1996 225hp Mercury Offshore O/B. Ran fine last year -came out of the hole and planed fast, reached max RPM's (5500) with no problem. Then spun hub and replased. A couple of trips later -a loud knocking noise from gearcase. Shop disassembled and gear teeth were chipped -did not hit anything, no water in lube -unknown cause. Ordered new gearcase off iboats. Old L/U and new have same gear ratio (checked both twice), used original prop. Test run with new L/U yesterday and have difficulty getting up and planing (normal weight load). Moved two people to front of boat and it slowly came up; also triming motor up slightly helped. Once planing runs and sounds great, except that it maxes at 4800 RPM's. Checked for plug wire loose, will check plugs themselves and compression this evening. Changed fuel filter right before test run. Prior to damage to gearcase, no problems, compression consistent. Maybe damaged gearcase cause more problems than just to the L/U? Shouldn't have to re-prop -original prop worked well -same gear ratio on new L/U. New L/U has extension kit with coupler where old one was solid shaft -shouldn't make a differene right? Any advice is greatly appreciated.
