Ok here is the deal.

Truck left a 1' circle of coolant on my driveway tuesday moring while warming up(about 10*). Checked coolant level and was about 1" down in overflow tank. No obvious leaks so i went to work(1 hour/50miles).
Once at work checked and still no obvious leaks and level was the same. before i left work i looked for any wetess, saw nothing, drove home. Once i got home w a flashlight i looked deeper. I found some coolant on thermostat housing, and on A/C line running under harmonic balancer. So i took a jug of hot water and rinsed everything off. Went to Advanced to get coolant pressure tester. Got home with truck and everything dry. Went to use pressure tester and it was broke. Brought it back and they would get me one for today. Drove truck to work and back, no leakes today. Picked up the NEW pressure tester and put it on. And pumped it to 16psi. No leakes but loosing pressure SLOW(2psi in 5min). pumped it up to 22psi and still not leaks but loosing pressure.

Any ideas? I pulled fan shroud loose and dont see anything wet on the back of rad. Now i dont see any coolant since i washed the engine off yesterday.

My ONLY idea is that it was SO COLD that the water pump seal didnt seal and coolant bypassed the seal. once it warmed up the seal sealed and stoped the leak. I am lost

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04 Supercab 4dr 4.0 5spd 4x4 EDGE. Daily Driver
96 F350 Crewcab 460 5spd Vortech S/C 4X4 6" 35s
94 Lightning Bassani headers back CAI Underdrive Pulleys
86 F250 Reg Cab 6.9 4Spd 4x4 6" 35s (powerstoke,D60 5spd on the way)
80 F350 Reg Cab 429 C6 4x4 L&L headers F450 rear springs All Out Pulling Truck(D60 Laddered Frame, 540cid coming)