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Advice on 1969 Evinrude 4Hp

S

Snapper Fisho

Regular Contributor
Hi all, I picked up a 4hp lightwin in great condition for its age without doing a compression test or running it before buying (got deceived by the look of this and got the better of me).
Anyway, to my surprise bot the cylinders showed 45-50max psi and my gauge is good. I used both standard hose and the smaller push in which gave me 50psi. Was surprised and struggled to get it going but eventually did at higher throttle. It runs, the head gets quite hot and then dies. I pulled off the leg and checked water pump, all is good and did a carby service too.

So, I pulled head off hoping I have a blown head gasket but seems maybe I am unlucky and rings are the problem? Didn't take exhaust cover off to check them through the post holes. There is a little bit of play when I move the pistons and some light scoring of cylinder walls but not grooved. I have attached pics if anyone has any suggestions. Could it still be a head gasket issue and not rings as wasn't expecting such poor comp readings?


Pistons 1.jpgCylinder 2.jpgInside Head.jpgInside Head-cleaned.jpgCylinder 1.jpg
 
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Thanks racerone. Glad to be guided by you with your knowledge and experience. I read about Seafoam comments from others in US but wasn't sure as it's not as readily available here in Aus. Cheers
 
I suspected so and will give it a go, as this little vintage outboard is in such a great state otherwise. Appreciate your help racerone.

When I managed to start it with the throttle lever advanced and then it died as I tried to keep it running at reduced throttle, I noticed the carb throat started discharging some smoke. Never seen that before.
 
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???----The reed valves prevent anything like exhaust from coming out of the carburetor.----The motor needs to come apart.----End of the story.
 
I totally agree with RacerOne, disassemble to assess the damage. It is possible that there may be a chipped reed causing the smoke coming out of the carburetor. Please let us know what you find.
 
Thanks again guys. It threw me totally when I saw that. Got it to finally run and then saw that as it started to want to cut out and that's when I noticed the top of the head being quite hot. Took leg off again and double checked the copper tubing by attaching hose to it and there was no water restriction.

Thought maybe stuck piston rings could be that but I don't have the experience of racerone and others here.
 
fdrgator said:
The hot head is normal. Only the edges of the head are water cooled. The rest of it has fire inside.
Click to expand...

That helps fdrgator as apart from low comps it is a very clean motor for it's 52 year age.
My comp tester is fine too as it gives 100psi for the 1988 15hp I have.
 
I won't argue about the compression, but I sort of doubt it only has 45 psi. It's running. Something is wrong there.
 
My comp gauge is an ABW Master one so decent quality but having said that it tends to give 10psi lower readings than some other gauges. I noted that at a mechanic shop a while back as his put my 1982 115hp at 116ps on one cylinder as an example, whereas mine gave 106psi on same day, same testing conditions at WOT.
I retested this 4hp lightwin after running it and best readings were 50psi with the push in adapter in the kit also.
 
I managed to get a head gasket and thought to replace it as a last resort, in the hope that it may improve my low comps and hard starting. Well as I tried to pull start it to get comp readings, my starter recoil gave way and I thought it was the spring. I pulled it apart and to my surprise the lip on the other side of the starter rope pulley that locks into the spring broke off, as pictured. :(
Has anyone seen that happen? I think I lucked out on this little vintage Broken starter pulley spring lip.jpgoutboard.
 
Snapper Fisho said:
I managed to get a head gasket and thought to replace it as a last resort, in the hope that it may improve my low comps and hard starting. Well as I tried to pull start it to get comp readings, my starter recoil gave way and I thought it was the spring. I pulled it apart and to my surprise the lip on the other side of the starter rope pulley that locks into the spring broke off, as pictured. :(
Has anyone seen that happen? I think I lucked out on this little vintage View attachment 27550outboard.
Click to expand...

You should be able to find one of those without issue.
 
When you took the head off, did you check it for “flatness”? Lay a steel straightedge across, slip a feeler gauge in & see how much it’s warped.
I picked up an 8hp with low compression. Head was warped .005”. Decked it flat with wet/dry on a sheet of glass, then reinstalled the head. Compression came up to 110psi. Don’t just use up a new gasket without decking the head.
Racer now has it to put together properly.
 
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Edchris177 said:
When you took the head off, did you check it for “flatness”? Lay a steel straightedge across, slip a feeler gauge in & see how much it’s warped.
I picked up an 8hp with low compression. Head was warped .005”. Decked it flat with wet/dry on a sheet of glass, then reinstalled the head. Compression came up to 110psi. Don’t just use up a new gasket without decking the head.
Racer now has it to put together properly.
Click to expand...

Thank you too for your input Edchris177. I laid the head on glass also and there was no movement. Seemed straight to me so I thought a new head gasket would improve it a bit but 45-50psi readings beforehand and very hard to start made me think a ring issue like racerone was saying.
 
Well I have an update everyone now that I have a working side rope starter again. After replacing head gasket my compressions improved a bit to 55psi. I took flywheel off and tested both coils, leads with multimeter and all good. Make a very minor adjustment to the point for the bottom cylinder as it wasn't as snug as the top with my 0.020" feeler gauge. Ran a point file through both contacts also. Spark jumped a 1/4 inch gap on both cylinders. Started on my 4th attempt and got it to run a while at a fast idle, then increased throttle again and then to full. Seemed to come to life and showed top end power that I never saw before. Even head did not smoke or feel as very hot as before. Here is a video of it running. Could it be that the piston rings have unstuck to some degree? In any case, she starts and is a runner. Doesn't heat up like it did and stays running, so I'm quite pleased! :)

https://drive.google.com/file/d/1wwhK4k92mdZtVMpyV0vkMUu9PgwIa7EE/view?usp=sharing
 
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