[Jason in TX]

Wait wait... Why are you emptying the oil pan? Aren't you cleaning out the water passages? You don't empty the oil pan and then fill up the radiator hole with this. Chances are your oil pan area is fine since it's had oil in it. Your water pump is rusted because it has water there.

I have noticed that when you drain the stuff off the part, you are going to have to flush it pretty good because it is kind of slippery. Water has done a pretty decent job but I've sometimes helped it along by just rubbing my hands over the part to really get the slippery residue off