Waking up a 1960 Johnson Seahorse 5.5 HP (Model CD-17)

H

hempfarmer

Petty Officer 3rd Class
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Oct 13, 2009
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80
Hi everyone,

I picked up this engine that looks to be in good shape but hasn't been run for 15 years. It has sat outside in a sheltered shed.

Based on what I have read it is best advised that I check the compression before servicing the water pump, changing coils, replacing spark plugs,etc.

Are there any precautions I should take before checking compression? Ex. spray some oil in the cylinders or spray some sea foam in there?

Any advice you can provide is greatly appreciated.

Thanks,
Russ
 
D

Daviet

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Sep 24, 2008
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8,958
Re: Waking up a 1960 Johnson Seahorse 5.5 HP (Model CD-17)

It woun't hurt anything to squirt a little oil in the cylinders, then turn it over slowly by hand to spread the oil around.
You might also check out the "Top Secret File" sticky, at the top of the page, there is a section in there about awakening a sleeping engine.
Lots of good information there.
 
nwcove

nwcove

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Re: Waking up a 1960 Johnson Seahorse 5.5 HP (Model CD-17)

id pull the plugs and slowly rotate the flywheel by hand to feel and listen for any scraping under the flywheel ( rust on coils or magnets), or binding in the cyls. if all is good, give it a shot of wd-40 and test away! nice lil motor!
 
HighTrim

HighTrim

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Re: Waking up a 1960 Johnson Seahorse 5.5 HP (Model CD-17)

As nwcove mentioned, a little wiff of WD40 is ok, but I do not like using oil before a compression test. It should be done cold and dry.

The reason? You want a baseline for future comparisons, AND, adding oil is cheating. The oil will "cure" stuck rings, giving you a false reading. Better to know the truth right?

Adding oil, and testing warm, would cause trouble for future testing as you would never be able to mimick the exact conditions that you tested at. Doing it cold/dry is easy to mimick for comparison.

But if it has been sitting a few years, a little WD40 wont hurt.
 
H

hempfarmer

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Re: Waking up a 1960 Johnson Seahorse 5.5 HP (Model CD-17)

Thanks for all the advice. I purchased some Seafoam Deep Creep and put 2 squirts in each cylinder. Not sure if I should put more but I'll let that sit for a day before doing anything.

Attached is a picture of the plugs. The bottom one is rusted really bad. Anything to be concerned about or is this normal considering how long this thing sat?Plugs.JPG

Thank you!
 
HighTrim

HighTrim

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10,486
Re: Waking up a 1960 Johnson Seahorse 5.5 HP (Model CD-17)

Well I dont think that plug will be reusable :)

Hard to say for sure. Sometimes plugs are thrown in just to plug the hole. Hopefully there was not moisture in the powerhead.

Let us know what you find
 
H

hempfarmer

Petty Officer 3rd Class
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Oct 13, 2009
Messages
80
Re: Waking up a 1960 Johnson Seahorse 5.5 HP (Model CD-17)

I completed a compression test, here are the results:

Top cylinder - 79

Bottom cylinder - 81

I got the top cylinder reading after 3 pulls but it took the bottom cylinder 6 pulls. Is this telling me something?

Also, Attached is a photo of the sparkplug insert that came out when I removed the compression tester. I put it back in for the second test(bottom cylinder). Anyone know what should be done to repair this?

spark plug insert.jpg

Thanks!

Russ
 
H

hempfarmer

Petty Officer 3rd Class
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