Coolant loss

[RollinCoal]

I have seen it twice now, pressure test a system and it holds it over night, crank it and the gauge will just about break the needle off. Told the guys it was a blown head gasket and they said no way because it held the pressure.
So I ended up with my hands on it (boss telling me to fix it) pulled the head and found the fire ring in the gasket beat to shi#t and pretty much delaminated.
Put pressure on it and it would seal off, crank the truck and it would start pushing coolant out the overflow