ARMY TM 9-2815-259-24
AIR FORCE TO 38G1-125-2
MARINE CORPS 09249A/09246A-24
The following procedure is provided for repairing the pistons and connecting rods. Remove pistons and
connecting rods (refer to paragraph step a. above) and place on a suitable workbench. Disassemble per the
(1) Disassemble the pistons per the following steps:
Remove piston (4, Figure 5-72), refer to step a.
Remove piston rings (7) using Piston Ring Expander.
Remove snap rings (8) using snap ring pliers. Discard snap rings.
Remove piston pin (9) and rod (5).
(2) Test the pistons and connecting rods per the following steps:
Clean piston ring grooves using piston ring groove cleaning tool.
Compressed air used for cleaning can create airborne particles that can
enter the eyes. Pressure must not exceed 30 psi (207 kPa). Eye protection
When washing pistons, always use a stiff bristle brush, not a wire brush, to
loosen carbon residue. Failure to comply could result in damage to pistons.
Clean pistons (4, Figure 5-72) with hot water and liquid detergent. Soak pistons in a
solution of 50 percent liquid household detergent and 50 percent hot water for 30 to 60
minutes. Use stiff bristle brush to loosen carbon residue. Dry with compressed air.
Carefully inspect pistons (4) under magnification. Check for the following: signs of
fatigue, fine cracks in piston head (1, Figure 5-73), bent or broken ring lands (2), cracks in
skirt (3) at inner and outer ends of piston pin bore, and excessive piston skirt wear.
(Original machining marks must be visible.). If any imperfections are found, replace piston
(4) and cylinder liner (11, Figure 5-72), refer to paragraph 5.4.6, as a set.