Mercury Mariner 4, 5, and 6HP 4-Stroke Factory Service Manual, Page 156Get this manual
CYLINDER BLOCK AND CRANKCASE
Measuring Piston Ring End Gap
Standard Value Top Second Oil 0.0060.014 in(0.15 0.35 mm) 0.0120.020 in(0.30 0.50 mm) 0.0080.016 in(0.20 0.40 mm) Out of the Limit If 0.020 in(0.5 mm) or more requires replacement If 0.028 in(0.7 mm) or more requires replacement If 0.024 in(0.6 mm) or more requires replacement
Push piston rings into cylinder approximately 0.8 in(20 mm) deepPush in the rings using the piston