This guy I found on the you tube recently did a teardown of a bad 3.5 ecoboost. I'm assuming the architecture is similar to that of your Explorer. It's crazy how much work it is to get to the pump in addition to how horrible it can get if it starts to leak.So I started the car yesterday afternoon and the return hose was leaking out the top of the hose. So, I added another clamp. I was later told to rotate it 180° and will do so eventually.
I still left the towel under it as an experiment to see if it was still leaking and low and behold, this morning there were drips on the towel. I took a picture from the underside:
Im at a loss other than replacing the pump. it appears to be leaking from the largest of the hex nuts where it meets the body of the pump. The exposed O-ring is still dry.
It's going to have to stay like this for a while. My wife's 2014 explorer needs a water pump. For those of you who dont know, the water pump is inside the motor and run off the timing chain. Dealership wanted 3-5k to replace and I said no thanks, Ill figure it out myself. So, that's going to be my next mountain to climb...