GM uses a pump pressed on a shaft which never comes off. I have herd tell of the pump fins wearing off to the point that it doesn't pump but this would be an extremely rare event. The pump is only a few years old.
August, 6, 2011 AT 6:24 PM
Backflush the engine block and flush the radiator. All I can do is make suggestions, I can't see anything from here. If you don't like my answer, post the question again and I will leave you alone.