2005 Chevy Suburban Where is my leak coming from?

I have a coolant leak right above the crank shaft pulley but right below the pulley above it. I know its coolant because of the color ( pink ) and the smell of it ( like syrup ). I have a 2005 Suburban. The leak only happens when the temopo reaches 210 degrees . Then a steady stream flows from thar area. I watched and waited under my vechile to see the origin of my leak. Also when we tyr to use the heat only cool air blows.