2003, leaks coolant when engine is cut off. It stops leaking when it cools down a little. And does not appear to leak when the car is running.

The coolant looks like it's coming from the weep hole near the crank pulley. Timing belt, water pump, and all gaskets were replaced about 12k miles ago.
I just installed a crossflow radiator, and I wonder if the increased pressure on the cooling system has caused this leak. The leak started after the first long drive with the new radiator.

A little Googling leads me to believe it is the small O-ring on the water pump. Currently, the car seems to be fine to drive, I just add a few ounces of water before each trip.
Other than the water pump, is there anything else I should check before I replace everything again?

I have already confirmed it is not the radiator hoses, and I'm pretty confident it's not any of the smaller heater hoses. Hard to get a look behind the pulley, but I believe it is trickling out of the small weep hole.

 

Are you running standard ethylene glycol coolant? Most glycol coolants are very UV sensitive and will glow under a blacklight. Grab a blacklight off of Amazon and shine it around your engine bay to ghave a better chance of knowing exactly where it's coming from.

If you're not running glycol, Autozone (and probably the other FLAPS) sell UV dyes for different engine fluids. Works just as well.

 

Coolant Pressure Tester is a small bicycle-pump that connects to the radiator cap. It can be rented from most auto stores. Pump it up to 12-15psi, any small weeping leak typically becomes a stream, way easier than trying to hunt down droplets.