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Johnson 50 HP 1995 water in oil but holds pressure.

T

Telfish

New member
I went to change my lower unit oil to find it milky, The oil separated into water and oil. Immediate thoughts are a damaged prop seal, water pump seal or gear change shaft. So I did a pressure test and sprayed soapy water on the prop seal and upper oil change screw, no bubbles.

Left it at pressure for 6 hours and no pressure drop.

So could it be the bottom oil drain screw gasket as that is the only one I cant test with a sop/air test?
 
The drain/vent screw washers absolutely could be an issue. Another thing to try is pressurize the case, then spin the driveshaft and prop shaft by hand and also move the shift shaft up and down. It's possible there are bad spots that are revealed by moving those components.
 
kevinj said:
The drain/vent screw washers absolutely could be an issue. Another thing to try is pressurize the case, then spin the driveshaft and prop shaft by hand and also move the shift shaft up and down. It's possible there are bad spots that are revealed by moving those components.
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Thanks .

I did pressurize the case and it help steady for 6 hours with no drop. Will try your suggestions.
 
So I re- pressurized the lower unit , put it in and out of forward and reverse multiple times, no change in pressure, spun the prop shaft backwards and forwards many times , no drop in pressure. So the only thing I need to test is run the motor and see if the water pump causes any drop.

If not can I assume that all internal seals are good and that I need to replace the drain plugs seals?
 
Seals wear out over 30 years.----If you can not afford a simple seal kit.-----You can not afford the gears , shafts and bearings , if in fact they are available.
 
Telfish is absolutely right, common problem and an easy fix.

I've had gearcases pass pressure test and fail vacuum test. I use Stevens test equipment. Old school,the best. But usually, pressure test is adequate. I would make sure you scrape the fill and vent screw counterbores with a pic to squeaky clean, make sure the fill and vent screw, screws are clean and replace with the correct seal washers, when I was a kid at a Evinrude dealership in 1975 the part number was 311598. I memorized it because we sold 100's of them. Number probably changed by now!
 
fitz73222 said:
Telfish is absolutely right, common problem and an easy fix.

I've had gearcases pass pressure test and fail vacuum test. I use Stevens test equipment. Old school,the best. But usually, pressure test is adequate. I would make sure you scrape the fill and vent screw counterbores with a pic to squeaky clean, make sure the fill and vent screw, screws are clean and replace with the correct seal washers, when I was a kid at a Evinrude dealership in 1975 the part number was 311598. I memorized it because we sold 100's of them. Number probably changed by now!
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Thanks for your response. I have some of the correct seal washers for the lower drain plug, the upper one looks like a standard o ring which I should also have. Will clean the threads as you recommend, then refill with fresh oil and do a run, then drain to see if I still have the issue. I really do not want to do a complete tear down of the lower unit if the solution is a simple fix. If it fails and water is still getting into the unit I will have to replace all the seals.
 
Can't you test the seal of the drain screw by pressurizing the lower unit using the upper fill hole? Seems like a simple solution, but maybe I'm missing something here.
 
halbrodmann said:
Can't you test the seal of the drain screw by pressurizing the lower unit using the upper fill hole? Seems like a simple solution, but maybe I'm missing something here.
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You could but it;s a smaller thread size than the standard size bottom screw, so would need a special adapter.
 
Drain the oil.------Put plugs back in.-----Put bag of ice cubes on lower unit.-----Remove drain plug.-----Do you hear a slight " puff " ?-----Tighten plugs and put lower unit in the bright sunlight for an hour.----Loosen drain plug and again do you hear a slight puff ?
 
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