The water level on our Sorento has been going down but it doesn't leave a puddle on the ground but you can smell antifreeze. When we drove it today I could hear a whistle sound coming from the rear of the motor but then I added water & it started a really funny sound & then the water started to bubble out. I just figured that was the water & heat coming out of the overflow tank. Once we put water in you don't hear the hissing sound.

I took that big cover off & looked around but can't see any leak so I was wondering if it might be leaking from the heater core??????

Any suggestions would be helpful....