[64speed]

The other night I ran some usual errands and on the way home I had the low coolant message come up. Gauge never went over 210 which is where the 5.3 has run since new. Got home and went to garage and got laser temp gun and it wasn’t hot anywhere. A few minutes later my wife comes in and tells me that water is just pouring out of the Yukon. I went outside and sure enough the driveway was soaked. Filled it up with water. Went and drove around for a little while came back. No problem. Took it to a radiator shop today and they pressure tested the system and nothing. Visual inspection shows no sign of leaks. What am I missing?