Why am I losing Radiator Fluid when there is no leaks to be found?

The smell is typical bad heater core, but if you are losing that much fluid you might want to do a combustion leak test. the kit is about 40 bucks. It sniffs the coolant system for combustion gasses. It will tell you if you have a bad head gasket.

Well A head gasket isn't hard to replace...I am worried about the Heating core....How does the Combustion leak test work?

it uses a test fluid that you use a vac pump to pull air from the radiator or coolant reservoir through. it is a colored fluid and if it changes color then you have combustion gasses in the coolant. that means the head gasket is bad. I dont know much about Chevy cobalt, but I would think that a heater core would be easier than a head gasket! But with these modern vehicles, you never know.

Had someone put a new radiator in is it supposed to be lose and now i am loseing transmisdipn fluid the lines look good they put orings in but still leaking