Abstract: A method is provided for repairing by solid state diffusion a damaged portion of an inner surface of a hole of a metal part. The method comprises machining the hole to a cylindrical diameter sufficient to remove the damaged portion therefrom and provide a new hole with a smooth finish into which a metal bushing is inserted, the outer diameter being of size and finish relative to the machined diameter of the hole to provide a close fit therewith, the composition of the metal bushing being compatible with that of the metal part. A cylindrical metal mandrel of diameter corresponding to the inner diameter of the bushing is inserted into the bushing to provide an assembly thereof with the metal part, the metal mandrel having a mean coefficient of thermal expansion greater than that of the metal bushing for a selected solid state diffusion temperature sufficient to provide pressure against the bushing.