compression on 57 johnson 35hp

[chattyrona]

We are still trying to get this old Johnson 1957 35hp seahorse started and after doing a compression test, one cylinder reads 90 and the other reads about 110 is this significant and what next? Thanks in advance.

 

[samo_ott]

Re: compression on 57 johnson 35hp

They are a tad far apart. It's recommended that they be within 10% of each other. If it was me, I would change the head gasket and do a decarb and then test it again to see what I got.

I just reread your post. If you are just trying to get it started, it should not make a diff. That's plenty of compression to start it. If it is not starting look at fuel or spark. Does it have new coils and/or a good 1/4" blue spark? Have you tried spraying 24:1 pre mix in the carb?

If it still does not run, read "Awakening an Outboard" previously posted on this forum. You'll need to search for it.

 

[JB]

Re: compression on 57 johnson 35hp

Go to "Outboard won't start" in the Engine FAQs.

 

[spy1309]

Re: compression on 57 johnson 35hp

My 1960 Johnson 40hp is similar with yours , the compression I have is 90 and 100 Psi it starts at first cranks so you should have no problems starting it.