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59 evinrude 10 hp

P

poppaed

Member
Two questions: 1. what is compression specs on this motor? Why will the engine dry start at home but won't start in the water at the lake and sometimes starts fine after warm up, sometimes not.
 
Evinrude did not publish compression specs. Not knowing them, I'd expect around 85 psi or so. As for the cause of your problem, the compression would be first thing to check. Then the ignition system. Have you checked the coils? I'll guarantee they are NG unless they have already been replaced.
 
I have all new points, condenser, coils, and plugs. Only readings I could get were when the engine was cold. They were about 15 and 27 since the gauge don't one or five marks. It when from 0 to 30.
 
Pull the head and inspect the cylinder walls. You can also pull the exhaust cover on the side. Carefully push on the rings if they are still springy and there is no scoring on the cylinders get new gaskets and put it back together. Lightly surface the head on a glass table with 220 grit swirl in a figure 8 pattern. pull the head down slow in at least three steps to the proper torque 120 inch lbs. Use your lawn mower to test the compression tester. Check the compression engine cold and test each cylinder three times 1-2 1-2 1-2 that accounts for any mistests. Use the high number for each cylinder.
 
<30 psi compression is no compression. The head gasket may be blown between the cylinders. If not, then there is major engine damage. You will see it when you get the head off.
 
I'll take a guess/prediction. Wrist pins have dropped down and worn grooves in the cylinders. Pre-1961 10hp motors are notorious for beating the wrist pins loose in the pistons. When they get bad enough and rattle around loose long enough, they drop down and end of story.

But of course, there is no way to know without inspection.
 
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