300zx radiator problem?

[SeanK]

Fix the leaking hose, fill the radiator and overflow tank. Start the car and bring up to temperature, all while watching and listening for leaks.
Identify and repair further leaks.
Wash, rinse, repeat.

Also the dash temp gauge has three positions. Cold, operating temp, and your about to warp a head. If you ever get the temp gauge moving North of normal, investigate. I'll second what the previous poster suggested and say check for milky oil.