Lower unit water in?

Have a 1994ish M5B ULS.

Noticed when I drained oil in late early December it looked like this the attached. Note that it has been in the jar since December 5th or thereabouts.

It doesn't appear the "milky white" - but it didn't come out clean either...assuming this is water infiltration. NOTE: The area of "dark green" is slowly getting thicker relative to the lighter green area. It was originally about 25% of the current thickness when I drained the lower unit. Also, when I drained the unit I did not notice any water initially draining from the bottom.

So, with my Pressure/Vaccum test mightyvac...I tested at 8 inches HG - vacuum and pressure. It held vacuum for at least 30 minutes, then I release vacuum. When I pressure test, I notice some bubbling from the white seal that the shifter rod goes thru. But pressure loss was minimal.

Also pressure tested in a large bucket - no bubbles coming from prop shaft seal, or drive shaft area (although I didn't remove the impeller housing yet). I did see bubbles from the shift rod area.

The shift rod seal is only 3 years old as I installed a new water pump, drive shaft seal, and every other part associated with the pump and housing..(not just the impeller.). And of course I put new washers on the fill and level screws every year.

And yes I have a Factory and 3rd party repair manual.

Thoughts appreciated. Thanks in advance.

Looks like some minor contamination of the LU lube. Given bubbles from the shift rod area, that's likely something that needs attention. You do know that there are two o-rings for the shift rod bushing, right? There's the large one (35) that goes below the bushing, and there's the small one (34) that goes in a groove inside the bushing. That one can be tricky to replace. I use a stainless dental pick to extract the old one, and I install the new one by putting the (collapsed) ring in the bore, and then manipulating it with a punch the same diameter as the shift rod, and a tiny screwdriver... being careful not to damage the o-ring. Why do you have an o-ring on the shift shaft above the bushing, doing nothing?

Ha...crap...I was wondering what that 2nd smaller o-ring was used for.

The other o-ring is under the bushing.

In the manual it didn't indicate that the smaller ring needs to be inserted into the fitting... when I looked at the diagram, it appears to just be sitting atop the bushing. that made no sense to me when I installed it...should be fun getting that inserted into the bushing.

oh well...that solves the problem no doubt. thanks Paul.

One advantage of the Factory service manual, instead of just the parts catalog. First, get the old o-ring out. A dental pick is helpful. There will likely be some gear oil on the bushing. Use that to your advantage. Collapse the o-ring to insert it in the bore. Then manipulate it around until it clicks into the groove. I use a punch from one end, and a teeny screwdriver from the other end. Good luck !

So I have the factory manual (and an aftermarket manual) and I didn't see any discussion on that - will have to look at it again.

Thanks for the tips! Still love the old beast as it runs great and idles so well that people on the dock walk up to me all the time surprised it runs so well...