[Ron61]

One other thing that I never saw mentioned and this happened to me once on one of my cars is the small outlet tube for the overflow came loose and my pressure tester would not show anything. But I could drive it for a little and there would be coolant leaking. Finally I cleaned and dried everything off around the radiator cap neck and then started looking by trying to move something and that small tube had a very small crack in it where it was soldered to the neck. I had already changed radiator caps, checked the hose from the tube to the overflow tank, and that was all that was left. I soldered it again and never had another problem.

Ron