So I bought a 2003 Chevy 2500 referenced in this thread here. The cooling system is questionable at best. Meaning the overflow has some gooey stuff in the bottom. It needs a water pump but I also wanted to flush the cooling system. So the issue is, as soon as I pour anything into the bottle it comes right out the weep hole in the pump. My plan is to swap the pump over, but not the new hoses, maybe even guy the t-stat housing that is in there and run it with no t-stat. Then flush the system with a cleaner, I have the Liquimoly stuff as well as citric acid. Then install the new hoses, t-stat, new reservoir, cap, and fresh coolant. The truck came with a free Gates pump, lien sale so I got other interesting things as well. If the flushing takes out the pump I will get a AC Delco one. I already have new belts, tensionors, and a 145amp alternator. So what does everyone thing about the plan? It is a bit extra work, but I want to do this sort of correct.