Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-42794--1, Page 142Get this manual
Sliding Clutch 1Inspect sliding clutchCheck reverse gear slide clutch jaws, if jaws are rounded replace as necessaryRounded clutch jaws can be caused by the followingImproper shift cable adjustment Engine idle speed (RPM) too high when shifting Shifting outboard from neutral to reverse too slowly
Water Pump Components
1Inspect impellerReplace impeller if any of the following conditions exist: Impeller blade(s) are cracked, torn, or worn Impeller is glazed or melted (caused by operation without sufficient water supply) Rubber portion of impeller is not bonded to impeller hub