1976 Johnson 15 HP lower unit seals and impeller

[Seahorse16]

When I got this motor last fall I drained the lower unit oil and got a nice milky water surprise, so I knew I likely needed to replaced the lower unit seals. I also noticed dark black oil coming from around the prop. Still, I replaced the lower unit oil and took it for a test drive, and then I also ran it in a barrel.

In order to make an attempt at changing the seals I drained the lower unit oil again, and was surprised to find it clear of any water. However, after leaving my lower unit in a barrel for a week the water turned black (on the surface) from black oil leaking out from prop. Attached are pictures from inside the lower unit with prop removed. I'm not that familiar with the plumbing setup. It this just residual oil from the exhaust coming out prop? Or is this another seal somewhere I need to fix?

I saw a youtube post of a guy drilling into the seals, then putting in screws and pulling the seals out. Is this something worth trying? The tried to pressure test the lower unit, but my brand new compressor died (need to take it back tomorrow). I figured I would replace them anyway since I dropped the lower unit.

Also, how do you know when impeller needs replacing (picture attached)? I will probably do it regardless since it's pulled, but just curious.

Sorry, I know that was a boat full of questions, but I appreciate all help or suggestions!

Trevor

 

[175se]

Re: 1976 Johnson 15 HP lower unit seals and impeller

the oil coming out the prop(black nasty) is from the exhaust, smell it -it will smell like fuel.-as for the impeller you have it down why not, its cheep insurance. the deal with the screws I don't know,ive got the proper tools so I do it that way- even if they come out they still have to go back in. If you pressure test it you also want to do a vacuum test also,only use 6or7 lbs, .

 

[Seahorse16]

Re: 1976 Johnson 15 HP lower unit seals and impeller

So it's a coagulated thick black oil. I agree that is it likely exhaust residual, perhaps accumulated from sitting for years and then finally leaking out. So, I assume this is "ok", right? As long as the seals at the prop and below the impeller are sealed is that all i need to worry about from that regard? I also ordered an O-ring that must go inside near the gearcase. I can't get at that without pulling everything out. Does this need to be replaced too?

As far as the proper tools, what are they? They mention nothing of the tools in any of the books I have or shop manual.

Thanks!

 

[175se]

Re: 1976 Johnson 15 HP lower unit seals and impeller

the tools are basicly a seal puller- and a seal installer,local auto pts store--the o-ring goes on the front of the bearing carrier yes you would have to pull that out, but wait till you do press & vac test to see if you have to.

 

[boobie]

Re: 1976 Johnson 15 HP lower unit seals and impeller

To do a pressure or vacuum test use 6-7 to start out. Then go to 12-14. This is both PSI and Hg.

 

[racerone]

Re: 1976 Johnson 15 HP lower unit seals and impeller

Do not forget the o-ring where the shift rod goes into the housing.

 

[Seahorse16]

Re: 1976 Johnson 15 HP lower unit seals and impeller

Ok, so I got both the upper and driveshaft seals replaced and replaced the impeller, but now I can't get lower unit back on. To take off the lower unit, I simply removed the 6 bolts holding it together (3 on each side), this dropped the lower unit 3/4 inch, which allowed access to a screw that held the shift cable in place. Once I removed this screw the entire LU came off.

In trying to get it back on, I got the shift cable back into the metal clip and attached the screw, but now the LU will not rise the last 3/4 inch. Any ideas??? The driveshaft is as low as it can go. If I spin the prop, the driveshaft moves, so it must be lined up, right? Do I just need to keep playing with it? HELP

Thanks!

 

[Seahorse16]

Re: 1976 Johnson 15 HP lower unit seals and impeller

Nevermind. I found a thread that talked about moving the flywheel to get it lined up. It worked!