Hello All,
I have been using this forum and the invaluable amounts of intel that it provides but have yet to post. I purchased a late 60's early 70's Mark Twain V Sonic Tri Hull with a Mercruiser 160 hp I6 motor but I simply call it the 165 because it is basically the same.
I bought this bad boy for $350 because the working parts and trailer were worth more than that. So here is what I am currently dealing with. Last year I had the gimbal bearing and boots replaced. Prior to doing that I had the mechanics "run" the motor to see if it fired up and would run to give an opinion of whether the engine was worth putting work into. They said they started it and I went ahead with the repair. Fast forward to this year.
I pulled off the cover and begun to hook up my new fuel system. Since I purchsed this boat I have rebuilt the carb twice. Ethanol gotta love it. So I pulled the tanks gave them a bath inside and out had them tested for viability as tanks. They are good to go. I then put in new lines and added an inline fuel water seperator. I did not fire this bad boy up last year because I needed a flexible fuel fill hose to connect the inlet s to the tanks. The offset was to great for standard fuel fill. I got it over the winter and put everything back together. I hooked up the battery and water and turned the key...CLICK. No turning of the motor. The motor was not turning just the click.
I have the shop manual. I got out the test light and checked the slave solenoid. I thought that it tested bad so I bought a new one. Put it in and got the same thing...Click. I also got the same results on the light. According to the guide I used from this site it said it was wrong. I might have done something wrong let me know:
Next I moved to the starter. I pulled it and bench tested it. It works great. Pops out and spins with no proplem.
Now I am dreaded that the motor is seized. I tried pb blaster in the spark plug holes for a couple of hours andd nothing changed. Three plugs had significant rust. So:
As far as the head and manifolds, I did an electrolysis bath. That is an awesome process that has worked wonders. I highly recommend that. I have yet to find any cracks in the manifold or head. I did find a crack in the block over the water jacket.
Before everyone sighs and says junk it and start fresh, that isn't happening I need suggestions based upon current discovery and willingness to do the best with JB Weld or similar. I have drilled out the crack, dremmelled it and cleaned the hell out of it. JB Weld can work depending upon expectations. With that being said, I have yet to try and crank this motor since I have taken apart. I don't want to take this motor out just yet. Breaker bar? The pulley is behing motor mounts. Is there enough room to wiggle the crank. Also I drained the oil and there was about a quart of water that came out then oil. Is it possible for the crank to seize? How likely? Afterall water is heavier than oil and sits on the bottom of pan. Crank theoretically should have been in a poor quality oil. Should have protected enough for sitting.??? I will post more pics soon. Apologize for the length but trying to be thorough. Also should I pull the outdrive b4 trying to turn engine? If the engine will work and the outdrive will work I will move to the interior restore next. Please help folks. Again I know a new engine/boat would be better but that is not productive. I want to take this as far as I can. And I can take things very far on my own.

I have been using this forum and the invaluable amounts of intel that it provides but have yet to post. I purchased a late 60's early 70's Mark Twain V Sonic Tri Hull with a Mercruiser 160 hp I6 motor but I simply call it the 165 because it is basically the same.
I bought this bad boy for $350 because the working parts and trailer were worth more than that. So here is what I am currently dealing with. Last year I had the gimbal bearing and boots replaced. Prior to doing that I had the mechanics "run" the motor to see if it fired up and would run to give an opinion of whether the engine was worth putting work into. They said they started it and I went ahead with the repair. Fast forward to this year.
I pulled off the cover and begun to hook up my new fuel system. Since I purchsed this boat I have rebuilt the carb twice. Ethanol gotta love it. So I pulled the tanks gave them a bath inside and out had them tested for viability as tanks. They are good to go. I then put in new lines and added an inline fuel water seperator. I did not fire this bad boy up last year because I needed a flexible fuel fill hose to connect the inlet s to the tanks. The offset was to great for standard fuel fill. I got it over the winter and put everything back together. I hooked up the battery and water and turned the key...CLICK. No turning of the motor. The motor was not turning just the click.
I have the shop manual. I got out the test light and checked the slave solenoid. I thought that it tested bad so I bought a new one. Put it in and got the same thing...Click. I also got the same results on the light. According to the guide I used from this site it said it was wrong. I might have done something wrong let me know:
- held light to left terminal with yellow/red wires - glowed with no crank went out with crank
- far right terminal held light to the nut and nothing with or without crank
- tried the other two terminals and got nothing.
Next I moved to the starter. I pulled it and bench tested it. It works great. Pops out and spins with no proplem.
Now I am dreaded that the motor is seized. I tried pb blaster in the spark plug holes for a couple of hours andd nothing changed. Three plugs had significant rust. So:
- pulled the exhaust/intake manifold (some rust in the ports)
- pulled the cylinder head
- pulled the rods first and they are straight and look solid.
- The valves and head is a different story.
As far as the head and manifolds, I did an electrolysis bath. That is an awesome process that has worked wonders. I highly recommend that. I have yet to find any cracks in the manifold or head. I did find a crack in the block over the water jacket.
Before everyone sighs and says junk it and start fresh, that isn't happening I need suggestions based upon current discovery and willingness to do the best with JB Weld or similar. I have drilled out the crack, dremmelled it and cleaned the hell out of it. JB Weld can work depending upon expectations. With that being said, I have yet to try and crank this motor since I have taken apart. I don't want to take this motor out just yet. Breaker bar? The pulley is behing motor mounts. Is there enough room to wiggle the crank. Also I drained the oil and there was about a quart of water that came out then oil. Is it possible for the crank to seize? How likely? Afterall water is heavier than oil and sits on the bottom of pan. Crank theoretically should have been in a poor quality oil. Should have protected enough for sitting.??? I will post more pics soon. Apologize for the length but trying to be thorough. Also should I pull the outdrive b4 trying to turn engine? If the engine will work and the outdrive will work I will move to the interior restore next. Please help folks. Again I know a new engine/boat would be better but that is not productive. I want to take this as far as I can. And I can take things very far on my own.

