Subaru Repair: 96 outback overheating, upper radiator hose, radiator cap

Question
I have a very nice 96 outback. except it is overheating. Starts and runs great for 6 or 7 miles. Then the temp spikes. There is no knocking or pinging during acceleration. The coolant appears to be solid green (no brown from exaust like my last bad head) How can i tell if it is a water pump, clogged cooling system, radiator, or the expensive head gaskets. Any advice as to where to start? I can't afford a mechanic to do a series of tests. I can do the preliminary tests. Where to start? Jeff

Answer
I would replace the thermostat, its on the front of the engine where the lower radiator hose hooks up to the engine.  When you fill the system with coolant remove the upper radiator hose where it hooks to the radiator.  Fill the hose until it is full, this will fill the engine block with coolant.  Hook the hose back up and completely fill the radiator.  Drive the car and see if it overheats.  You could possibly have a stopped up radiator, while you have the lower radiator unhooked take a water hose and spray in the radiator cap opening and see if the water runs quickly through the radiator or wont blow through.  If it doesn't run quickly replace the radiator.  The water pump doesn't typically go bad on a subaru unless it is leaking. Hope I could help you!