Water in Oil

[Guy Bordelon]

I have a newly acquired Newport 30. On the first long sail we ran out of wind and had to power back in. I notice that the engine was running hot at 160 degrees. Oil pressure was at normal 40 PSI. At dock I found that the oil was gray so it was contaminated with water. Up until this time the engine had run OK.

I flushed the oil twice and ran the engine for 1/2 hour. It is staying at 130 degrees and the oil is now also staying clean. I did notice that the temperature jumped quickly from 0 to 130 when the thermostat opened rather than gradually moving up.

I am thinking that the thermostat stuck closed and caused the temperature to go to 160. This then caused the water to back up into the oil.

Questions:
1) Is this a possible scenario?
2) If this is what happen is there a possibility of other damage and what should I check?
3) Is it worth the expense to pull the head and replace the head gasket?
4) What other checks should I do?

[Don Moyer]

Guy,

I'll answer all of your questions with the statement that a 160 degree water temperature (particularly in a late model engine) and 40 psi oil pressure is perfectly normal for an Atomic 4.

Water in the oil is definitely not normal, however, but whatever caused the water intrusion has nothing to do with your slight temperature variation or oil pressure. Each year, we hear of slight water episodes like you're describing which clear up after several oil changes, and for which no specific reason is ever discovered. In these cases, we assume that a bit of engine cooling water splashed back into the manifold (and on into the engine) from the exhaust system.

I would definitely keep an eye on your oil for a while, and you might do what many folks do to minimize the chance for water to back up from the exhaust system, which is to keep your raw water through-hull valve closed while sailing. In fact, the through-hull valve is best kept closed at any time that the engine is not being used, particularly in your case, until we get a better feeling regarding where the water may have come from.

Best regards,

Don Moyer