Ford Repair: 351C overheating/water pump air?, core radiator, head gasket

Question
Mark,

I have a 1970 Torino GT conv with air (nice car!) and have had no problems with it. Has the original 351C 2V engine. Now all of a sudden it is over heating after only 5 min of idling. The top hose does get hot so seems like thermostat is ok. It does not seem to be circulating water though. Is this just air stuck in the water pump? I do not drive the car very often, was ok a few weeks ago and has never done this before. The water pump appears ok (no leaks, bearings feel good).
Any advice on troubleshooting would be appreciated. What are the odds I blew a head gasket and air is getting to the water pump? Car is never driven hard and engine is rebuilt with only 8K on it. I should also add I am in Phoenix where it is now over 100 degrees so it heats up instantly. I also have a brand new 3-core radiator installed 200 mi ago.

Thanks and go FORD!

John

Answer
i've read both questions-first i would take a heater hose off and fill through the hose with the radiator cap off so it can push air back through the engine and out the radiator it is a slow process but if air is trapped this should get it out-if it sits alot then thermostat may be sticking but if it has enough coolant five minutes is to short a time at an idle-if it was rebuilt properly head gasket should be ok so i would go for the air-is water pump new-was cooling system clean i have seen fins eat off of water pumps and the would not circulate but at this time i would still lean toward air. good luck.