We used to call them "Cold Leaks" on the trucks.
As soon as the coolant warmed up they would stop.
Simple expansion and contraction of plastic lines. But still maddening.
Happy Glamping.Norman, 2008 Winnebago Adventurer 38J, W24, dozens of small thirsty ponies. Retired after 40 years wrenching on trucks! 2010 Ford Ranger toad with bicycles or KLR 650 in the back. Easy to spot an RVer, they always walk around with a screwdriver or wrench in one hand!