2004 Saturn Ion coolant leak

Your going to have to get a coolant pressure tester to pressurize the cooling system then see where it leak's out.

You could try renting one from auto zone there expensive though to buy one for a good one. If you have a harbor freight tools by you they have a universal pressure tester pretty cheap that might work for your car. Using it depends on which adapter you have for your car. They have one that screw's on like your cap and they have one that fit's in the opening of the bottle. That one expands inside to seal it tight then you hook up the hand pump pump up the system watch the gauge and don't pump it up to the danger zone. Then look for leak's or you could add coolant dye but that's messy I like pumping it up.I haven't seen those car's leak coolant much except for the water pump's. So without seeing it or even really no what area it's leaking I would say it could be the pump. But pump it up and see where it leak's.