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Mayday mechanical


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Out for a few days, and shutting motor down, she was making some odd noises. Wouldnt start this am,took tappet cover off, and big spanner on flywheel and turn her (check tappets ok)and turns free then comes to a sudden stop! Help please. Should I try turning her backwards?

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Unfortunately spun her over on the starter this am. Cant be helped. Yes can rock her but then she comes to the spot where she stops. What are the bad scenarios? What tests before head off? Dread sailing home -20m. Wind here so fluky

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Sorry Vic. this doesn't sound good. A solid dead stop means a serious obstruction. Scenarios...... Valve head broken and fallen into cyclinder. Conrod has broken and is jamming against the bottom of bore. Crankshaft is broken. Cam must be OK if you saw all tappets working, so that's ruled out. A bolt has come out of Big end bearing and jammed.
You should find that in all scnearios, the engine will stop at same point. Mark the flywheel and buy hand, if you turn flywheel backwards, does it jam at ruffly same position. If yes, then any of the above are possible.
If not, then it could be a component in part of the engine that is geared down. Like the Fuel pump for example, may jam at fourth Revolution or some other random point.
No matter what, sorry but you are going to need a tow home, or sail it home if conditions are right for you.

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Could be worse, pretty easily fixed then. Examine the valve and seat, the valve might be bent. Is there a dent in the associated piston? If not, re-lap the valve and seat with valve grinding paste, and ensure the seal on both comes up ok.

If it does, then new gasket, re-assemble. Find where the screw came from, and locktite it back in ( if it’s serviceable). Have a great summer boating,

If it doesn’t, the head will have to go to a machine shop to have the seat and valve re-done.

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Poor screw flattened as.Danged if know where from. Must have been sitting in the cleaner, but no empty holes. Indents in piston top that I,ve smoothed down, but still there. Gave head to reconditioners.

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Is there a butterfly valve in the inlet manifold? They are generally held in place with a smallish machine screw holding them to the pivot shaft. If there is and the screw has done what it has done and is missing the next thing to travel towards the valve could be the butterfly plate.

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