Yes, you should be able too see coolant flow in the radiator. No it should not "violentlly blow out of the radiator." You sir seem to have a blown head gasket.

To the OP, the heater core has nothing to do with engine cooling performance. If you replaced everything you said you did, and everything is working like you say (fans and such), you may have a blown head gasket as well.

Both of you guys need to get a cooling system pressure tester. Pump the system up to spec, it should hold the pressure. If it does then run the engine and get it hot then perform the test again (be carefull taking the cap off hot). If it dont hold pressure you need to find the leak. If you cant find a leak its probably in the engine. If there is no coolant in your oil its probably in your cylinder and that explains everything.

Also you can take the vent hose off the radiator (the top one), and run a different hose into a can of water. If you get bubbles out of it you're in trouble as well.

 

Blown head gasket is a good possibility, but I don't think it could be that since he says he can still drive the car down the highway just fine, and it only gets hot in the city.

 

Thanks to both of you.

I've heard the blown headgasket theory before, but as 69 says, I would have thought other symptoms would have made it evident. I'll look for a pressure tester, and try that though.

Again, thanks.