1972 Johnson need help

jmac

Cadet
Joined
Apr 3, 2002
Messages
8
Hey Guys and Gals Haven't posted much ever but have read alot from ya'll and have learned quite a bit. But now I have a problem and need a hand.<br />I have a 25 hp 1972 Johnson. I've maintained it and kept it running fairly well until the other day. Was out fishing and on the return trip it started running real bad at anything over half throttle. It sounded and felt like it had a bad miss. So bad I was just glad to get home. So I changed plugs, cleaned carb etc. and took it out today. Nothing changed. It starts 2-3 pulls and idles and runs fine till you go to open it up. Anyway, had the cowling off and was adjusting the carb, thinking that may be it, when I noticed frothy liquid(Fuel?), coming out the seam where the two halves of the crankcase meet. I think this is causing a vaccum leak, the source of the problem. Could this be it? Is there a gasket that goes there or is it a machined fit? What could have caused this? How to fix and how hard? I got this motor from my dad and I'm pretty sure that the points, coils, wires have never been looked at. I'm fairly mechanically inclined. anyway any advice, comments, suggestions would be appreciated. Didn't mean to be so long winded but wanted to give ya'll a detailed description.
 

S.T. Marine

Petty Officer 1st Class
Joined
Aug 13, 2002
Messages
248
Re: 1972 Johnson need help

My 1976 johnson 25 leaked gas from the crankcase too. It happens with age. You have to take off the powerhead and split the block. Clean the surface and put perfect seal on both halfs and put it back together. That will fix it. Nothing lasts forever. Its straight forward project
 
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