'78 Evinrude with Loss of Power/ Overheating

[chad102]

I recently replaced the impeller on my '78 Evinrude 55hp ( thanks to some helpful tips here). I took it out for a run yesterday and it ran great for about ten minutes, then the engine lost some rpms and dropped my speed about 5 mph, while staying at full throttle. I cut the engine off for a few minutes, then started her up again, and this time I could only get about half of my normal power at full throttle, and the engine sounded rough. The alarm also went off a few minutes later. I managed to get back to the boat launch, but I don't know why my engine is acting up. I had constant water flow through the engine while it ran, and I nver had any indications of overheating or power problems while testing the engine at home. Any suggestions? Thanks!

 

[R.Johnson]

Re: '78 Evinrude with Loss of Power/ Overheating

At this point I am at a loss as to why the horn was this late in going off. If the engine was so hot as to be losing power, you should of had a horn before then. One thing is you could have had a bad sensor, or one corroded, and the corrosion acting as an insulator. At this point I would start with a compression test, then check the fuel, and ignition system. If you feel the engine lost power from an over-heat, it would not be a bad idea to pull the cylinder head to have a look at the cylinder walls.

 

[Bass Runner]

Re: '78 Evinrude with Loss of Power/ Overheating

what oil mix you using in the motor sounds like lack of oil or water one unless it is way out of time.

 

[chad102]

Re: '78 Evinrude with Loss of Power/ Overheating

R. Johnson and Bass Runner, Thanks for your tips. I have recently cleaned all of my connections and exposed connections when I installed a new solenoid; I thought I had cleaned all of the exposed connections, but I did notice some corrosion. If I am able out look at the cylinder walls, what should I look for?<br /><br />Bass Runner, I have always used a 50:1 oil mixture, but I have never experienced this problem before. <br /><br />Am I wrong in thinking that there is sufficent water flow if the water is coming out of the top spout, and that the water pump is working correctly?