Water in the Oil Problem

[gdasw]

I have been struggling with water in my oil the past 2 seasons. The water does not appear to be gushing in but rather more slowly. I had clean oil at the start of the season and have run the engine about 4-5 hours and it is starting to go milky. I have a Tartan 30 and the exhaust goes out the front (flywheel) end of the engine and then out the side.

I have completed the following tests and changes:
- tested compression (twice) and have the following 90(1)-90(2)-100(3)-100(4)
- tested my exhaust manifold with the recommended pressure test and it appears to be OK
- pressure tested my block (three times) with the recommended test and it also appears to be OK
- redid the hot exhaust to get the point where cooling water is injected lower and father away from where the exhaust exits the engine. I was concerned that water was going back into the exhaust manifold.
- rebuilt my MMI water pump per a recommendation from Don
- checked the plug that apparently was put on the valve side of the engine on certain engines (serial no 194000 and higher – my engine is 195000 something) but could not find it

The engine starts up right away and runs well. The engine is fresh water cooled, seems to be in good overall condition and has always been in fresh water. I don’t know what else to check or test or do next. Any suggestions would be very welcome. My next step is to call a mechanic but of course I was hoping to resolve it myself.

Thanks in advance
Geoff

[Marian Claire]

Sounds like you have checked most things. So my 2 cents may be worth just that. Is there any way to monitor the fresh water level to see if it is dropping? Can a dye be put in the water that would show up in the oil if that is where the leak is? And is it possible to have a small hole in the low end of the cylinder that would let water into the crank case but not effect compression? More question that answer I know. Dan S/V Marian Claire

[joec43]

Is it possible you have a pinhole in the fuel pump membrane (mechanical type pump).
I was getting small amounts of water in the oil that way, rebuild kit fixed it right up.

Just a thought, something you don't have listed, but then you may have an electric pump....................

Good luck,

Joe

[Marian Claire]

Check out the post “3 out of 4 ain’t bad”. Don mentions a leak below the combustion chamber. Dan S/V Marian Claire

[Marian Claire]

More thoughts and questions. The MC is raw water cooled so I am guessing about the fresh water system. If it is a closed loop then a leak between the crank case and the cooling loop would not show up on a pressure test. What if you disconnected a line in the cooling loop and then pressurized the block? I am also guessing about how the pressure test works. I have obviously been away from my boat for too long. Dan S/V Marian Claire

[Don Moyer]

Geof,

I won't go into any long-winded explanations, but is there a possibility that your engine is a Stevedore model that was originally exported into Canada. You can check by removing the carburetor and inspecting to see if there is a small round restriction installed just inside the manifold flange where the carburetor mounts. The restrictor was installed friction tight and reduced the ID of the flange by approximately 3/8".

Also, do you note a decrease in coolant in the expansion tank or heat exchanger.

Don

[Marian Claire]

Disregard my ideas on the pressure test. I now understand how the test works. Should have done my homework first. Sorry. Dan S/V Marian Claire

[MikeB.330]

Have you check around the sea water pump for any signs of a leak? I remember read a post or two about the oil seal failing and allowing a small amount of water to get in to the crankcase.


RE: the fuel pump idea, I don see how the fuel pump would have anything to do with water in the oil unless the pump was pumping water and not gas.

[gdasw]

Thanks for all the replies. I made a mistake in my original posting, the engine is raw water cooled (with fresh water) not fresh water cooled with the additional heat exchanger. Also I have an electric fuel pump so that is not the souce of the water.

We purchased the boat in Cleveland and brought it up to Canada so I am guessing that it is not a Stevedore version of the engine. I will check the carb to see if it has restrictor but I am guessing that it doesn't.

Is it possible that I have a small leak in the head gasket that is small enough to allow some water in but not effect my compression too much?

[gdasw]

I checked the engine this weekend and it is not a Stevedore model.