I have an external coolant leak. I can see coolant dripping off the front of the oil pan; there was a significant puddle under the car after sitting overnight. I don't see any coolant weeping from the water pump. Is there a core plug in the front of the engine that could be leaking? It is on the front of the engine but lower than the water pump from what I can determined. I will need to get the car up on ramps so I can get under and do a proper inspection but I am looking for information on where to go hunting.

You need to take a look at it.

Here is an interesting thing, it isn't leaking when the engine is hot. Therefore, it can't be a core plug as the hole wouldn't shut with heat.

go rent or buy a pressure testing kit for a cooling system, put the right adapter on and then pump up your system to normal PSI.

If you have a leak, you will find it audibly possibly or just the source will be much faster. without a running engine/belts to complicate things

i would look at your lowerr rad hose, clamps. just to start at easy

Pressure tester is the best way to find the leak.
Call your local parts stores and see if they loan one. You'll likely need to pay for it but you get the money back.

I have determined it is the water pump. As far as I know, it is the original water pump so it lasted a good long time. I have ordered an ACDelco professional; which is an ACDelco certified aftermarket water pump. I figured it should met the specs or ACDelco wouldn't include their name on it. An OEM ACDelco was too expensive for my budget.

Yeah, you should be good. Weird that their "ACDelco Professional" line was less expensive than their "ACDelco" line.

My 1997 dumped its original water pump shaft gasket at 227,000 miles and 21 years of age. Your'* seems to be in the same ballpark by age at least.

GM pumps certainly last a long time. I got the1997 Pk Ave back in 2012 already 15 years old, & decided to install a new pump immediately after buying it.
Part number I used was 19209288, came with gasket.

I am not sure why ACDelco are calling their aftermarket parts Gold or Professional. I asked a friend that use to repair cars for a living about aftermarket as to what he could attest to. He advised SKP. I started to buy one but found the ACDelco Pro part at a good price. Of course I went looking for the explanation on these ACDelco Professional part and found this https://www.acdelco.com/about-us#:~:...20applications.

oh this is dangerous, Ac delco professional is fine, but they hitch their name to haywagons of **** if you find the right part so be careful lol