Johnson 1975 25HP, 25R75B, Heavy Smoke and Oil seeping out of every orifice?

btkees

Cadet
Joined
Dec 19, 2012
Messages
11
I have a new to me Johnson 1975 25HP, 25R75B. I am unfamiliar with these older engines. So I come to you experts for guidance. History of the engine. The engine looks immaculate... however... the engine sat in at shop after work completed, tune up. Maybe a year or so, shop owner was unable to get in touch with past owner did not pay and moved away who knows. I paid the bill plus very little, and there loss became my gain and another headache. So here's my potential problem, it fires up idles kind of rough. I cleaned carb out, idles better. The lower seeps a good amount of gunk/oil out of every orifice leaving a good top layer in the drum after running. Eventually after a few minutes of running it stalls. Ill leave it there for your much appreciated guidance. Thanks in advance for all your input.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Well the gunk in the barrel is somewhat normal. But it might be more than normal, since it is not running properly. So don't worry about that right now, just concentrate on getting it running right. The gunk will take care of itself when you get it running right, then out of that barrel and on a boat on the lake where it was designed to run.
 

btkees

Cadet
Joined
Dec 19, 2012
Messages
11
Roger that. Thanks for the reply. This is only the second outboard owned and worked on and not have seen that much gunk and oil seeping from every lower orifice.
 

w2much

Lieutenant
Joined
Jun 22, 2005
Messages
1,276
Check and double check that it is running on both cylinders. It will start and run on one which may deceive you. I am having the same issue on one of mine.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
Messages
47,297
the gunk in the barrel is exhaust residue, and oil and fuel from the cylinder that is not running.

you have come to the right place to get your outboard running both F_R and racerone know their stuff
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Make sure it is running on both cylinders( cyl drop test) and then take it out on the lake and run the heck out of it.
 

Sirrobin53

Petty Officer 2nd Class
Joined
Mar 13, 2012
Messages
189
All the information so far is accurate. May I suggest another one?
Are the fuel line connections at tank and motor sound? Alcohol fuel eats the O rings pretty fast on the older motors causing a lean condition. Sometimes i get less than a year on mine. I run those old motors and have had more than one of em fool me with that simple failure. It's a simple fix as well. Non alcohol fuel is your friend.
 
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