Oil in Water

[Jb427]

I have oil in my water. I have owned my 390 fairlane for little over 2 years now when i bought the car i flushed most of the antifreeze out and replaced it with premixed coolant. That was about 18 months ago. There is no water in my sump there has never been water in my sump but my water is milky/black and thick with what looks like engine oil. i'm not sure if it is a reaction with the coolant i used and what was left of the antifreeze or something else its got me stumped.
can oil get into an fe water jacket with out water going into the oil/sump.
 

[Heo]

Yes the block can crack in oil gallery
up to rockers. It’s an easy fix but
You have to tear down the engine

[Jb427]

there is no real prob with running it long as no water is getting into the sump only needs to last a month or 2 before i'am ready to pull the engine ready for the 482?.

[a70eliminator]

The automatic trans heat exchanger could be culprit too so look close at the trans fluid condition.

[Jb427]

The automatic trans heat exchanger could be culprit too so look close at the trans fluid condition.

No trans fluid running through radiator.

[cjshaker]

there is no real prob with running it long as no water is getting into the sump only needs to last a month or 2 before i'am ready to pull the engine ready for the 482?.

If you're asking if it's ok to run it that way, it usually doesn't cause any issues to run it that way. I had an old 360 that I ran for over a year that way. As long as no water is getting into the oil pan, like you said, it should get you by. And like Heo said, it's typically the oil transfer tube that runs between the cylinders and up to the deck, then to the head and rockers.

[turbohunter]

Been running my truck like that for years. Only problem was the coolant I paid for in the beginning.
Cleaned it out and started running water only. Just turns the water grey. I check it when I check my oil as regular maintenance. In the beginning I would vacuum out the oil laying on top of the water in the radiator but as it gotten older the leaking has healed itself to where it's just grey water now. Doesn't affect cooling at all. Run it out to the desert all the time. It does freak you out in the beginning though.
Like the guys say, it's prolly a crack in the oil riser to the head as they run right next to a water jacket.

[Falcon67]

As noted, crack in some oil passages, cracked cylinder wall will also do it, possibly a failing head gasket seal in the right place(s).  I would change and flush the system, put in fresh and run it to see how long it takes to gum it up again.  If it's pretty quick, then I would not let it go - personally that is. 

[wowens]

Stock engine, my guess is migrating under head gasket to coolant passage

[turbohunter]

Stock engine, my guess is migrating under head gasket to coolant passage

Connecting the dots now that I think more with how it happened You are probably right. Since it was good for a while.
BTW just as a side note when I first found the oil in the water I pulled the engine back apart. And found oil migrating under the gasket to the water jacket. This is what got me to ask my brother to build a gasket that would eliminate that possibility. Fixing that is prolly why now I just have gray water from a crack and not a full fledged leak anymore.

[RJP]

Same problem with the 390 in my F-250. It was bad enough to really make a mess of my cooling system. I was prepared to pull the engine and have the sleeves [SBC push rods] put in the oil galleries to the heads. After doing a lot of reading on this problem such as factory and trade magazine service bulletins I thought I would try someone's recommendation of removing the head bolt closest to the oil hole in the block. 1st one I did was the passenger side and found traces of coolant on the head bolt. Used spray carb cleaner in the bolt hole and compressed air to clean and dry. Loaded the bolt threads with Permatex liquid thread sealer and reinstalled the bolt and let it sit for about 24 hours to cure. End of problem. Not all oil-in-coolant problem is a crack in the gallery but a small crack on the block's deck between the oil hole and the bolt hole. I got lucky as it worked for me, it may not work for you but at least it would be worth a try.

[turbohunter]

I should give that a try.

[cjshaker]

The tubular passage for oil to the head, and the area on the head gasket that Marc had an issue with are about the only areas that I'm aware of where oil can overcome coolant pressure and get into the coolant. If it were a cracked cylinder wall, you'd be getting water in the oil.

[turbohunter]

Yup