+1 and +1 again.
check the weephole for any corrosion/leaking.
the weephole is usually right underneath the pulley, so a mirror might help you get a good look at it.
a cooling system pressure tester would be an excellent help. if you have one, fill up the radiator with water, it wont work if the system is empty.
also, you can judge how bad the leak is by how quickly the gauge on the tester drops. and remember, 16 psi max.