ARMY TM 9-2815-260-24 AIR FORCE TO 38G1-126-2 MARINE CORPS TM 09244A/09245A-24 5-73 (c) Remove snap rings (8) using snap ring pliers.  Discard snap rings. (d) Remove piston pin (9) and rod (5). (2)   Test the pistons and connecting rods per the following steps: (a) Clean piston ring grooves using piston ring groove cleaning tool. __________ WARNING Compressed air used for cleaning can create airborne particles that can enter the eyes.  Pressure must not exceed 30 psi (207 kPa).  Eye protection required. CAUTION 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. (b) 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. (c)   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. (d) Check piston ring groove wear as follows: 1 Check wear of keystone ring groove (top groove) using Ring Groove Wear Gauge (JDE62).  Check groove at several locations around circumference of piston.  Gauge shoulders should not contact ring land.  Clearance (1, Figure 5- 74) between shoulders of Ring Groove Wear Gauge (2) and ring land indicate ring groove is good.  If ring groove is worn, replace piston (4, Figure 5-72) and cylinder liner (11), refer to paragraph 5.4.6, as a set.