Hello. Ran into an issue with my 1979 Evinrude 115 outboard the other day. I will do my best to explain the issue as well as the troubleshooting outputs thus far. I am looking for additional guidance on what I should check before breaking into the engine internals.
Sorry for the long explanation....
Here is background info as well as the issue:
The engine never had issues for 7 years of my ownership. I conducted most of the maintenance as well as winterization every winter. Last summer, the boat sat as I was deployed over the summer. This summer, after taking the boat out of winterization, it had a slight issue with idling as it seemed to sputter, but still ran, and ran great at WOT. i figured that I was still burning through the old, stabilized gas. I was going to get the carbs repaired at the end of this season knowing that it had an idle issue. But that isn’t the big issue. Out on the lake the other morning cruising at WOT, the engine suddenly lost power and stalled out. I sat there for a minute, and turned it over again. Started right up but now the motor ran fairly "bumpy" and rough, but still sputtered at idle (this time more than the previous slight sputter). I then tried to bring it up slowly to WOT but stalled again when close to WOT. I was able to quickly turn it over again, but this time i slowly made my way back to dock at the slow, sputtery idle. When I put it into neutral at the dock, it cut out on me. I packed it up that day and started combing the forums for some help.
I heard various things about "simple" fixes like ensuring no cracks in the fuel line, bad fuel pump, carb cleaning to “advanced” fixes like new head gasket, cylinder repair, rings and pistons.
So I took the advice from this forum on running a few tests first….
1. I checked to ensure that the overheat sensor/alarm was working. Note that I did not hear one at the time of my issues out on the lake. I grounded the temp sensors earlier today and heard the alarm sound. OK those work. Assume that I did not have an overheating/thermostat problem. Correct?
2. Compression test (followed JB’s instructions). 1 cylinder (starboard top) at 120psi, 2 cylinder (port top) at 115 psi, 3 cylinder (starboard bottom) at 70 psi, and 4 cylinder (port bottom) at 118 psi.
So it looks like the issue can lie in the 3 cylinder.
My question is, what should I do next? I read and heard different courses of action. I heard to rebuild the carbs (I should probably do this any way since I never cleaned/repaired them in my 7 years of ownership…. Not sure about other previous owners) as maybe one of the cylinders is not getting fuel to seal the rings. I have also noticed some fuel dripping from the base of the air silencer box and its drain hose…. Maybe the float valve is not closing anymore.
I have also heard that I need to remove the starboard side head to inspect the #3 wall and piston for damage. Is it simple to remove the head to inspect? Can the head slide off and on easily enough without damaging anything further? Do I need to ensure the pistons are in a certain location to remove the starboard side head?
I heard a simple check to see if it’s not a piston/ring issue (but a fuel issue) is to put gas/oil into the cylinder and run the compression test again. If the compression goes up, its fuel starvation from a bad carb. True?
I appreciate any help and guidance. Based on my course of action, I will probably have additional questions to follow up with.
Thanks for the help!!!!!
Sorry for the long explanation....
Here is background info as well as the issue:
The engine never had issues for 7 years of my ownership. I conducted most of the maintenance as well as winterization every winter. Last summer, the boat sat as I was deployed over the summer. This summer, after taking the boat out of winterization, it had a slight issue with idling as it seemed to sputter, but still ran, and ran great at WOT. i figured that I was still burning through the old, stabilized gas. I was going to get the carbs repaired at the end of this season knowing that it had an idle issue. But that isn’t the big issue. Out on the lake the other morning cruising at WOT, the engine suddenly lost power and stalled out. I sat there for a minute, and turned it over again. Started right up but now the motor ran fairly "bumpy" and rough, but still sputtered at idle (this time more than the previous slight sputter). I then tried to bring it up slowly to WOT but stalled again when close to WOT. I was able to quickly turn it over again, but this time i slowly made my way back to dock at the slow, sputtery idle. When I put it into neutral at the dock, it cut out on me. I packed it up that day and started combing the forums for some help.
I heard various things about "simple" fixes like ensuring no cracks in the fuel line, bad fuel pump, carb cleaning to “advanced” fixes like new head gasket, cylinder repair, rings and pistons.
So I took the advice from this forum on running a few tests first….
1. I checked to ensure that the overheat sensor/alarm was working. Note that I did not hear one at the time of my issues out on the lake. I grounded the temp sensors earlier today and heard the alarm sound. OK those work. Assume that I did not have an overheating/thermostat problem. Correct?
2. Compression test (followed JB’s instructions). 1 cylinder (starboard top) at 120psi, 2 cylinder (port top) at 115 psi, 3 cylinder (starboard bottom) at 70 psi, and 4 cylinder (port bottom) at 118 psi.
So it looks like the issue can lie in the 3 cylinder.
My question is, what should I do next? I read and heard different courses of action. I heard to rebuild the carbs (I should probably do this any way since I never cleaned/repaired them in my 7 years of ownership…. Not sure about other previous owners) as maybe one of the cylinders is not getting fuel to seal the rings. I have also noticed some fuel dripping from the base of the air silencer box and its drain hose…. Maybe the float valve is not closing anymore.
I have also heard that I need to remove the starboard side head to inspect the #3 wall and piston for damage. Is it simple to remove the head to inspect? Can the head slide off and on easily enough without damaging anything further? Do I need to ensure the pistons are in a certain location to remove the starboard side head?
I heard a simple check to see if it’s not a piston/ring issue (but a fuel issue) is to put gas/oil into the cylinder and run the compression test again. If the compression goes up, its fuel starvation from a bad carb. True?
I appreciate any help and guidance. Based on my course of action, I will probably have additional questions to follow up with.
Thanks for the help!!!!!
