Locked Johnson Motor

[msf171]

I have a Johnson 25 hp motor, I think about a mid-70's model, that has locked-up. I have disassembled it down to the power head, and would appreciate any suggestions on the best way to separate the crankcase halves without causing damage to the aluminum case.<br /><br />Thanks!<br />Mark

 

[adrian bick]

Re: Locked Johnson Motor

It should come apart easily. You MUST remove the reed valve plate to access 2 screws.

 

[Fouled Plug]

Re: Locked Johnson Motor

Did it lock up to overheat/no oil, or just sitting? I have an Evinrude 6 that sat for several years and wouldn't turn over. I pulled the cylinder head and soaked the piston tops/rings for a couple days in WD-40. I then took a block of soft wood and a hammer and tapped on the pistons (this won't work if the piston is at TDC) gently and patiently until they began to budge. More WD-40, more tapping, until they were free. Result? 102# on top and 95# on the bottom. Definately not optimal, but for a motor that was given to me it's fine! <br /><br />------------------<br />I'm going to invent a TCW3/citronella oil blend and make a fortune!

 

[hondon]

Re: Locked Johnson Motor

Should come apart easy with a few light taps with a soft mallet on the crank .Did you remember the alignment pins?

 

[Walter]

Re: Locked Johnson Motor

I was 9 years old when my dad gave me my grandfather's 1941 Johnson TD-20. It was locked up tighter than Levenworth, so I took it up to my uncle who did almost exactly what Fouled Plug describes...only he soaked it with #2 diesel fuel. Two days later it was running and still is. Give it a shot....<br /><br />Walt

 

[msf171]

Re: Locked Johnson Motor

Thanks for everyones help, I was able to get the motor free by tapping the pistons as recommended. The more WD-40 I sprayed on the top crankcase bearing, the easier it is to turn, think my problem is there and hope to be able to get the motor apart where I can replace it.<br /><br />Thanks Again!<br />Mark