hi all seem to be having problems with my 1977 80 hp outboard awhile back i heard what i thought was a knocking or banging noise coming from engine(soo i thought) i got a manual and took apart powerhead comepletly what i found was #4 (bottom piston) was clean and so was sparkplug water had gotten in through a bad exhaust casket i check all internal parts and found no damage pistons crank rings bearings all were in gr8 shape i put all new gaskets on and reassembled the motor i installed it and it started right away it ran better than it ever did next was a water test i launched the boat and as soon as i took off the banging noise was still there obviosly there is a prob somewhere else 
i take it there was a prob with the motor because of the water in #4 so that prob is now fixed so that leaves lower unit i did notice a white or milky substance coming out around the prop area so i fiqure its shot it does shift into gears allright no clunking at all my question is can i replace the gears and seals are am i going to have to replace the whole unit or is there something i,m missing here that i,ve over looked this was my first time doing a outboard motor so i,m happy the motor runs real nice its fustrating i,m leaving for a fishing trip on thur and now boat is f______d any help in diagnosing this prob would be appriciated thx
i take it there was a prob with the motor because of the water in #4 so that prob is now fixed so that leaves lower unit i did notice a white or milky substance coming out around the prop area so i fiqure its shot it does shift into gears allright no clunking at all my question is can i replace the gears and seals are am i going to have to replace the whole unit or is there something i,m missing here that i,ve over looked this was my first time doing a outboard motor so i,m happy the motor runs real nice its fustrating i,m leaving for a fishing trip on thur and now boat is f______d any help in diagnosing this prob would be appriciated thx