I have a 5.0L with around 144k mileage. I noticed a reasonably severe leak of anti-freeze the day after I had the oil changed at a shop (coincidentally?); nothing out of the ordinary on that day. The temp’s have never showed as being beyond normal, thankfully. I saw that there was a bit of weeping from the water pump, so changed that believing that the gaskets might be the real culprit (third pump on this truck). I re-filled the system with fluid (green silicate as the system had been modified several years back), ran the engine, and found that there is still a leak, not as severe, but most definitely bad. It honestly appears to be dripping at the oil pan gasket, just left of the crank on the lower end. The location doesn’t really seem logical to me. I’d love to hear what you think.
Do a pressure test on the system, a hose may have a small leak that sprays the coolant to an unlikely spot.
Did you put a sealer on the water pump mounting bolts and on the gaskets? Look closely at the gasket area. I have seen pumps leak at the gasket when the 2 lower bolts were run up tight before the top bolts were made even finger tight, causing the gasket to wad up and blow loose.
Freeze Plug leaking or check the heater hose connection at the intake. Mine leaked at this connection. It was cracked. There under $20.00.
Like oldbodyman I was thinking freeze plug, though I’m not skeptical of the other ideas either.