Cooling system problem?

[oldskewel]

Originally Posted by andrewwynn

I think more likely just head pressure vs. air pressure. I'm not aware of any check valve that could actually cause pressure.

I'm thinking more that things were under pressure when it was warm, and then it just held, even as things cooled and contracted. Kind of like how if a garden hose with a trigger nozzle is pressurized and then turned off at the hose bib - the pressure is retained in the hose until the trigger is pulled, and then the pressure releases and the hose contracts slightly.