3.7LX with oil in coolant

I know this sounds crazy, but I have a 3.7LX with oil in the coolant system. I flushed it in hopes someone inadvertently put a qt. of oil into the system, ran it and the oil reappeared. I've checked everywhere to see if there's an oil cooler, but I just find the filter housing with a screw-in bushing and o-ring. I also found an "oil cooler cover" on the bottom of the intake manifold with 2 passages that I assume line up with passages in the manifold. The breakdown didn't show any seals for the passages. Am I now to assume I have a cracked intake manifold? It seems to me it's the only place the higher pressure oil can penetrate the lower pressure coolant system. If the front seals were blown, I'd have coolant seeping from the weep drain at the bottom of the front cover and I don't. There's also no water in the crankcase and the engine runs good.
Has anyone run into this before or have a remedy?

Re: 3.7LX with oil in coolant

Could be the head gasket. All you need is a leak between a water passage and an oil return passage (0 pressure) and you have water in the oil.

Drain the cooling system, and pressure check it. You might even be able to hear where it's leaking if it's very quiet.

Re: 3.7LX with oil in coolant

Don, I think you read that backwards, he is getting oil into the cooling water, not water into the oil.

I dont think its the head gasket as there are no pressurized oil passages between the head and block to allow higher pressure oil to get into the cooling system (You may have a blown head gasket anyway, just because this is a 470 after all, and thats just what they do ).

The intake with an oil cooler is the 4 bbl model, the 2 bbl version doesnt have this. There should be two hoses that run between the manifold and the oil filter housing. I would agree that the manifold is probably cracked. Pressurize either side of the manifold, the oil side or the coolant side, and you will probably find your culprit.

Findng a replacement 4 bbl manifold wont be fun if thats what this ends up being. They pop up on Ebay every now and then but they never seem to go cheap.