I have a antifreeze leak under here anyone know what that part is

 

Note not the thermostat but the opposite side
Where the hose fitting is

 

Yeah its part of the intake lower plenum. It means you've blown a water jacket. I would have a shop check it out.

 

It is for you heater hose and if I'm not mistaken, you'll have to replace the whole intake manifold to fix it.

 

Have a small shop look at it. Worst case you will have to get a new intakr which will give you more power anyways

 

I just fixed an expedition at work with a coolant leak at the rear of the heater fitting. Looked like a gasket leaking so I took the intake off and found the plastic part of the intake split apart. Needed a new intake manifold. Got the one I needed from NAPA. Dorman products makes a complete intake. Wasn't too badly priced. Took me about 2 1/2 hours for the whole job with installing new plugs and cleaning all the coils on the pass side. Came in for a misfire. Cleaned all the coolant from the coils and problem fixed. I have seen pinholes in the heads too, typically caused by electrolisis, eating through the aluminum. Most likely the Tupperware under the intake split.

 

I put it back together. Since there is one bolt that I could not reach without removing what seemed like the left side of the engine. I tried some Bars leak Radiator sealer and it worked. I'm shocked that it stopped the leak.