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Water in the oil

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I can see milky oil through both valve cover caps on my 1992 Merc 454 Mag. No rust visible through the holes. The dip stick looks fine, but it has a fat plastic covering on it which might wipe off any evidence. The remote mount filter has just the slightest hint of cloudiness, which I probably would have missed if I wasn't looking for it. Regardless, there's clearly milky oil sitting in the low spots in both heads.

The engine hasn't been overheated to my knowledge. It is possible that last fall the overnight air temps went below freezing before the engine was winterized.

I've never been down this path before, and don't know where to begin. Are there some typical places that should be checked first? Do I try further diagnosing the location of a leak with the engine still in the boat? Or do I pull the engine and drive directly to the engine shop?

Of course, we leave for vacation with the boat in 31 days.
 

Paul65k

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That's almost always been a head gasket for me.....with cars mostly though :grumble:
 

mobboss

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When was the last time you changed the oil??? Sometimes its just condensation and sometimes its a big issue .pull the value covers wipe off the milky stuff put them back on change the oil and run it. see what she does. thats what i would do be for pulling the motor.
 

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When was the last time you changed the oil??? Sometimes its just condensation and sometimes its a big issue .pull the value covers wipe off the milky stuff put them back on change the oil and run it. see what she does. thats what i would do be for pulling the motor.

I changed the oil this spring, and have had the boat out three times since.
 

mobboss

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hot day? cool nights??? if thats the case it MAY cause that.
 

obnoxious001

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I can see milky oil through both valve cover caps on my 1992 Merc 454 Mag. No rust visible through the holes. The dip stick looks fine, but it has a fat plastic covering on it which might wipe off any evidence. The remote mount filter has just the slightest hint of cloudiness, which I probably would have missed if I wasn't looking for it. Regardless, there's clearly milky oil sitting in the low spots in both heads.

The engine hasn't been overheated to my knowledge. It is possible that last fall the overnight air temps went below freezing before the engine was winterized.

I've never been down this path before, and don't know where to begin. Are there some typical places that should be checked first? Do I try further diagnosing the location of a leak with the engine still in the boat? Or do I pull the engine and drive directly to the engine shop?

Of course, we leave for vacation with the boat in 31 days.

You may want to drain some or all of the oil. You can start with just a bit, since any unmixed water is heavier than the oil and should drain first, assuming you are using a drain hose rather than a pump. Is the oil level higher on the stick than when you changed it?

Another thing, if you haven't run the engine very hard in cooler temperatures you may develop condensation that hasn't burned off. The oil needs to get to 212 degrees to burn off any water condensation.

If you are convinced that you don't have much water in the oil, and can run it somewhere locally, you can go and try to get it hot and see if the milkiness clears up some, or start with fresh oil and do the same thing, go run it and verify that you aren't having a problem before you take it on vacation.
 

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Thanks a lot for the feedback guys. I'll drain a bit out of the pan tonight and see how much water appears. The lakes up here stayed much cooler than normal this spring because of the super cold winter, and I noticed that the temp gauge was low the last time I ran the boat. I doubt it reached 212F. I'm hoping that your condensation ideas are correct.
 

Dalton

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Could be exhaust manifold water leak-reversion
 

Dalton

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Take them off and Hook a hose up to them with the other holes capped, see if it leaks into the actual exhaust area, seen them fail close to exhaust ports and there's like alittle suction when the motors running and it pulls the water back in, if I remember correctly this happened on some stainless basset water jacketed headers
 

Dalton

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It's pretty much pressure testing them
 

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The oil from the pan shows zero water or cloudiness. Thanks for talking me off the ledge. I had no idea condensation could introduce enough water to appear in the heads.
 

obnoxious001

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The oil from the pan shows zero water or cloudiness. Thanks for talking me off the ledge. I had no idea condensation could introduce enough water to appear in the heads.

Sometimes it's better to be safe than sorry.
 

was thatguy

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The oil from the pan shows zero water or cloudiness. Thanks for talking me off the ledge. I had no idea condensation could introduce enough water to appear in the heads.

Absolutely it will.

It is a great idea to have an oil temp gauge. Without a closed system or a thermostat setup (Which you may have?) you really have no idea of true operating temps, regardless of what your water temp shows on exit.
 
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