I came upon a great deal on a '98 Saturn, and had to replace the radiator. When I did the job I noticed the radiator overflow tank. This tank had a tube running from it....nothing unusual there, cause all the cars I own have similar, but the tube on all my other cars just runs down toward the underneath of the body, and vents out overflow to the ground. Now on this Saturn that tube runs around the back of the engine and attaches to a port that enters the back of the throttlebody area. I've never seen anything like this before. Can someone illuminate me on this tube and what it'* function is for and why does it enter the intake?