coolant loss continues

[georgeramos]

If coolant slowly slips into the overflow tank and leaves air in the main system is this a cap failure? Is this even a possible cause for my endless coolant loss?

[bradartigue]

Maybe. Caps are so cheap...replace it with an original type and move forward in diagnosis. When working properly the expansion of coolant will send some of it to the tank, then as it cools it will return to the radiator. If you are going just to the expansion tank and never back then I'd suspect the cap is not regulating itself (opening too fast, closing too early, probably needs viagra).