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Oil in Water

I have an interesting problem with oil-in-water in my 351W. That?s correct, oil-in-water, not water-in-oil.

I have a 65 Mustang that I installed a 351W. I have only 700 miles of this engine. I purchased a rebuilt short-block on-line (1979 date coded) and installed Edelbrock aluminum heads, intake and cam. The engine runs very well, no compression problems. I have a T-5 five-speed, so no trans cooler in the radiator. The oil pump is a Melling hi-volume. Oil pressure is about 60-65psi and steady, both hot and cold, at idle and at hi RPM. (Note: The only problem I have is that it runs very rich at an idle. I do not believe this condition as anything to do with the oil in the water.) This is not a severe leak, I?ve lost maybe 10-12 ounces of oil. At first I thought the oil in the water was some residue left over from the machining on the block during the rebuild. So, I flushed the coolant system (with a cooling system cleaning solution - by Prestone), and the problem continued. Also, I noticed that the heater hoses have experienced a ?sweating? of an oily nature. I had thought this was anti-freeze however, as soon as a mechanic friend looked at this he said you?ve got oil in the water. Removing the radiator cap revealed that there is still oil in the water.

My thoughts ? If the problem existed in an oil drain-back area (valve covers, lifter valley, etc), the water (at a higher pressure) would be forced into the oil. For the oil to get into the water, it must occur in an area where the oil pressure is higher than the water pressure. So, the only place I can think of where the oil and water are physically close enough to cause this is the pressurized oil feed passage from oil pump to the oil filter, and the filter to the crank/cam bearing area. A crack, or porosity, in the casting in this area could cause this condition. A leak in the pressurized oil passages in the lifter valley, or crank/cam area would only leak back into the oil pan.

Obviously finding, and than fixing, a problem like this will be difficult.

I can?t think of any other area, or condition, that would cause this problem.

I?m hoping that I?ve overlooked something simple and that you?ll be able to provide that quick, easy, low cost repair that will solve this issue.

Your thoughts are most welcomed.

Note: I have talked with Ford Racing Tech Service, Edelbrock Tech personnel and posted this to a Mustang blog site. No one has offered positive responses. Several people have said to replace the head gaskets but I’m having trouble rationalizing that is the problem.

Brainstorm,no idea is thrown out yet. Cooling system pressure test, any results?HC in coolant test,results? Heads off what area of the headgasket would be most likely to show a failure,a oil passage close to a coolant passage,if no result comes from headgasket inspection it leaves a porosity condition in the head or block,something I have never seen.

I have seen porosity in the head lead to external oil leakage. (BMW X5 6-Cylinder 2001 year model.

Shoot some brainstorm ideas by and eliminate the absurd.