New LS3 start up but no water flow through radiator

[David Pozzi]

I bought a GM crate LS2 years ago. While poking around it, I shined a flashlight up into the water pump heater hose fitting. I saw a bunch of red core sand plugging it up! I think that's why GM took it off the assembly line and sold it as a crate engine, they probably had a batch of them like that. Always take a good look at new parts.