Engine starting problems

I am new to this boat restoration stuff and posted another question earlier so bear with me. 1991 Baja Islander 225 with a 5.7L Yamaha (GM engine, mostly). New deep cycle batt installed, batt cables have some green corrosion. Engine cranks for a few revolutions and then stops with a "clank" sound. This just started as the engine used to turn over and run but had a cooling problem. I replaced the impeller and it seems to pull water now then this "clank" started. When I hear the sound the engine stops cranking but if I turn the key off then try to crank again it will followed by another "clank". Help! Appreciate any info.<br />Also, this boat had sat off and on for years as I bought it for a project. I think a mud-dobbers nest was somewhere near the engine water pump because it broke and dropped into the bilge area and as it weird as it sounds that's when this "clank" started. Engine ran fine before (except for cooling problem).

Re: Engine starting problems

Pull the plugs and then crank it to see if any water comes out of the spark plug holes.....could be hydrolocking as a result of the cooling problem.

Re: Engine starting problems

Thanks. I will check that and add it to my "to do" list for the boat.