I have a 1999 Explorer with 104k miles that has developed an oil leak. I first noticed the oil at the back of the oil pan and bell housing and thought it was a rear main seal problem. After cleaning up the oil and running it for a while, there was no oil leak. I drove it for about 10 miles and then found more oil. I had a mechanic check it and he said that the intake manifold was leaking and the oil was running down the back of the engine.
I removed the intake manifold and found oil down in the valley between the heads. I cleaned it all out and re-sealed the crankcase breather (**** poor design there). After driving it for about 100 miles or so, I had oil leaking out the back again. I removed the intake and found oil in the valley again. I checked for where it could be coming from, but I can't find it. I was thinking either the crank case breather box (I sealed it pretty good so I doubt it), or possibly a head gasket.
Has anyone else had this problem? I would hate to do head gaskets for no reason. Thanks.

 

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Either i dont understand what you mean or,....

if you take the lower intake manifold off, there should be oil in the valley, but it shouldnt be getting out.

When you reset the lower gasket did you put a silicone bead on the valley ends and a peanut size blob where the heads meet the engine block?

Did you check the drains for flow?

 

It's the SOHC motor, the lower intake bolts directly to the heads, it does not contact the block or any oil at all. Down in the valley is the crankcase breather assembly and a temp sensor, that's about it.