A method for sealing a gas turbine engine includes coupling a turbine bucket to a rotor wheel and forming an interface region therebetween. A cooling air passage is defined in a portion of the rotor wheel and a cooling air manifold is defined in a portion of the turbine bucket. The method also includes inserting a seal tube within at least a portion of the cooling air passage. The method further includes coupling the cooling air passage, the seal tube, and the cooling air manifold in flow communication to at least partially define a turbine bucket cooling system. The method also includes operating the gas turbine engine such that the rotor wheel and the turbine bucket are rotated, thereby inducing a pressure on the seal tube to substantially decrease air flow discharged from the turbine bucket cooling system through the interface region.