clearance, leave it installed for the moment to prevent
damage to bearing or journal.
3-50
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