An internal combustion engine cylinder head has a coolant jacket with a first supply opening and a first discharge opening. A cylinder block coolant jacket has a second supply opening and a second discharge opening. A coolant circuit connects the discharge openings to the supply openings via a recirculation line and a heat exchanger. A control unit has an inlet connected to a pump outlet, a first outlet connected to the first supply opening, a second outlet connected to the second supply opening, and a single setting element. The setting element has a first working position that opens up the first outlet and blocks the second outlet such that the coolant circuit is activated through the cylinder head and is deactivated through the cylinder block. The setting element has a second working position that opens up both the first outlet and the second outlet.