My car is not cooling down right. 1. my radiator was leaking, fixed 2. new thermostat 3. new heavy duty fan 4. water pump good The gauge fluxuates, it goes up and then down. When its parked and idleing, the guage reads above half on the 2nd line from half, but when I drive it goes hot and then comes down and right back up. It pulls the fluid from the resivoir.
How old is the radiator cap? It's probably the easiest and cheapest part in the system to replace. If it won't hold pressure, you won't cool down. I agree with Eric. Since you say that the gauge has a line and I assume, no numbers, I'm guessing it's a factory electric gauge. Electric gauges from the factory are cool things. Unfortunately, they are inaccurate and have been since they were new. There is no substitute for a good mechanical gauge. On a 15 PSI system like yours, you are good up to about 230*F with no trouble. Your boil over temp should be rated to 247*F on a 15 PSI system, which I'm guessing you have.
On a stock temperature gauge for the 70-72 GS, the halfway mark is 210. Your reading 2 lines above that. I'd say you are running hot all of the time. You say the thermostat is new, it may be defective if the temp goes up and down. How sure are you of the radiator? Could it be clogged? Are you running 50% antifreeze or less? Do you have a fan shroud, and a working fan clutch? You should get a good mechanical water temp and oil pressure gauge. That way you know exactly what the engine is running at. I agree with Chris, check the cap, that's easy and cheap. Where is your timing at. Retarded timing will overheat the motor.
