Pontoon Boat & Deck Boat Forum

I went outside last night to drain the oil in my gear case of my 1981 115hp Johnson 2 stroke. I have only owned this boat for about 6 months. I noticed oil leaking onto the propeller and a lot of oil on the fin on the bottom. I also noticed oil where the gear case connects to the motor. I drained the oil and found no water in the oil. Do I need to replace the seals on the gear casing? How hard is that to do?

tucker0104 wrote:I went outside last night to drain the oil in my gear case of my 1981 115hp Johnson 2 stroke. I have only owned this boat for about 6 months. I noticed oil leaking onto the propeller and a lot of oil on the fin on the bottom. I also noticed oil where the gear case connects to the motor. I drained the oil and found no water in the oil. Do I need to replace the seals on the gear casing? How hard is that to do?

Replace seals? I would say yeah. How hard to do it? I have not had to do that but I am the kind of person who would try. I may get flamed on this comment but that engine is one old work horse so even if you work on it and find yourself in the weeds, you will learn what you can and can't do. So either you repower or cruise this year knowing how to those repairs. My desire to learn (f it up) is greater than the $150/hr the marina would charge initially.

You may also get to add some cool new tools to the box.

If their is no water in he LU oil then it will be unburnt 2 stroke oil from the exhaust, that's common and it fine.. Now changing the LU seals can be very easy or hard depending on the motor. IF you think it may be a problem run a vacuum / pressure test that removes any doubt or tells you it needs seals. I test mine ever fall when i pull it for the winter, if it fails then i have time to fix it.

Everyone needs to have a pressure/vacuum test on any used outboard or inboard outboard boat they're purchasing. The seal kit may be something like $80, and it's about $200 to have them installed. You can see some illustrations on UTube on how to get out the old seals and put the new ones in. It can be a little frustrating.

And it doesn't hurt to have your lower unit inspected every 3 years or so, depending on amount of use.

Sounds doable.

MH Hawker wrote:If their is no water in he LU oil then it will be unburnt 2 stroke oil from the exhaust, that's common and it fine.. Now changing the LU seals can be very easy or hard depending on the motor. IF you think it may be a problem run a vacuum / pressure test that removes any doubt or tells you it needs seals. I test mine ever fall when i pull it for the winter, if it fails then i have time to fix it.

This. Probably just 2 stroke oil.

tucker0104 wrote:I went outside last night to drain the oil in my gear case of my 1981 115hp Johnson 2 stroke. I have only owned this boat for about 6 months. I noticed oil leaking onto the propeller and a lot of oil on the fin on the bottom. I also noticed oil where the gear case connects to the motor. I drained the oil and found no water in the oil. Do I need to replace the seals on the gear casing? How hard is that to do?

I agree with two other answers here. Fuel and oil dripping down. Disconnect your fuel line when not in use and see if it stops.

Older 2 strokes often drip oil, if it's not gear oil it's nothing to worry about. Being that you had clean gear oil supports this. My 115 Evinrude (many boats ago) would drip oil out of the exhaust unless it was winterized and the fuel drained.