I replaced a heater hose the other night - the one that runs from the block to the valve that connects to the firewall, the old hose had a pinhole where it clamped to the block.

The new hose is tight on both ends, but there's a dripping leak near the valve where the aforementioned hose connects. The new hose is clamped tight, so I know it's not that.

It's either the other hose (from valve to firewall) where it connects to the valve, or the valve itself. Could someone tell me as much about this valve as possible? I felt a small circular opening in the bottom, is there normally a screw or something that goes in there? How does it work? What is the technical name for it?

I can't get underneath the car to look, all I can do is feel, and I can't determine if the leak is coming from the hose that runs from the valve to the firewall, or the valve itself.

Thanks in Advance, please respond ASAP!!