That doesn't make sense to me. 210-215 is a normal engine temperature so the radiator has to be working. Coolant is coming out from underneath the new radiator cap or it is flowing out into the overflow container? If the coolant is spewing out from under the new radiator cap, you probably just didn't get it tightened all the way. If the coolant is overflowing into the overflow container, it probably isn't the right pressure model cap, it needs to be an 18 lb. pressure cap.