Connecting Rods and Pistons/Pistons and Connecting Rods 6. Measure piston ring groove width. Measure several places around each piston. PISTON RING GROOVE SPECIFICATIONS Item New Part Wear Tolerance M36393 -UN-29JAN90 Top Ring 2.032—02.057 mm 2.21 mm (0.080—0.081 in.) (0.087 in.) Second Ring 2.032—2.057 mm 2.21 mm (0.080—0.081 in.) (0.087 in.) Oil Ring 4.775—4.801 mm 4.95 mm (0.188—0.189 in.) (0.195 in.) If ring groove width exceeds wear tolerance, replace piston. M98,2030K,24 -19-11NOV85 CTM2 (19APR90) 30-15 16, 18, 20 & 24HP Onan Engines AllTractorManuals.com 130495 7. Inspect piston for worn or cracked ring lands.
Excessive piston wear near the edge of the top ring land indicated preignition. 8. Clean and inspect oil holes in oil ring groove for a plugged condition. Replace parts as necessary. -UN-29JAN90 M36394 M98,2030K,25 -19-09OCT85 30 15