An isolation mount assembly includes a rubber isolator formed to be seated within an aperture in a supported member, with an extension located on an exterior surface of the isolator; and includes a washer containing an aperture corresponding with a location of the extension. The isolator may include a through-hole and an inner sleeve, and be seated within a supported member. A method for temporarily securing a washer to a rubber isolator includes aligning an aperture in the washer to a corresponding securing feature on the isolator, inserting the securing feature through the aperture, pulling a detached end of the securing feature, pushing the washer towards the isolator until it makes contact with the surface of the isolator, and releasing the detached end of the securing feature. An exemplary method may include trimming or deforming an excess part of the extension after releasing the detached end.