Top hose hot , bottom cold...new radiator

After rereading I see what you meant about flow direction. Which leads me to think about lower hose possibly collapsing. Which in turn would create pressure on top but not boottom.

I will put new thermostat in ... But kinda want to minimize time chasing issue.

I would assume there would be no pressure difference if Tstat wasn't opening.

Couldn't see where small drip was coming from. Fan may have evaporated it too
Quickly.

I have also been chasing a huge P/S leak... Put new pump on and still have big puddle....
I suspect the cap.... But double gasketed it and still a puddle ? Might have to take the fan off and run for a few minutes to trace leak sources... Wait a minute , is a leak a food ? Or is a leek a food ? Lol