Please explain ......what seal is leaking

[dthx]

76 Johnson 25 hp
I know there is some info on this in the forum but I'm still in the dark.
Leaking out of weep hole in lower unit while in driveway....leaking down foot.
I checked the lower unit out....no water....took 2 tablespoons approx. of lower unit oil to fill again.
Could someone explain just what seal screwed up on or didn't replace......I replaced the water pump recently and was dismayed to see the oil leaking now...
Just what seal do you think is needing to be replaced?
It's kind of a ***** to take the lower unit off.....with the gear shaft to line up and all.....It wasnt easy.....for an old guy like me
But I'm going to fix it cause it's kind of cool having a 76 motor run as smoothly as she does.....
thanks for all the help

 

[racerone]

Answer the following.-----Did you replace the shift rod o-ring ??--------Did you pressure test the lower unit ?

 

[boobie]

Pressure AND vacuum test the lower unit !!

 

[Sylva-Ranger]

Are you sure it's lower unit (clear o?l ) ?

If it dark it's o?l from the engine.

 

[dthx]

Raceone and Boobie...I seem to remember a seal that I pushed the drive shaft thru so that it's splined end could mesh with the helical gear in the gearcase....that seal was made of metal with a rubber seal to go around the drive shaft.. I remember having to pry it out of it's place and tap the new seal in...I dont remember an o-ring.......been a while though ..
I didn't pressure or vacuum test the unit.....I dont have the setup for either.

Sylva-Ranger....I looked at the oil today and it is certainly very dark...not clear or light tan as the new case oil appears to be from the bottle
But I have never seen exhaust oil coming out there...or showing up on the foot anywhere but around and slightly below the exhaust port..looks like that dark color

Could the heat of the day be expanding the oil so that it comes out of the "hole"....the "hole" is the strangest thing...it looks like a plugged hole that was made somehow in the manufacture of the casting...I cant stick anything in it and it's not threaded.

I'm going to try to post a picture....never done that but I know it can be done....maybe that will help...
Thanks

 

[David Young]

Leaking black is normal. Just unburnt fuel and exhaust crap

 

[racerone]

The shift rod has an o-ring for a seal.----It is often overlooked by the novice repair man.---If it is original it needs to be replaced.---That hole is a casting cavity drain and it should NOT be plugged.

 

[F_R]

You say you have been searching the forum. In that case, you know that this is one of the most often asked questions. The answer is we really can't say for sure. However, it USUALLY is unburned fuel and oil running out the exhaust.

If the motor is in a vertical position, it is not the drive shaft seal. Oil would have to run uphill to do that. Besides, that much oil in a short time would be a major leak. On the other hand, the shift rod seal, if leaking, can come out in the vertical position. Without knowing for sure what drain hole we are talking about, that question remains open for debate. But if it indeed is leaking, it would be gear oil coming out--same color as what's inside. Black oil probably is fuel that has picked up carbon particles as it ran down through the nasty black exhaust housing.

So, why does fuel run out anyway? Several possible reasons. Is the hose from the tank disconnected from the motor? Could be pressurizing through a slightly leaking float valve, and on through the engine.

But reality says that SOME fuel discharge is normal.

 

[dthx]

Thanks....I'll take a picture today and upload it ...stand by

 

[dthx]

OK ......Here is a pretty good picture that I took today.
What say all of you?

 

[dthx]

Sorry ....I forgot to attach the picture.....
Here goes.....
Cant do it!!! error message says "Invalid file data DSCF0223.JPG"

What's wrong?

 

[dthx]

Very Frustrating to upload a picture.....not as easy as all my other forums....
So.....forget it.....I'm just getting angry and life's too short.
I'll go to another forum.
thanks anyway.

 

[oldboat1]

Scoop some up on your finger and smell it. If it smells like gas, it's unburned fuel/exhuast stuff. Don't fill the opening, but use some paper towelling to stop the dripping and/or put some newspaper underneath.

 

[boobie]

Take it into a dealer to have it pressure and vacuum checked. That way you know what you have. No guess work.

 

[dthx]

Thank you all for the Help.
Went to the River this weekend and notice that after bringing the boat to the campsite, I had oil leaking out the weep hole again....this time it was gray.....like it had water in it.
I drained my lower unit oil and there was definitely water in the oil....
So....the lower unit comes off tomorrow.
I will definitely replace the gear shift rod o-ring.
Question...Will I be able to see where the oil is leaking from when I take the lower unit off....?
And might the drive shaft seal be the culprit.?
I know how important it is to "test ...not guess".......but I will not be able to do a vacuum or pressure test....unless there is some poor boy way of doing it.....

 

[racerone]

Actually there is a poor boy way of doing it.-----------You reseal the unit.----------Assemble the lower unit.----------Install the drain and vent plug.-----------Put the assembly in the hot sun for an hour.------------Now remove one of the plugs.---------You should hear pressure escaping !

 

[dthx]

Very cool !!...Thank You.
I'll try that...

 

[jimmbo]

Filling it with oil and doing the heat thing, might actually show where the leak is since liquids don't compress

 

[dthx]

I found the leak to be around the shift rod bushing (between the bushing and the housing) .....I took it out and I remember replacing the o-ring and the gasket below it....the o-ring still looked big and fat...and the gasket looked OK.....Ive ordered a bushing, o-ring and gasket ...so I'll replace all....
One thing
I noticed that there is a shaft lip seal around the propeller shaft....it's inside what they call the gearcase head assembly......($154.00) but that seal specifically is not called out in the parts list.....
what say all of you?

 

[racerone]

Simply remove the washer on the outside.---Then remove the seal.--Measure the shaft.----Measure for OD of seal.-----Find and install a new seal !!