Where's my oil leak coming from

[R J Bezesky]

Hey y'all,
My '06 Mountaineer has a refurbished 4.0.
This is the second one from my motor guy (the first had a rod knock) and it runs good.
Bad news is a pretty heavy oil leak on the back of the engine bellhousing area. It's too much to live with.
It leaks it seems mostly while parked not driving. New valve cover gaskets (dry) no leak from the rear tensior or filter adapter.
Is the likely leak the rear main seal or upper pan, or something else all together?
Also could a stuck pcv valve cause an oil leak to be bad while sitting? I have to do something soon, it's getting worse.
Also I've cut ties with my motor man (incompetence) and shame on me for not doing more research and using him in the first place.
But this is where I'm at.

 

[boominXplorer]

My bet is on upper oil pan, it will leak if you do not clean out the divots where the tabs go in the rear.

 

[R J Bezesky]

The Mountaineer is AWD. Should I also inspect the rear main. What is best scenario takling this situation. Drop trans, drop front diff or pull engine? The upper pan makes this more complicated doesn't it, or can I attempt upper pan with engine in vehicle?

 

[boominXplorer]

The rear main seals rarely leak. Your going to have to at minimum remove the front differential, cross member and sway bar to get the oil pan out.

 

[R J Bezesky]

Great, I'll give that a try first. I might also mention that the first bad engine I got from my motor guy had a bad leak in the back of the engine as well. Perhaps not cleaning divots out on the upper pan is standard practice of his.