Courier Overheating Problem

I have a '79 Courier that blew its top! It began to overheat a short while back. I replaced the thermostat and the radiator cap. The next time I drove it blew the radiator cap along with the raditor spout (that the cap locks on to). I took the radiator and had the spout welded back on. After I reinstalled the radiator I put the old radiator cap back on. I drove it home - 60 minute drive. It began to overheat and then it blew it's top again??

Possiblly the water pump????

some of the impellers in the old pumps would actually rot away from rust and corrosion and render the pump useless even though it is not leaking. squeeze the top radiator hose when engine is at operating temp and you should feel a strong surge of coolant rushing through, if not suspect the pump. Otherwise you may have a head gasket leak causing hot exhaust gases to enter the cooling passages, thus super heating the coolant and causing overheating. Hope that helps..Joe