Milky oil - Twin 454

[beech2000]

Starboard engine our 90 Sea Ray Sundancer continually has milky looking oil. Two oil changes since last February, 110 hours now have accumulated with no operational issues. Still the same creamy looking oil noted. Today a third oil change and same milky oil. Closed cooling antifreeze level stays normal, antifreeze has normal lime green appearance with no external leaks.
Since no external leaks and no antifreeze loss that I can tell in closed cooling, guessing I'm dealing with lake water intrusion or moisture from somewhere..... Hoping Don S will chime in. Intake manifold gasket? Cracked head? Cracked block? Oil appears thick and lubricity seems normal. No operational temperature issues eitjer. Not suspecting large intrusion just annoying discoloration and loss of sleep for same. Thoughts?

 

[GA_Boater]

Don can't answer. RIP

The milk has be coming from a place other than the motor's cooling system or you would be losing coolant.

That eliminates all you mentioned. Could the oil be aerated and you're seeing bubbles?

What all is connected to the cooling hose from the lake? An oil cooler, perhaps?

 

[alldodge]

Pull the plugs and see if plugs look white as being steamed cleaned. Exhaust may be leaking water down cylinders

 

[Scott Danforth]

2 places for water to enter oil in a closed cooled motor

first place is oil cooler - pressure test the oil side. should hold 100 psi all day long

second place is thru the exhaust either thru reversion of a cracked elbow or bad gasket (full system) or a cracked manifold or elbow or bad gasket (half system)

 

[tank1949]

Starboard engine our 90 Sea Ray Sundancer continually has milky looking oil. Two oil changes since last February, 110 hours now have accumulated with no operational issues. Still the same creamy looking oil noted. Today a third oil change and same milky oil. Closed cooling antifreeze level stays normal, antifreeze has normal lime green appearance with no external leaks.
Since no external leaks and no antifreeze loss that I can tell in closed cooling, guessing I'm dealing with lake water intrusion or moisture from somewhere..... Hoping Don S will chime in. Intake manifold gasket? Cracked head? Cracked block? Oil appears thick and lubricity seems normal. No operational temperature issues eitjer. Not suspecting large intrusion just annoying discoloration and loss of sleep for same. Thoughts?

I read this, and a lightbulb went off in my head. Has it rained a lot? I had rain water come in via deck-hatch drip line and into valve cover blow-back opening or carburetor. It was a weird accident! Milk on dip stick and inside ONE valve cover (if my old memory servers me correctly)... I panicked and replaced oil and added small tarp on top of my MC V8, just to hope and be sure. It never happened again. So, it was either sabotage or rain intrusion. It didn't take much rain water to scare the H out of me and suspect a potential rebuild. My motors were saltwater cooled. Good luck!