Weird coolant leak

[Turtle12400]

2007 4.0 SOHC with 130k ish

I've had a persistent weird coolant leak for a little now. When the radiator is filled and the overflow tank filled to the proper level, the truck pisses coolant out of the front cover area around the crank pulley until the overflow tank is dry and there is about a half inch of air in the radiator. After that, ZERO coolant leaks out and the truck runs and drives absolutely as normal. ZERO overheating issues at all.

I've had the thermostat housing explode already and I replaced it with a cast housing, so that isn't the issue. Hoses are nice and tight with worm gear hose clamps.

I have coolant dye in the system from that job, so that's making my life easier for sure. From my inspection so far, it appears that the coolant is leaking onto the crankshaft position sensor and dripping down from there. There is no play in the fan clutch pulley.

My thought is that the water pump is leaking, but before I really dig into it I figured I'd get some input from more experienced folks. Any notorious coolant leaks I should be aware of aside from the thermostat housing issue?

Thanks ya'll!

 

[Turtle12400]

Alright little update. As you can see, coolant appears to be gathering on the bottomside of the water pump housing. It seems like it might be leaking out of behind the fan clutch pulley? The coolant residue is on the bottom of the actual water pump housing and not coming out of the mating surface.

Would this match with the leak stopping at a certain point and not continuing to leak past that point? And does this mean I need a new water pump.

 

[PetroleumJunkie412]

Trippy.

 

[Turtle12400]

Trippy.

I've got red and green too.

 

[Uncle Gump]

It's not uncommon for a water pump to leak

And it sure looks like yours is leaking.