Water pump OEM FORD or GMB

Sounds like your water pump is shot. The impeller is spinning on the shaft and not pushing the water. I just had a customer who had this problem. The crazy thing is, I just replaced the pump about 2 years/30K ago with a GMB pump. He had the exact same symptoms as you: car gets hot, but does not overheat, no water through the return line, and fan takes a long time before it turns on.

from 88k to 150k miles, I put in a new water pump ($27). otherwise very reliable and easy to find parts as there are tons of them in the junkyards.

The 3.5 5th generation Explorer has an internal water pump driven by the timing chain. It’s an enormous pain to change requiring significant disassembly (nearly 12 hours of labor) and generally includes replacing the timing chain in the process since you’re already in there, plus when it fails it can easily mix the coolant with the oil and destroy the engine, all that’s keeping them apart is a little seal.

I have a 2021 BS BB and I’m on my 3rd water pump replacement. 1st one around 20k miles, 2nd at 40k, now at the dealer with 51k miles and replacing it yet again.

I put in a GMB in my '02 two years ago, and it's leaking already.