TM 5-4320-302-14 6-16. PISTON ASSEMBLY (CONT) Location/Item Action Remarks Piston   rings   for   the   correspondingly   sized   pistons   and cylinders are also available in normal and two oversizes: PISTON RING FIRST TRAPEZOIDAL SECOND TAPER PISTON THIRD OIL CONTROL (outside diam- RING RING RING eter x inside DIMENSIONS DIMENSIONS DIMENSIONS diameter x inches inches inches width) (millimeters) (millimeters) (millimeters) 3.9370 x 3.5984 x 3.9370 x 3.5984 x 3.9370 x 3.5787 x Normal 0.1181 0.0984 0.1969 (100.0 x 91.4 x 3.0) (100.0 x 91.4 x 2.5) (100.0 x 90.9 x 5.0) 3.9567 x 3.6181 x 3.9567 x 3.6181 x 3.9567 x 3.5984 x First oversize 0.1181 0.0984 0.1969 (100.5 x 91.9 x 3) (100.5 x 91.9 x 2.5) (100.5 x 91.4 x 5.0) 3.9764 x 3.6378 x 3.9764 x 3.6378 x 3.9764 x 3.6181 x Second oversize 0.1181 0.0984 0.1969 (101.0 x 92.4 x 3.0) (101.0 x 92.4 x 2.5) (101.0 x 91.9 x 5.0) REPLACEMENT OF PISTON, PISTON PIN, PISTON RINGS, OR CYLINDERS CAUTION Pistons, piston rings, and cylinders must always be matched to the same size or oversize.  Failure to match all three in size could cause serious damage to the engine. 19.  Piston Replace   piston   if   tin   plate   or   ring   grooves   are excessively    worn    or    damaged,    ring    lands    are damaged,  piston  is  heavily  scored  or  cracked,  or piston     shows     signs     of     excessive     overheating. Replace  piston  if  skirt  diameter  or  out-of-round  is not  within  tolerance.    If  piston  ring  side  clearance exceeds the limit, replace piston.  If piston pin bore is  not  within  tolerance  or  is  out-of-round,  replace piston. 6-119