824052R 2 Mercury SERVICE MANUAL

Illustration 1 g00845975 (1) The chamber that is on the top of the piston must face the right side of the engine. (2) The Shibaura name that is on the inside of the piston must align with the stamped number on the connecting rod. Piston and Piston Rings
Illustration 2 g00845969Use a feeler gauge to measure the clearance between the piston ring groove and the piston ring. If the clearance is greater than the service limit, use a new piston ring and check the clearance.If the clearance is within the service limit, renew the piston rings. If the clearance is outside of the service limit, renew the piston. (1) Top piston ring Shape of top ring (A) Naturally aspirated ... Barrel faceTurbocharged ... Half keystoneC0.5 and C0.7 Clearance between piston ring groove and top piston ring ... 0.06 to 0.10 mm (0.0024 to 0.0039 inch)Service limit for clearance of top piston ring ... 0.25 mm (0.0098 inch)Gap of top piston ring ... 0.13 to 0.28 mm (0.0051 to 0.0110 inch)Service limit for gap of top piston ring ... 1.0 mm (0.039 inch)C1.1 and C1.6 Clearance between piston ring groove and top piston ring ... 0.08 to 0.12 mm (0.0031 to 0.0047 inch)Service limit for clearance of top piston ring ... 0.25 mm (0.0098 inch)Gap of top piston ring ... 0.20 to 0.35 mm (0.0079 to 0.0138 inch)Service limit for gap of top piston ring ... 1.0 mm (0.039 inch)C1.5 and C2.2 (Naturally Aspirated) Clearance between piston ring groove and top piston ring ... 0.07 to 0.11 mm (0.0028 to 0.0043 inch)Service limit for clearance of top piston ring ... 0.25 mm (0.0098 inch)Gap of top piston ring ... 0.20 to 0.35 mm (0.0079 to 0.0138 inch)Service limit for gap of top piston ring ... 1.0 mm (0.039 inch)Note: It is difficult to measure the wear of the top piston ring on the C1.5 (Turbocharged) and C2.2 (Turbocharged) engines. When either the intermediate ring or the oil control ring is outside the service limit, renew all of the rings.Note: Install the word "T" or "RN" toward the top of the piston. New top piston rings have a red identification mark which must be on the left of the ring gap when the top piston ring is installed on an upright piston.Note: New top piston rings for the C2.2 (Turbocharged) have a yellow identification mark which must be on the left of the ring gap when the top piston ring is installed on an upright piston.Note: The top surface of the piston ring should be equally distant from the top face of the cylinder block at all points before the piston