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Discussion Starter · #1 ·
Anybody make one? I see a couple options just surfing the web but was interested in other potential options.

Lower unit looked a lot more tan/brown than I've ever seen in years past...
 

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Looks like Lake Erie water !
 
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Basically just trying to find where a leak might be by putting a few psi of air to it. Hoping its something silly like a bad vent screw gasket but could be worse. Motor is 21 yrs old so...
There are several different seals that could be leaking. I have a 1982 Johnson 25 hp. Tried several fixes , didn’t work. Now I just change the oil every fall .
 

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Thinking about making one as well this winter. Planned to cut the end off an old gear oil pump - plastic screw with clear hose - and jury rig it to a quick disconnect for the air compressor. Only needs to hold a few psi.

Three places for seals - prop/gear/drive shafts. Plus the 2 filler plug washers, sometimes the fiber ones need to be scraped off if they get mashed in. Fixing the seals and gearcase stuff on smaller motors is pretty easy, though there are some helpful “tricks” to know. Haven’t dug into the bigger HP with shims, but I’m gonna have to soon.
 

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Discussion Starter · #8 ·
There are several different seals that could be leaking. I have a 1982 Johnson 25 hp. Tried several fixes , didn’t work. Now I just change the oil every fall .
I change every fall. That's how I found it. Usually a tiny amount of white but this time was very different. I don’t want to open it up next fall to find half water.
 

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Just reseal the whole gearcase, seals are cheap. most likely from fishing line on the prop shaft. Removing your propeller a couple time a year to check for fishing line behind the thrust hub is an easy measure of prevention. Don't forget, the seals on the fill and vent plug should be replaced every time you change the lube.
If you pressure test it, no more than 12 psi. I have seen guys blow out seals using to much pressure.
 

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Discussion Starter · #10 ·
Just reseal the whole gearcase, seals are cheap. most likely from fishing line on the prop shaft. Removing your propeller a couple time a year to check for fishing line behind the thrust hub is an easy measure of prevention. Don't forget, the seals on the fill and vent plug should be replaced every time you change the lube.
If you pressure test it, no more than 12 psi. I have seen guys blow out seals using to much pressure.
Easy to replace plug gaskets, shifter And under water pump but isn't the prop shaft seal a PITA requiring special tools?

This could just be plug seal wasn't 100%. Hoping pressure test to around 10 psi will help me find it.
 

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Not always are special tools needed, i have changed a few with a standard seal puller made by Craftsman and some picks to pull the seal off the shaft, care must be taken. you don't want to score the shaft.
 

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Discussion Starter · #12 ·
Not always are special tools needed, i have changed a few with a standard seal puller made by Craftsman and some picks to pull the seal off the shaft, care must be taken. you don't want to score the shaft.
Most people have hammers, screwdrivers and wrenches. I dont have a puller of any sort. But I have an acquaintance who is an airplane mechanic so he probably does.
 

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No one around you with the right tool setup?

Theoretically...you could probably put the top/vent plug in the drive and then put an old gear oil pump nozzle on an empty bottle and pump. Soapy water on the seals once it's pressurized. Even a bike pump would work if you could get a good enough seal.
 

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Discussion Starter · #14 ·
No one around you with the right tool setup?

Theoretically...you could probably put the top/vent plug in the drive and then put an old gear oil pump nozzle on an empty bottle and pump. Soapy water on the seals once it's pressurized. Even a bike pump would work if you could get a good enough seal.
I talked to a guy this afternoon that has enough crap to make something work. Just not exactly ideal. We talked about a regulated air supply to 10 psig and saying screw the "does it hold" test and just use soapy water as detection. I have a filler pump and the screw fitting for it so i think i will get good enough seal to push air out of any leak point. He's got a puller that's probably long enough, too. Probably all set.

One thing I need to do though is flush some clean oil through to get as much of the brown crap out as possible. Plain ol cheap motor oil okay for that?
 

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What brand of gear oil was drained? Differences between OEM, synthetics, and standard 80-90 weight. I use Valvoline in my engines with good results. A little water homogenizes and usually will turn the oil milky, unless it's set for a while and separated. Very possible everything's OK. Make sure it's drained before freeze.
 

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Discussion Starter · #16 ·
What brand of gear oil was drained? Differences between OEM, synthetics, and standard 80-90 weight. I use Valvoline in my engines with good results. A little water homogenizes and usually will turn the oil milky, unless it's set for a while and separated. Very possible everything's OK. Make sure it's drained before freeze.
Quicksilver marine gear oil. I've seen a small amount of milky oil before but this is far more than I've seen in 9 years of annual changes. I will say "most" of the oil coming out was still very dark. Not greenish anymore but relatively clean.

It has been draining probably a total of 8 hours now. Its in an unheated garage so a little slower than normal draining.
 

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Put the oil in a milk jug or something clear, let set and see if there's separation.

Pressurizing the internal case will most likely not be best because in application, the pressure is external.
 

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Take the top vent screw out and find a piece of small hose and blow air - or compressor - and it'll drain the remainder out. Could be a little messy. Should only have about a quart +- a little. At least make sure the top vent screw is open. Laughed at my neighbor and it tricked me once. He had a top drain for the lower unit and a flush plug that looked the same and were side by side on his Yamaha. Had the flush screw out and couldn't figure why it wasn't draining.
 

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The presence of a little water could be from condensation.
 
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