My 77 Evinrude 70 HP (70773S) failed yesterday. Did not overheat but I believe that there must have been a cracked ring in cylinder #2. The motor was running well at 3/4 throttle when it gradually lost RPM and quit. Starter would engage flywheel but not spin the motor. Attempt to turn flywheel revealed motor almost siezed. When got boat home pulled spark plugs thinking maybe hydraulic lock from leaky gasket but plugs one and three normal and two had been smashed by something. I pulled the head to find pieces of metal and shavings imbedded in the top of the #2 piston and cylinder head area for #2 cylinder. The debris was pretty ground up and appeared to be the remnants of a piece of piston rign One and three were ok. Not much scoring between the exhaust ports and the top of the cylinder. I pulled the exhaust housing and the #2 piston side did not show any scoring on the piston side, The engine is still hard to turn which leads me to believe there is damage on the inward side of the exhaust ports for #2 Cylinder. I won't get time to dissamble the thing for a week or two but I'm curious what I will find. I would like to rebuild this engine this winter if the damage is not too extensive. I won't know until its torn down. I really liked that motor. I have had it for about five or six years. The boat, motor and trailer did not cost me $1500.00 and I used the daylights out of it since I bought it. I am going to try and post a couple of pictures of the damage. I appreciate any input.
Tony
Tony