For diesel engine vehicles, the internal structure and strength of the vacuum pump is improper, and therefore, the vanes inside the pump and/or the pump housing may break. If this occurs, (1) no negative pressure can be generated causing the vacuum brake booster to stop functioning, in which case braking efficiency will be reduced, and/or (2) the engine oil inside the vacuum pump can leak causing the engine to lack lubrication, in which case the engine could stop and will not restart.