1980 Johnson 115, bad piston

[Robert Harris]

I posted a few days ago, but it got wiped before I could check back.My question is I just bought my first boat and I knew it had motor problems.I pulled the head on right side to find the bottom piston chewed up which scored the cylinder and damaged the head.I have heard several different opinions on what is best to do.Some people say just fix the bad cylinder, other people say to bore and replace all 4.I do not have much experience with outboards, mostly auto.<br /><br />Any help would be appreciated, Thanks

 

[DJ]

Re: 1980 Johnson 115, bad piston

RH,<br /><br />You can go either way. Remember, when you're done you'll still have a 23 year old motor. It may very well be worth it, if the rest of the engine is in good shape and you like it.<br /><br />You can figure about $200.00 per cylinder to rebuild.<br /><br />Make sure that the root cause for the failure is found during the rebuild.

 

[Robert Harris]

Re: 1980 Johnson 115, bad piston

Thanks for the info.I plan to install new water pump kit and rebuild carbs at same time.Are these the two main culprits for piston failure?<br /><br />I'll have to read all responses later, I have to go do that work thing. <br /><br />Thanks for your time.

 

[Dhadley]

Re: 1980 Johnson 115, bad piston

Once you measure the cylinders you will know what you are going to bore. If the other three are in spec, you will bore one. If not.......<br /><br />I'll bet the damage is from coking. I'd also bet that if the motor is all standard now, it'll need all 4 bored. Hopefully #3 will clean at .020.<br /><br />Keep us informed. Even if we get erased.

 

[RPJS]

Re: 1980 Johnson 115, bad piston

RH,<br />I have only just finished a rebuild on a V4 for the same problem you have #3 piston in a bad way. I only bored the 1 piston but also de glazed the other 3 pots. The damage to my motor was caused by carbon build up on the rings which I put down to bad maintainance by the previous owner. A bit of advise I was given while doing the rebuild was to ensure that no little bits of ring were embeded in the head, they will cause hot spots when the motor is running leading to pre ignition and engine damage.

 

[Robert Harris]

Re: 1980 Johnson 115, bad piston

Thanks for the advice.Now I have to start making decisions.I'm too cheap or maybe just to poor to do the right thing and take it to a shop and say "fix it" One marina wanted 225.00 bucks to break it all down and then tell me what I need.I'm new to this game so I just don't understand why this outboard stuff is so expensive.<br />I will have to rebuild myself with a good manual or does anyone have any experiemce with those complete rebuilt powerheads you see on the internet?<br /><br />Thanks

 

[DJ]

Re: 1980 Johnson 115, bad piston

RH,<br /><br />Get the manual and try it yourself. You might enjoy it. You'll aprreciate having the manual around regardless of which way you go.