Great video! I Remove the idle above the pump and the pump pulley, it gives you a lot more room to work. I also always mark my belt when I remove it, sometimes flipping them when reinstalled, it will get an annoying chirp. I also always clean my pulley surfaces, because coolant will get on them. I can't stand a chirping belt.
Not saying your diagnosis was wrong but in my experience, if the water pump is leaking from the rear it's not a bad pump, it's the gasket. The water pump is designed to express coolant via the "Weep Hole" (located at top side of the water pump on this particular vehicle) because the bearing's/seal is compromised. With that being said, if the water pump has more than a couple year's on it, might as well just swap it out for new. Great DIY video by the way. Thanks! 👍
For this particular model truck, you would _top off_ the radiator after the water pump replacement. Leave the cap off the radiator and start the engine to check for leaks from the pump replacement. Shut off the engine, reinstall the radiator cap. Do any further coolant addition thru the reservoir tank on the passenger side.
No, not according to the GM factory service manual written by the engineers which designed this, which I referenced. Typically, with GM designs, you _either_ use gaskets _or_ sealant - never both together. At most you might use some gasket retainer, a chemical to help keep the gasket adhered to the part until everything is lined up.
Also this one is sure more straightforward than the 6.5L diesel. I followed your video on doing the water pump on my 6.5L, especially for ordering the 300 different gasket makers / thread sealants / thread locker / etc etc required!
