1977 Johnson 25hp Lower Unit Removal Issue

reaper2332

Cadet
Joined
Oct 31, 2013
Messages
8
Just want to start by saying, I have looked for an answer to this, but haven't found one.

Question - I am trying to remove the lower unit to access the water pump. I remove the 4 screws from under the side, the nut on the backside, and the screw holding the shifter. I can't get the lower unit to release from the body. Am I missing some other screws, if not then does anyone have any idea on how to get this thing off?

Thanks for the help!
 

milliesdad

Petty Officer 2nd Class
Joined
Dec 20, 2010
Messages
168
Re: 1977 Johnson 25hp Lower Unit Removal Issue

did you take out the screw on the shift linkage or just loosen it?

you have to remove it. the shift shaft has a ball end and the lower end has to come out of the connector
 

reaper2332

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Oct 31, 2013
Messages
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Re: 1977 Johnson 25hp Lower Unit Removal Issue

I tried both, its almost like the back part of the lower unit is stuck or something.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: 1977 Johnson 25hp Lower Unit Removal Issue

Does it move at all? If you have removed everything you said, it should come on off. Perhaps you are being too gentle, or perhaps the drive shaft is rusted in the crankshaft (big trouble). If that is the case, it will come down a bit and then stop like it is hitting a brick wall. About all you can do then is go ahead and force it off, then deal with the frozen shaft later.

OR................

The stud that you removed the nut from may be corroded in the hole that it goes up through. The engineers never learn. Any of us old salt-water outboard mechanics would know better.

Note: While on the subject, those shafts rust and seize because the last guy didn't put a (preferably new) o-ring in the groove at the top end of the drive shaft, and grease the splines.
 

reaper2332

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Oct 31, 2013
Messages
8
Re: 1977 Johnson 25hp Lower Unit Removal Issue

It moves a little bit in the front if I try to pry it off, the back doesn't move at all. I tried putting the nut on the back flush and beating on it with a hammer, still didn't move. I think this is my issue. Anyone know how I can get it off without breaking something.
 

kbait

Commander
Joined
Nov 13, 2007
Messages
2,446
Re: 1977 Johnson 25hp Lower Unit Removal Issue

Spray some penetrating oil (I use pb blaster) around the stud and try it. You can try some heat on the metal around the stud.. hopefully expanding that material so it'll let loose of the stud. Bang on the nut like you have been after heating (not too hard).. go easy on the heat.

Good luck!
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: 1977 Johnson 25hp Lower Unit Removal Issue

Heat is the way to go. The hotter the better. Just short of melting the aluminum is best. Beating on the nut is counter-productive. The mass of the gearcase keeps it from moving in response to the hammer blows. All that does is beat the stud up. Has it been used in salt water?

I ground a chisel to a very thin profile, like a knife blade. Once the area is hot enough, drive the chisel in the parting line, close as possible to the stud, to wedge it apart. Does it bugger it up? Hey, you gotta do what you gotta do.
 

reaper2332

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Joined
Oct 31, 2013
Messages
8
Re: 1977 Johnson 25hp Lower Unit Removal Issue

I will give pb blaster a try, if I cant get it off with that then ill take it to a pro.
 
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