As the temperatures are dropping below freezing and our Rock Fish fishing is heating I thought I would play it safe and check the oil in my lower unit. I change it early this summer and it was fine. When I checked it now it was very milky. I drained the oil and pulled the lower unit as the water pump need changed anyway. The engine is a 2004 150 HP Yamaha 150TXRC with 150 hours on the clock. Here?s my quandary. I pressure tested the unit and it holds a consistent 11.5 psi. It will hold this pressure for over 24 hours. My Yamaha manual calls for a holding pressure of 10 psi. Next I ran a vacuum test at 5, 10 and 15 inHG vac. In each case it held each of these levels for as long as I left the vacuum pump installed (several hours). The manual makes no reference to a vacuum test. During both tests I rotated both the prop and drive shafts and tried to push them in and pull them out to see if I could cause a leak. No leaks. Has anyone experienced a situation such as this. As milky as the oil is, to me it looks like water intrusion and not just condensation. Accordingly, should all the lower the seals be replaced or should I just replace the water pumps and refill the lower unit. I would hate to disturb the integrity of the lower unit if I didn't have to. Heck, the engine isn't even broken-in yet.
Stumped
Stumped
