1968 Dart cooling system & gauge Questions

As Dana wrote and the MTSC explains, the 'leak' is in the design.
Master Technician Service Conference - Chrysler's Training for Mechanics

With the Chrysler systems at that time, they only become pressurized when there is vapor pressure.
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View attachment 1716545075OK, Tech. Set me straight.

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Thanks. I just watched the video this morning. So my system is operating normally then. And there was slight pressure this morning when I pulled over at work and checked the hose