Milky oil. :(

[Airshac]

So in a car I’d say well the head gasket is the primary suspect. Can I assume the same with this engine? I read on another thread about the gasket replacement and it doesn’t sound too hard, I am a mechanic by trade. Anything I should be aware of particularly with this engine?
I’ll keep researching on my own, just looking for advice from anyone with experience.
Thanks!
Edited to add, yes I did overhear the engine . Sometimes my own stupidity surprises me. The engine ran with out water. I checked the water pump afterwards and the impellers were still in good shape. I didn’t have the seacocks open and ran for about 45 minutes.

[ndutton]

I'd start with two tests before taking things apart, a compression test and a water jacket pressure test. The combination of the two tests may (not guaranteed) give an indication of where the incursion happened. If it was indeed the head gasket the compression test should indicate it. If it was the water jacket, water pump or manifold the compression test will be good and the water jacket pressure test will fail. In the meantime, squirt some oil into the spark plug holes and turn the engine over regularly, even daily if you can. Wherever the water came from it can wreak havoc if things rust up and the repair will become much bigger.

Once this is behind us, do you have a plan so the oversight never happens again?

[Surcouf]

so if cars had their exhausts mixing exhaust gases and cooling water... we would see milky oil more often

Milky oil could also be a sign from water back flowing to the engine due to wrong exhaust lift design, extended cranking without closing the water inlet valve etc..

As mentioned above, pressure testing of the cooling water circuit (manifold + head) will rule out the gasket, and should be done first.
good luck

[jbsoukup]

make sure your anti-siphon loop is functional.

[Trinity]

Milky Oil

I too have milky oil. I'm not great with computers and can't figure out how to begin a new post so if it is okay I jumped in on this post as I have similar issues with my oil. I spoke on the phone with Ken at Moyer Marine for probably 30 minutes about what to do. Based on the info I gave him he suggested I do repeated oil changes. ( I believe this was primarily because the oil level wasb't really increasing on the dipstick other than the very first time before the first oil change when it was actually 3X higher on the dipstick above the full line.)
Ken said it could take up to 10 oil changes to get the water residue out of the engine. I have now done 10 consecutive oil changes, and still have greyish milky oil. I have also taken the sea water pump off twice to inspect, replaced the impeller (which was actually in good shape) and pressure tested the pump with a bicycle pump and gauge. I also pressure tested the exhaust system at 20 lbs (albeit while the engine was cold). I isolated just the exhaust manifold for one pressure test and for the second I plugged the water intake hose and connected the air pump to the hose leading from the exhaust manifold. In all cases the closed system held at 20 lbs. I'm just wondering if anyone has suggestions on what I can do next to get to the bottom of the water in my oil? Would it be okay to try "K seal" in the exhaust system to try and plug any holes that might be in the exhaust manifold by building a closed system with hoses from the water inlet and outlet and a 5 gallon pail of water and "K seal" to be flushed through the exhaust system?
Thank you as I'm both new to this forum and a new sailboater with a 1971 CnC Corvette with a 30 hp atomic four.

[Airshac]

I'd start with two tests before taking things apart, a compression test and a water jacket pressure test. The combination of the two tests may (not guaranteed) give an indication of where the incursion happened. If it was indeed the head gasket the compression test should indicate it. If it was the water jacket, water pump or manifold the compression test will be good and the water jacket pressure test will fail. In the meantime, squirt some oil into the spark plug holes and turn the engine over regularly, even daily if you can. Wherever the water came from it can wreak havoc if things rust up and the repair will become much bigger.

Once this is behind us, do you have a plan so the oversight never happens again?

Thanks for the input, I’ll do those checks before moving further. As far as never happening again, yeah this won’t happen again! I learned my lesson the hard way.

[ndutton]

Thanks for the input, I’ll do those checks before moving further. As far as never happening again, yeah this won’t happen again! I learned my lesson the hard way.

Moyer Marine offers a basic oil pressure and temperature alarm system (would have alerted you much earlier as the temperature rose beyond the trip point) that can be enhanced by their raw water flow sensor (would have alerted you immediately). Some forum members prefer to hang their ignition key on the raw water intake thru-hull valve handle when the boat is not in use as a reminder.

[Airshac]

Milky oil could also be a sign from water back flowing to the engine due to wrong exhaust lift design, extended cranking without closing the water inlet valve etc..

As mentioned above, pressure testing of the cooling water circuit (manifold + head) will rule out the gasket, and should be done first.
good luck

I'm going to go with extended cranking with water inlets open.
After the overheating incident I did a compression check and all cylinders were fine there. I checked the oil for signs of head gasket damage and didn't see any signs of water contamination.

When i did find the milky oil was after the engine had sat for about a week and was a little hard to start. I didn't have my trusty can of starter fluid so I spent about 20 minutes cranking, letting it sit, cranking again, fiddling with the choke, etc till it finally fired up.

When I get back to the boat I'll do the pressure tests, change the oil and and start the engine with the water valves closed (sop from here on) and see how the oil looks afterwards.