I personally think that the hard hose in the morning test is useless, and your experience has shown the reason why:

Your hose doesn't get hard even after the engine is starting to get warm, it is painfully apparent that there is a leak, most likely a bad cap on the expansion tank.

If there is any leak, it will lose pressure overnight, even if the head has a crack you could shove a penny through. You first need to fix the pressure leak, so that the system has noticable pressure/firmness in the upper hose as soon as there is some heat at the heater hoses off of the head. Next, you go the car with the engine completely cold, should be no pressure felt in the hoses, start the engine. The hose should NOT pressurize right away, not until there is some heat/expansion which should take at least a minute on the 60x engine. If it pressurizes right away that indicates that there are gasses escaping the combustion chamber through the head (or gasket) into the coolant. If it pressurizes after a minute or so, the head is warm and the water is starting to get warm, normal. If it doesn't pressurize even after there's enough heat to feel it in the heater hoses, you still have a leak.

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Gone to the dark side

- Jeff