An internally cooled turbine vane for a gas turbine engine has coolant flow channels between the interior walls of the vane and an insert, where the channels serve to convey a portion of the cooling air flow from a pressure side chamber to a suction side chamber. The turbine vane defines a radially extending passage with a dividing wall defining a front section and a rear section; the rear section having interior walls spaced apart from an insert to define the pressure side chamber and the suction side chamber. The insert may receive cooling air and conveys the cooling air into the pressure side chamber and the suction side chamber. A front surface of the insert or a rear surface of the dividing wall may have a clearance gap and an air flow channel communicating between the pressure side chamber and the suction side chamber.