A gas turbine engine rotor includes a rotor that provides a cooling cavity. The cooling cavity has a first chamber and a second chamber that are fluidly connected to one another by a passageway. At least one of the first and second rotor portions is configured to support a blade that is fluidly isolated from the cavity. A phase change material is arranged in the cavity. The phase change material is configured to be arranged in the first chamber in a first state and in the second chamber in the second state. The passageway is configured to carry the phase change material between the second and first chambers once changed between the first and second states.