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1949 Johnson Sea-Horse. Half unseized?

C

Colezay

Regular Contributor
Hi everyone, I have a 1949 Johnson TD 20 that I received seized. I put marvel mystery oil in the cylinders and I got it to un seize. Although, it’s still to stiff to spin the flywheel by hand and I can only spin it over using a wrench. The marvel mystery oil has only been in there for a couple of hours. Does it need to soak in marvel mystery oil for longer or is it something else? Also, when I’m turning it over it’ll get harder to turn over for like half a revolution of the flywheel and there is a grinding sound. Is this just crud on the cylinder wall? I’m trying to un seize this engine without having to strip it down as well.
 
Also, how do you take the spark plugs off the wire? This engine has very odd spark plugs.It has a loop which is screwed onto the spark plug wire and that loop goes onto like this barrel on the spark plug with slots in it for the loop to sit.B09B004F-56E9-4852-BA32-02FC84039443.jpeg I spilt “some” marvel mystery oil hence the oil covered cylinder head.
 
I couldn’t see any nut that I’m aware of. I am aware the end of a sparkplug can come off but it’s stuck on there. I can take the screw off the spark plug wire but then I’m still in the same situation. What I’ll probably do in the future is just put that loop on a sparkplug and crimp it on there. The engine has spark surprisingly enough. Also the old owner was able to get one off... I don’t know how he did that:confused:
 
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There is threads under that sleeve (nut), that is holding the wire clamp down. It should come loose with a pliers but soak it a little bit too. You should also look in the area behind the carburetor and see if water got past the reeds and into the crankcase causing rust. You will likely have to dismantle and clean the carburetor anyway. The greatest rust blaster I have found is a 50/50 mixture of acetone and automatic transmission fluid.
 
??----Remove the recoil.-----Remove lower cowling.--Remove gas adjustment.----Remove tank.------Have not worked on one in a while.----Have a couple of these motors kicking around in my cluttered shed.
 
I got it off. Top cylinder sparks bottom doesn’t. From what I can see without taking the flywheel off the coils look fine. Most likely just the points. Engine still isn’t spinning 100% freely, although I can spin it by hand now. Once it gets running it should free up completely, right?
 
Yes, sorry, I never bothered to note your model number. They work like most chainsaws.....no reeds. Nice engineering too. My shed is more than cluttered, it's deplorable.
 
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