TM  10-3930-638-24&P 4-2.   ENGINE   MAINTENANCE   (cont) f. Pistons and Connecting Rods (cont). STEP LOCATION ITEM ACTION REMARKS CLEANING   (cont) WARNING Wear safety glasses when drying parts with compressed air, Fail- ure to do so could cause serious injury to eyes and possible blind- ness. If you hurt your eyes or if a foreign object is blown into your eyes, seek medical attention immediately. 6 All parts Clean 7 Piston (4) a.  Overall Clean b. Piston ring Clean groove c. Piston oil hole Clean INSPECTION 8 Piston(4) a. Overall Inspect b. Piston pin bore Measure diameter C. Oil ring side Measure clearance Use cleaning solvent P-D-680. Dry thor- oughly with moisture free compressed air or clean cloth Remove carbon from piston using care not to scratch piston Use groove cleaning tool Use small drill or fine wire Inspect  for  cracks,  damage,  scoring,  evi- dence  of  overheating  and  damaged  ring grooves.   If any of these conditions ob- served,  replace  piston Use bore gage and measure two places, 90 degrees apart. Replace piston if dia- meter is greater than 1.2508 inches Use  feeler  gauage.  If  measurement  exceed: 0.005 inch, replace piston 4-45