1969 Johnson 20 seized

[BROUSSARD2]

Just got a 1969 Johnson 20 HP. The top cylinder is seized and the flywheel will not budge at all. Ive tried JB Blaster in the cylinder, WD40, and have not taken the head off and put in Mystery Oil. It sat overnight, the bottom cylinder drained on through but the top stayed, maybe drained just a bit. Any suggestions on things to try to fix this? Is it work the effort to take this apart to repair? Ive watched several Youtube videos, but to no avail. Thanks for any recommendations.

 

[Scott Danforth]

depends on where you are, that motor would be about $75-100 in running condition. if the cylinders are scored, pistons, machining, gaskets, bearings, etc. will run you more than the motor is worth.

 

[so]

my single cylinder 2 hp was seized also. I soaked it in 50/50 mixture of ATF/paint thinner for 3 days, it finally broken loose.

 

[flyingscott]

Have you tried taking the lower unit off.

 

[boobie]

Pull the cylinder head and see what you have.

 

[Crosbyman]

yep pull the cyl head ... oil it and poke it with a mallet and a 1 inch wood peg to jar it a bit

mark the flywheel position with a felt pen and look for small movements

takes time and patience ...oil poke oil poke oil poke alternating the cylinders

got my 9622a back to life that way

 

[merkdawg0084]

yes, take the head off and turn the motor upside down where the pistons are level. not like the motor is on the back of a boat. I just did this with a 7.5 over the weekend. fill head with pb blaster or ATF. Hell i actually put a bit of coca cola in there. Let it sit for a few days. If it's just a bit of surface rust,I used a blue scotch brite pad. Nothing too abrasive and i lightly scrubbed the cylinder walls when they were wet to break up some of the rust.Then i did what crosbyman said to do. Now if you have one cylinder that has more rust than the other, make sure you push that piston down first and not up. That way it won't score the walls of the cylinder and you have easier access to the rust on that wall.