Re: 2006 150 optimax lower unit removal
I have a smaller engine but probably similar. Looking at the leading edge of the LU 1" or so below the anti vent plate you can see a small hole, maybe .100 inch in diameter. This is the pickup and water routes internally and back out the plastic rt. angle connector that is at the front of the mid section, via the tube back to the speedometer on the dash. I don't see anything internally in that circuit. Everything seems to be cast in place and there are no seals or anything else mentioned in my serv. manual. So, if yours is like mine, there is nothing to worry about other than maybe ensuring that the mating surfaces between the LU and MS are clean and of uniform height so that the two castings align properly.
This seems a somewhat vague interconnect if you ask me. One would think that there would be some sort of seal to ensure that there is no leakage between the two castings but there are none shown.
Mark