I have a 2005 Dodge Neon, its been over heating a lot. When the car was idle and running I noticed a water leak... When looking under the hood it was coming out of this drain tube that runs to the heater core? Someone told me it could either be the water pump or the heater, My question(s) is What happens if I seal that tube off or Is there a way to find out which is bad out of the two?