Clamp not tightened enough
This happened to us in our 21 CS. We took it to Cummins, and we were told that a clamp was not tightened enough, probably from the initial build. This allowed the coolant to leak out. I did not see the tech tighten the clamp, but after he tightened it and poured over a half a container of coolant in, our generator runs as it should.
Paul & Casey Loranger
2021 Entegra Cornerstone 45B
2020 Chevy Silverado, Blue Ox, SMI AF One