INSPECTION OF PISTON AND CONNECTING ROD ASSEMBLIES 1. CLEAN PISTON (a) Using a gasket scraper, remove the carbon from the piston top. (b) Using a groove cleaning tool or broken ring, clean the ring grooves. (c) Using a soft brush and solvent, thoroughly clean the piston. NOTICE: Do not damage the piston. 2. INSPECT PISTON DIAMETER AND OIL CLEARANCE (a) Using a micrometer, measure the piston diameter at a right angle to the piston pin hole center line, 22 mm (0.87 in.) from the piston head. HINT: There are five sizes of standard piston diameter, marked "0", "1", "2", "3" and "4" accordingly. The mark is stamped on the piston as shown in the illustration. 7M-GE Front Mark Front Piston Size Mark (0, 1, 2, 3 or 4) EM5543 EM5426 EM5527 EM17302 EM5744 22 mm