Here is the reason.
I wonder if this happened at the factory?
The second pic is the side that leaked.
Don't think it would have been long til the other started dripping either

 

i cant really tell but is that grease/dirt that is getting between the gasket or is the edge completely gone?

im glad you finally figured it out tho... im gonna have to take my cousin's water pump off this weekend.

 

looks kinda like corrosion maybe?

 

The gasket was pushed into the coolant passage. It probably barely sealed from the factory and as dirt and crud got in there it finally leaked.
Like I said in my other post it barely dripped, some days not at all, some days quite a bit.
What you see in the pics is exactly where they were on the truck, they stayed on the water pump when I pulled it.
The **** was driving me nuts!!
I gotta get back out in the parking lot and finish it up now. I'm doin it at work today because my boss is out of town.

 

Great pics. It made me go out and take a look at my daily driver....2001 5.3 stock ECSB 4wd. I got the creeper out and slid up under the engine up front and sure enough, ive got what looked like tranny fluid up front. I quick test of it however reveals its coolant (Im running the orange Dex stuff). Sure looks red like tranny fluid from the underside, but the kicker is that it smells like antifreeze. Had to take the front skidplate off to see the source of the leak, but with a flashlight, there is just enough room to see up through the harmonic balancer to that port of the water pump. Sure enough, its leaking out the bottom passenger side...damn. FWIW, I'm at 140k on mine...just noticed it, and had it not been for your pictures and following your trouble, I'd have never suspected it. Thanks for the "heads up" on this one.

BTW, did you RTV the o rings when you put the new pump on, or did you put them on with grease? Am I going to run into any issues with hoses or clamps while I'm in it?

 

well i am glad you found the prob, I was almost like I knew what I was talking about in the first thread, LOL.

 

I did not RTV the gaskets before I put them on. The seal is built into the metal gasket itself. The stock gaskets had no extra sealant apllied either.
The trick is to get the sealing surface absolutely clean, I mean no contaminents at all or it will eventually leak.
I scraped the block clean with a razor blade, then a brass brush and then some shotch-brite. Be carefull if you have an aluminum block!!
Mine is cast iron.
When you clean that area just jam some paper towels into the passage ways to keep the crud from getting in there and rinse it down with clean water and dry it off good.
When your done cleaning and rinsing it off pull out the paper towel and anything in the passage way comes out with it.
I think all you need to replace a water pump is a 3/8" drive ratchet and 3" extension, 15mm socket, a 10mm socket, and some good pliers or vise grips for the hose clamps.
To get your fan off just get a big adjustable wrench on there and make sure its snug and give it a couple of wacks with a rubber mallet, it will come loose.
The fan is a conventional right hand thread on my "02" just in case you were wondering or yours won't come off.
Its a very easy job, the biggest pain was getting off the hoses without ripping or tearing them.

Slammed10, thanks for your help! My pump was still good but I figured what the hell, replace it while I'm in there. Who knows when it would have went, I'm over 60k miles now.