目前的这个Stage I 阶段只是大致耳音识别的初级诊断，究竟是空调压缩机，发电机，张紧轮还是水泵轴承异常准备在Stage II使用Sethoscope也不排除暂时卸下发动机皮带排查再根据轻重缓急制定拆卸及配件方案。
Replacing your BMW's drive belts is routine maintenance that should be performed on a regular basis. We recommend replacing the accessory drive belts at 50,000 mile intervals. In addition to the accessory drive belts it will also be required at some point to replace the belt tensioners, hardware, and idler pulley. Most mechanical tensioners last between 60,000-75,000 miles and most idler pulleys do not last more than 100,000 miles. If your BMW is in the mileage range consider replacing all of your accessory drive components along with your belts and enjoy thousands of miles of trouble (and worry) free driving.