I run 7 pounds, cuz my system is rock-solid. some of my hoses are older than ancient.
If your upper hose collapsed cold, Ima guessing your rad cap failed to hold pressure when hot and blew off steam. Then when the coolant cooled, it contracted, produced a low-pressure inside the systen, which allowed atmosphere to crush the weakes link which was the upper hose.
In other words;
Either the cap is no good, or
or is of the wrong design, or
your system has a problem, or
some combination.
Depending on your location and/or elevation, my guess is that ;
1) your cap is faulty, and/or
2) your flex-fan is not doing it's job, and/or
3) the missing shroud is a contributor, and/or
4) your expansion tank is not working correctly, and/or
5) your temp gauge failed to inform you of a stick situation,
6) or some combination
