115 Johnson V4 1983 bad cylinder

[RiverMan]

Hello again.<br />Now more problems!!! after a nice afternoon ride, got stuck on the way home. Pull boat out water and noticed a small metal parts on one of the spark plug. I open the R side head and found the bottom piston has melted on the head, damaged the wall of bottom cylinder and also the cylinder head. The top cylinder is on good condition, so the others on L side.<br />Now what??? is it possible to repair one cylinder :bore out, replace piston, rings, etc or all 4 cylinders a once. Therefore, last to junk it and start looking for another motor for my 19' BAYLINER TROPHY.<br />Please, will like to hear some suggestions.<br />Thanks....Board.<br />RiverMan

 

[BKool68]

Re: 115 Johnson V4 1983 bad cylinder

Yes you can replace just that cylinder if the other 3 are fine. I would recommend checking them all when torn down to make sure the problem was not spreading. A melted piston is a sign of a lean mixture. Do you premix? Might also be a plugged up high speed jet on your carb

 

[RiverMan]

Re: 115 Johnson V4 1983 bad cylinder

Yes, I premix the oil and fuel. On that day I used a 6 gallon of fuel that was left open outside on the heavy rain. But I was convinced that was ok. to use until I start having like carb. problems on that day. I brougth the boat home with the help of my br/law who keep squeezing the fuel bulb all way to the house. I did replaced the fuel pump with the kit, but still don't work it: them I found the metal on the spark and decided to open that side and found this problem. I will open the other side tomorrow, as you mentioned.<br />Thanks

 

[BKool68]

Re: 115 Johnson V4 1983 bad cylinder

It sounds as if fuel caused your problem. You will have to remove the power head to tear down and replace that piston. The tops of the other pistons may look fine but the sides may be burnt or scored. Removing the other pistons for inspection will be time well spent.