Heater core swap.

[smackattack]

I just changed the heater core in my 93 grand am and am haveing a hell of a time getting the water to circulate back through the system. I let the car run till thermostat opens and temp climbs real fast to hot. I shut it off let it cool and try again. I have repeted this 4 times and still no good. I even tried swapping the lines in case it was a one direction flow. What else can I do?

[Dragula]

Are you sure the thermostat is opening? Are the lines hot on both sides of it, and on both sides of the radiator?
Things to consider, check:
-Air in system, try loosening hoses, squeeze the lines until coolant runs out.
-Bad Thermostat
-Restriction
-Broken water pump vane.

Good Luck

[Chazman]

As Dragula says, most likely an air lock.

Look for the highest point in the cooling system, there should be an air purge screw, open it until a steady stream of coolant comes out.