Hi, I would like to get some experienced opinions on what kind of mimimum repair I can get away with to get my ole Evinrude running again. The motor has been in my family since new and so far has been good to us. It has seen about 4 years of storage until last summer when I decided to get her running again, but had a problem where it would not get up on plane. I put new carb kits in after thorough disassembly and cleaning in acetone, replaced all rubber fuel lines in motor, new remote gas tank, and replaced the VRO with a standard ole fuel pump and premix the gas. Also, prior to last outing, I put an older (79??) lower gearcase on with a rebuilt water pump, and pee-hole flow was strong
Ran great this summer initially, but started getting finicky at idle sometimes where it wanted to stall. Finally, over the past weekend, it decided to make a big backfire as I dropped off throttle after a high speed run and it died. It would run with the fast idle lever maxed out but sounded pretty nasty. Engine block was not hot, actually kind of cool which surprised me. Finished off the day on the lake putting around and fishing with the old trusty 15hp evinrude kicker.
Back at home, a compression check showed 45 psi on the top cylinder, with 102 and 110 on the others. I pulled the head off tonight and found what looks like the results of a fragmented piston ring. What I could see of the cylinder walls looked surprisingly good, just one area of a slight scape where there is damage to the piston edge and the top of a transfer port.
I have never encountered something like this before, but am not hesitant about learning what I need to to fix this myself as much as I can. I have an 86 Johnson parts motor that has a blown top end I picked up for the lower gearcase, and hoping it has a good head that I can use.
What do you all think is needed to fix this? I'm thinking new piston and rings, and hone the cylinder bore........given that I don't find anything bad in the crankshaft area. Some of the concerns I have is whether the slight scuffing on the cyl walls is too much, whether the small damage to the upper end of the transfer port will cause problems, and if the resulting compression of a repair would be too high relative to the two other cylinders. Also, are the rings on the other cylinders ready to fail soon as well?
Other questions:
(1) based on the picture of a fragment, is this a busted ring? wedge shaped piece?
(2) cause of damage? doesn't look like a lean condition or lack of oil or overheat.
(3) location of other fragments - do I need to tear down the exhaust pathways to clean out?
(4) other things I've missed?
Well, here are the pics -
Ran great this summer initially, but started getting finicky at idle sometimes where it wanted to stall. Finally, over the past weekend, it decided to make a big backfire as I dropped off throttle after a high speed run and it died. It would run with the fast idle lever maxed out but sounded pretty nasty. Engine block was not hot, actually kind of cool which surprised me. Finished off the day on the lake putting around and fishing with the old trusty 15hp evinrude kicker.
Back at home, a compression check showed 45 psi on the top cylinder, with 102 and 110 on the others. I pulled the head off tonight and found what looks like the results of a fragmented piston ring. What I could see of the cylinder walls looked surprisingly good, just one area of a slight scape where there is damage to the piston edge and the top of a transfer port.
I have never encountered something like this before, but am not hesitant about learning what I need to to fix this myself as much as I can. I have an 86 Johnson parts motor that has a blown top end I picked up for the lower gearcase, and hoping it has a good head that I can use.
What do you all think is needed to fix this? I'm thinking new piston and rings, and hone the cylinder bore........given that I don't find anything bad in the crankshaft area. Some of the concerns I have is whether the slight scuffing on the cyl walls is too much, whether the small damage to the upper end of the transfer port will cause problems, and if the resulting compression of a repair would be too high relative to the two other cylinders. Also, are the rings on the other cylinders ready to fail soon as well?
Other questions:
(1) based on the picture of a fragment, is this a busted ring? wedge shaped piece?
(2) cause of damage? doesn't look like a lean condition or lack of oil or overheat.
(3) location of other fragments - do I need to tear down the exhaust pathways to clean out?
(4) other things I've missed?
Well, here are the pics -
