I have a leak coming from somewhere behind alternator on 4.0 .
Anyone else have this before? I am thinking timing chain cover.

 

4.0l SOHC had a common leak issue from the plastic thermostat housing.

Coolant leak sources can be hard to trace, you can get a UV(ultra violet) dye kit(under $20), it has UV dye and small UV flashlight.
Run the dye in the coolant for a day(or two), then start trying to find the source while disassembling parts to get to it.
And keep in mind a leak can spray out, so where it is dripping may not be where it is leaking, those are a PITA to track down sometimes.

UV dye also works for oil leaks and even A/C leaks
Dye is inert, you don't need to flush it out.

 

Probably Thermostat housing. I just had to replace mine on my 2005 4.0. It was at the point where my truck would overheat after about 5 miles. It wasn't cheap to have the dealer do it. So get the parts if you can and do it yourself. Ford charged me $700 to replace it.

 

I had thermostat replaced last year with water pump. Its a Ford certified truck so I dropped off today to dealer. Also extended warranty still good.
I will let you know what they come up with.

 

Turned out to be the timing chain cover. They replaced a bunch of gaskets thermostat, coolant sensor and some other stuff. Glad I was still covered.

 

Thanks for posting the fix.