Finished replacing my water pump (64k miles), belts, and upper/lower radiator hoses (and,of course, the fan shroud that got trashed when the water pump went out!).

Filled radiator through expansion tank. Started car. It warms up to th 12:00 needle position on the gauge after a few minutes and drove around block. Gauge stayed at straight up position, tons of heat blowing into cabin.

Pulled back in garage. Top radiator hose HOT - but bottom hose cold.

What's going on? Do I have air in the system? Shouldn't the coolant in the radiator be circulating through top and bottom hoses all the time? Over-filled?

Thanks!