Have you removed the thermostat? If the upper hose is hot and the lower hose is cool, you probably need a water pump. A few quick, inexpensive things to do to check for a blown head gasket: get a pressure test on the cooling system. (Most auto parts store will lend you the kit); perform a hydrocarbon test (this tests for exhaust. Gases in the coolant and costs about $30 at NAPA.) GL!