1971 Mercury 500 Thunderbolt leaking from water jacket and snapped bolts on water jac

Joined
Nov 29, 2012
Messages
15
Hello all,
I have a 71 Mercury Thunderbolt outboard, I got it with a boat I purchased in the fall, I put gas in it pulled it a few times and it fired right up. At first it looked fine then I noticed a considerable amount of water coming out of the top spark plug hole. With closer inspection I see that it is coming out between the water jacket (I think thats what it is) and the head were the spark plug threads into. When i rev the motor I get more water, I get little water from the pee hole when idling but when I rev the motor I get a steady stream from the pee hole. I only ran the motor for maybe 30 seconds at a time about 3 or 4 times. I dont think there is actual water in the cylinder, I didnt run the engine long but the spark plug didnt look steam cleaned. How long should I run the motor for the plug to get steam cleaned.
Three bolts are snapped off on the water jacket, they are attached to a nut on the back side, can I use a punch to push these through or are they threaded? I have put penetrating oil on all the bolts now and letting them soak.
So do you think the gasket on the water jacket is shot? If so whats the best way to go about extracting these snapped bolts? Sorry this is so long I hope you guys can help me.
Thank You,
Charles
 

Laddies

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Sep 10, 2004
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12,218
Re: 1971 Mercury 500 Thunderbolt leaking from water jacket and snapped bolts on water

The bolt holes are drilled not tapped and the water is leaking around the water jacket cover gasket replace it and you should be good
 
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