In this paper, a vibration endurance test is performed on rubber insulators used for vehicle air cleaners. Based on the test results, the endurance characteristics depending on the type and the material of the insulators are estimated. The frequency response characteristics of the air cleaner system including the insulator are investigated to identify the cause of wear and failure of the insulator. New insulator models with improved endurance characteristics are proposed and tested. Test results show that the vibration endurance property of the insulator is strongly dependent on the frequency response characteristics of the air cleaner system as well as the deformed shape of the insulator.