Leaking lower unit

dradford78 · Jun 22, 2011

First time posting here but what a great site. I have a 64 Johnson 9.5. Recently acquired this motor and have taken it on the water twice now. Last time I was out I noticed a lot of oil in the water at the dock when I came back. After getting home and looking again there is gear case oil leaking out of a small hole on the lower unit above the level of the fill plug on the mounting side of the motor. I drained the lower unit and there has been water mixing with it and the oil that was drained was the same color as the oil leaking as well as the sewage smell of gear oil. I am planning on removing the lower unit for inspection but before I start I want to make sure I will not break anything. Removal of the lower unit I think requires removal of the power head in order to reach the shift linkage. Secondly any ideas why gear oil would be leaking from this hole.
Thanks everyone

Daviet · Jun 22, 2011

Re: Leaking lower unit

If the leak is above the water pump I beleave what you are seeing is unburnt fuel mixture. It should have a gas smell to it. Water mixed in the lower unit oil should be a brown or tan color.

dradford78 · Jun 22, 2011

Re: Leaking lower unit

The oil that was leaking out of the hole was a tan color and was the same color, consistency and smell of the oil drained from the lower unit. The motor was laid on its side overnight after coming back from the lake. The next day I noticed the oil coming out of the hole.

JWH0420 · Jun 22, 2011

Re: Leaking lower unit

oil from a lower unit that has a leak will appear milky in color and ranges from eggnog ish to oil w light colored swirls (in more minor cases) if u have gear lube leaking from above the fill plug more than likely ur leak is from input shaft seal or shifter linkage seal

dradford78 · Jun 22, 2011

Re: Leaking lower unit

The oil does have exactly this quality. Thanks for verifying. Do both seals that you mention require lower unit removal

JWH0420 · Jun 22, 2011

Re: Leaking lower unit

not familiar with a motor that size but i would assume its like the bigger versions and say yes

Daviet · Jun 22, 2011

Re: Leaking lower unit

Yes, the lower unit will have to come off.

dradford78 · Jun 22, 2011

Re: Leaking lower unit

To take the lower unit off the shift linkage will have to be disconnected if I read the manual correctly. Also I believe that this motor requires power head removal to reach the shift linkage. Is this correct and any suggestions.

Daviet · Jun 22, 2011

Re: Leaking lower unit

You don't have to remove the power head. Shift it into reverse, remove the four bolts holding the lower unit on and it should drop down a bit. It should drop far enough to expose the brass shift rod connector, remove the bottom screw and the lower unit should come off.
I think you shift it into reverse, maybe forward, which ever gives you the most clearence.

dradford78 · Jun 22, 2011

Re: Leaking lower unit

That's great news. I did see the connector you are talking about, but did not feel comfortable just unbolting stuff before I found out for sure. Will hit it up tomorrow and post results. Thanks everyone

dradford78 · Jun 23, 2011

Re: Leaking lower unit

So I got the lower unit off by doing exactly what was posted. Just undo the two bolts holding the shift linkage together. It looks that there is a gasket leaking (number 13 in the diagram Diagram) I am guessing that gear oil should not be getting on top of the water pump housing but there is residue on it. Does this gasket sound like a likely suspect.

boobie · Jun 23, 2011

Re: Leaking lower unit

As long as you have the g/c off have it pressure/vacuum tested. Takes all the guess work out.

Daviet · Jun 23, 2011

Re: Leaking lower unit

The only seals on the top side of the gear case is #12 and 16.
boobie is correct, the positive way to find the defective seal is to pressure/vacume test the lower unit.
If I had the lower unit off I would probably reseal the whole thing.

dradford78 · Jun 23, 2011

Re: Leaking lower unit

Im guessing that a pressure test would require taking it to an actual shop, or is there a kit you can buy to do it yourself. I looked over the top part of the lower unit and number 12 was the only part that I could see that was rotting off the lower unit and was the only thing that looked like it was leaking. #10 did not have any oil on the underside of it and no oil in #11 and #16 was dry.

Daviet · Jun 23, 2011

Re: Leaking lower unit

You would have to have a pressure tester to pressurize the lower unit. By the way you described it, it sounds like the drive shaft seal is your problem.

dradford78 · Jun 24, 2011

Re: Leaking lower unit

Ordered parts today and should be in next tuesday. Will post results when they come in

Leaking lower unit

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