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My season is over, and as a matter of habit, I always drop my lower before I put everything away. Years back I learned the hard way: trapped water froze, expanded & cracked a housing. Since dropping & draining is a 10 minute job, I long ago decided “why not”? It’s just part of my winter storag procedures.
Anyway, this year, along with about a cup of water, I was greeted with a foamy green slime in the impeller housing area….I figured “water in the gear oil”, so I drained it. (It was new oil & pressure tested in March before I launched)
This is a sample of the gear oil I used (West Marine 80W-90), dark green, on the right. On the left is what I drained out. In years past, my drained oil looked good enough to reuse. This year…nope! This looks like water got in, right?
Here’s the part that has me confused: I figured I had to find out where it’s leaking, so I did a pressure test. My gearcase has been holding 4PSI for an hour now. I can turn the shaft, manipulate the shifter, etc. and the gauge remains at 4PSI.
But it also occurs to me: keeping pressure *IN* doesn’t automatically mean the unit can keep pressure *OUT*….but what other means do I have to test / verify? I have no pressure chamber to verify the ability of the unit to keep pressure out.
Still, 4PSI is about 9 feet of water, so I would like to think that any seal that could handle 9′ H2O in one direction could surely handle the pressure associated with the immersion depth this is exposed to in normal operations. Or maybe not. Anyway, it sure looks like water got in, right?
Or should I just put in clean oil, seal it up and wait for next season? Do I need to split the gearcase / skeg and clean everything?
If you spray some soapy water on the seals, shift rod seal, and fill/drain plugs, it will help to isolate any leaks. Using low air pressure is better than high air pressure as too much pressure can force the seals lip against the shaft which will give a false no leak condition.
one hour in a bucket at 11PSI…not a bubble to be seen… Manipulated the shifter, wiggled it a bit…turned the shaft, wiggled it a bit too. No bubbles at all.
1.) interesting note (above) about testing with lower, not higher, pressure. But I’m closed up for the day. I’ll try that tomorrow night.
2.) when I initially put it in the bucket, I had bubbles where my hose fitting went into the housing. I had to tighten it quite a bit more than I would have suspected. This whole thing could have been as simple as a bad seal on the upper plug…
3.) If re-testing with lower pressure doesn’t reveal anything, I’m ready to declare the seals to be OK and chalk this up to a bad seal on the plug.
Am I missing anything?
It was raining when I wrote my previous post, but it stopped, so I went back outside & repeated the test at 2PSI. No bubbles at all…
So I became convinced this must have been a fill port plug that wasn’t sealed well enough.
But then I got to thinking: If there were water in my gearcase, that would be the limit of my issues. But I have this foamy wet oil up around the upper seal, so that made me think that was the spot where the leak was. I cleaned most of it out before I started taking pictures, but here’s an example:
So I re-pressurized and added soapy suds to the shaft seal and the shifter o-ring. Nothing. Not a bubble to be found. It’s not shown, but I lowered the pressure to 2PSI…still no bubbling. I’m a bit stumped.
O-ring soapy…no bubbles:
Upper seal soapy…no bubbles
Thoughts?
Or just re-fill with new oil & see how it goes next season?
Also, there’s this:
Finally, you may want to consider using some of the better OEM lower unit lubes that are made to “absorb” a certain amount of water without losing much lubricating qualities.
I’m all ears. Any recommendations?
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