Johnson 15 - scored piston and delaminating crankcase

[wineyarders]

Hi,

Building on a recent thread I started (http://forums.iboats.com/showthread.php?t=525675&p=3569412#post3569412) when I found some scoring in the lower cylinder of my '85 Johnson 15. After taking it apart the lower pistons is scraped up pretty good and needs to be replaced, but before I do that I want to be sure I'm not throwing money at a problem without fixing it. The dowel pin in the cylinder block (the pin that secures the crank) looks like it broke some material on the inside of the lower cylinder (see pic), meaning it was forced through the block by the crankshaft. The pin is not protruding into the cylinder at all, and the crankshaft seems to sit securely in it still. Not sure how this would happen, or if this is unusual. It would also explain why only the lower piston/cylinder has any damage. Can this be patched? Any thoughts? Also, the material around the lip of both cylinders on the crankcase side is eroding a little (see photo), which looks like it is causing material to break off (and in all likelihood enter the cylinders and cause damage). Only the bottom piston and cylinder have any apparent damage though, so not sure if this is a problem. Anybody have any thoughts? Thanks,

Ryan

 

[sutor623]

Re: Johnson 15 - scored piston and delaminating crankcase

Do you have a machinist near you? If you do I would take the crankshaft in as well as the cylinders and ask them if they think that they are useable. Sometimes the journals on crankshafts develop an uneven wear, that if not properly addressed will create uneven bearing, piston, and/or cylinder wear on the rebuilt motor. Honestly, I used to rebuild Honda/Acura B series motors, and often times when the compression was uneven for a long period of time as was in your motor, the crankshaft was so un-evenly worn that it NEEDED to see a machine shop to be re-useable...... It is a quick and cheap procedure that will save you a lot of time in the end.

 

[sutor623]

Re: Johnson 15 - scored piston and delaminating crankcase

If I were you I would strongly consider this route.......http://www.ebay.com/itm/Johnson-Evinrude-OMC-Powerhead-9-9-15-hp-/290636668048?pt=Boat_Parts_Accessories_Gear&vxp=mtr&hash=item43ab4b9c90

 

[raczekp1]

Re: Johnson 15 - scored piston and delaminating crankcase

its a 1974-1977 powerhead wits some signs of overheating.
this red colors comes when block absorb to much hot from not properly cooled motor

 

[sutor623]

Re: Johnson 15 - scored piston and delaminating crankcase

its a 1974-1977 powerhead wits some signs of overheating.
this red colors comes when block absorb to much hot from not properly cooled motor

I wasnt saying to buy that particular powerhead, just maybe trying to find a powerhead at a decent price off Ebay. But yes, that powerhead itself looks like it got hot as hell!!