ARMY TM 9-2815-260-24
AIR FORCE TO 38G1-126-2
MARINE CORPS TM 09244A/09245A-24
Piston rings come pre-installed in new piston and liner assemblies. Leave
piston inside liner.
Install piston rings as follows:
Install oil ring expander in bottom ring groove of piston (4) using piston ring
expander. Position end gap of oil ring expander toward either side of piston pin.
Install oil control ring (7c.) in bottom ring groove over ring oil ring expander.
Position end gap of oil control ring on opposite side of piston from oil ring
Identify top side of compression rings (7a. and 7b.). Top side of rectangular and
keystone compression rings are identified by depression marks on top side of
Install rectangular compression ring (7b.) in center ring groove of piston (4)
with depression marks facing top of piston.
Position gap in rectangular compression ring (7b.) on opposite side of piston
from gap in oil control ring (7c.).
Install keystone compression ring (7a.) in top ring groove of piston (4) with
depression marks facing top of piston.
Position gap in keystone compression ring (7a.) on opposite side of piston from
gap in rectangular compression ring.
Measure piston protrusion as follows:
Press down on top of piston (4) to remove oil clearances before measuring
Position gauge on cylinder block. Zero dial indicator against cylinder block.
Position gauge across piston. While pressing gauge downward, rotate
crankshaft until piston is at Top Dead Center (TDC) position.
Measure piston height at several positions around piston. Piston Protrusion
(above cylinder block deck) should be 0.003 - 0.012 in. (0.08 - 0.30 mm).
If piston protrusion is out of specifications, check dimensions of piston, cylinder block,
crankshaft, and bearings to determine the cause.