2002 TrailBlazer Water Pump Leaks only at low pressure.

There was no doubt I had a coolant leak as it was all over the engine compartment. However, the system held pressure and showed no leak when I pumped it up to anywhere from 10 to 14 psi. I remembered once having a tire leak that was only found when I lowered the pressure and could flex the tread a little. A leaking tire is not exactly pertinent to this situation but the normal operating pressure of my system is likely just a few psi so I decided to have a look with the system just marginally pressurized. BINGO!!