故障现象部分装有PVC阀的大众车,当发动机暖车20 min左右,就开始发出类似振鸣、口哨的声音。在发动机室内随处都能听见,但在发动机下部靠后部位听起来尤为明显。抽出机油尺或打开机油加油口盖时该噪声会消失。故障诊断与排除当上述噪声出现时,没有机械振动的感觉。顺着异响声的来源查找,可以确定是曲轴后油封引起的。由于随着发动机温度升高,曲轴后油封刚度下降,不 Symptoms Part of the public car equipped with PVC valve, when the engine warm car about 20 min, it began to issue a similar vibration, whistle sound. It can be heard anywhere in the engine room, but the rear part of the engine sounded especially pronounced. This noise will disappear when you pull out the dipstick or open the oil filler cap. Troubleshooting and troubleshooting When the above noise appears, there is no feeling of mechanical vibration. Follow the source of abnormal sound search, it can be sure is caused by the oil seal after the crankshaft. As the engine temperature increases, the stiffness of the oil seal after the crankshaft decreases, no