TM 54310-227-15
(24). Drive out the low-pressure pis-
mum allowable wear or clearance is
ton pin and remove the low-pressure
0.001 inch.
connecting rod (23) from the low-
(5)
Inspect the connecting rods for any
pressure piston.
visible damage or misalinwnent. Re-
(11) Remove the two retaining rings (1)
aline slightly twisted rods or replace
that secure the high-pressure piston
if they are badly damaged.
pin (8) in the high-pressure piston
(6)
Place the piston rings in the cylinder
(7). Drive out the high-pressure pis-
bore in which they will be used and
ton pin and remove the high-pressure
measure tine ring gap with a feeler
connecting rod (10) from the high
gage. Position the piston ring square
pressure piston.
with the cylinder born about one half
(12) Press the sleeve bearings (9 and 25)
inch from the top. The correct gap for
from the connecting rods.
the small compression and oil rings is
0.012, plus or minus 0.005 inch.
if they need to be replaced.
(7)
If the ring gap is less than the speci-
fied, width, file across the butt ends
(13) Remove the connecting rod bearings
of the ring to increase the gap to the
(12) from the connecting rod caps
required tolerance. If the ring gap is
(18) and connecting rods (10 and
greater than 0.023 inch for any ring,
23) .
replace the entire set of rings.
Note. Match mark all parts to insure
(8)
Measure the ring groove in the pis-
correct reassembly.
t o n s for wear and side clearance,
(14) Use a suitable ring expansion tool and
using a feeler gage between the ring
start at the top piston ring on each of
and groove side wall. The desired
the pistons (7 and 24). Expand each
ring groove clearance is 0.0010 to
of the piston rings (3, 4, 5, and 6)
0 . 0 0 2 5 inch for the low-pressure
and work each ring from the ring land
rings and 0.0010 to 0.0045 inch for
of the piston, moving up and over the
the high-pressure rings.
top of the piston.
c. Assembly and Installation.
b. Cleaning, Inspection, and Repair.
(1) Install the piston rings (3, 4, 5, and
(1) Clean all parts with an approved
6) in the grooves in the pistons (7 and
cleaning solvent and dry thoroughly.
24). We a suitable piston ring ex-
(2) Inspect the cylinder for broken cool-
pansion two to expand each ring and
ing fins and cracks. Replace a dam-
move it down over the top of
aged cylinder.
the piston to the correct ring groove.
(3) Inspect the cylinder bores for wear,
Turn each piston ring so its ring gap
scoring, pitting, or other damage. In-
is 180 away from the adjacent ring
spect the bores, for out-of-round by
gap.
placing an inside micrometer in the
(2) Install the connecting rod bearings
top of the cylinder bore and taking
(12) in the connecting rods (10 and
t w o measurements, 90 apart. Re-
23) and connecting rod caps (18).
peat the procedure halfway down the
(3) Install the sleeve bearing (9 and 25)
The difference between the
bore.
in the connecting rods.
two measurements is the amount the
bore is out-of-round. Replace or re-
(4) Position the high-pressure piston (7)
size the cylinder if the bore is over
on the high-pressure connecting rod
0.002 inch out-of-round.
(10) and install the high-pressure pis-
ton pin (8) in the high-pressure pis-
(4) Measure the clearance of the piston
ton. Drive the high-pressure piston
pin in the piston pin bushing. Desired
pin through the sleeve beaning in the
clearance is 0.002 to 0,009 inch. Maxi-
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