Sounds like a fancy set up ,if its running scuppers for water pick ups and you have a flush point ,and both motors seems to run same shut the water valve by scupper pull dump hose off exhausts and add 15psi see if it holds ..can pull dist and peek into valley with small mirror and look there too . Start easy and work your way in

And wow kamma manifolds huh ? Haven't seen any of those in eons

I winterized them bondo. 8 gallons of antifreeze per motor. Plus it sits inside a shed that doesn't drop below 40 So it had minimal time out in the elements. The trailer ride to the lake from the shop would be the only time out and it was 60degrees out so I'm pretty sure it's not poor winterization

Thanks for all the info guys this def helping. I was wondering what kind of manifolds those were my self

It could be as simple as condensation not burning off. Is there an increase in height on the oil level or just milky????

Do you have thermostats????? I could be just very cold lake water going through the crossovers and not building enough temp.

After I switched from a circulating system to crossover , I would occasionally see the oil turn a little milk - shake , running it hard for a few minutes took care of it ...this was an older Mercury HP465

Ayuh,.... Then freezin' seems to be 'bout the most remote of possibilities,....

Do as airjunky says,...

Drain the coolin' system, block it off/ isolate it, 'n plumb in a pressure gauge, 'n air fittin' to pressurize it,...
It oughta hold 15 psi pretty much Forever,....

If it don't,... follow the sound of the escapin' air,...

http://i147.photobucket.com/albums/r...3AF99DA85C.jpg

I drained a little bit of oil out of each engine to take them to get samples it's pretty obvious which is the one with the problem I think it's a little more than just condensation another person told me to check on condensation I wish that was the problem I don't think it is think it's a little more deeper than that

Yea that looks to be a little more than condensation . Good luck on the exploratory surgery and it is good to see that you keep a close eye on your machine . Welcome to OSO . There is a wealth of knowledge here .

if you find that you have a bad manifold their was a thread with some for sale a few weeks ago..