Piston problem

[Stan9867]

Hello
I have a 2 carb 70 HP Mercury. Some of the metal on top of my upper piston left the piston and went between the skirt and cylinder wall. This jammed the rings and caused no compression on that cylinder. I replaced all three pistons. This was expensive I do not want the problem to recur, could anyone give me some idea on how to prevent this from happening.
Thanks
Stan

 

[James R]

Re: Piston problem

What is the year and model.

 

[Chris1956]

Re: Piston problem

stan, That is usually caused by lean fuel mix, over advanced timing, overheating or some combination of all three.

Clean the carbs and rebuild with new gaskets, replace the waterpump impeller and gaskets and seals and perform a link and synch and set idle and max timing properly.

 

[Stan9867]

Re: Piston problem

!986 70hp mercury

 

[Stan9867]

Re: Piston problem

Thanks
Stan

 

[James R]

Re: Piston problem

Stan. Chris has it. Don't forget to run on double oil for the breaking in period. Seems a lot but ten hours would be good. Use Stabil Marine in your fuel. That will help keep your fuel system clean and ensure that your cylinders are getting the correct amount of fuel and lube.

 

[Stan9867]

Re: Piston problem

I have also found a bad impeller. Two of the vanes were broken and the rest worn. Although I am sure the engine was pumping water. I guess not enough though.
Thanks again for the help.
Stan