i have 1985 four winns 170 horizon. the boat originally had a mercusier 170 in it. the engine was blown and removed by the previous owner. i install a rebuild 470 in the boat and have been working out all the kinks. the engine is great but the outdrive is what giving me the problem. i just replaced the exhaust bellow and the impeller. i was out driving it last night when i heard a loud clunk from the outdrive and the engine rev up while still in gear. i could only go about 10mph any faster and it would slip. when i spun the prop by hand in neutral there was a soft grinding from behind the prop. What is wrong?
