Mechanical Vacuum Pump by Dorman®. 1 Piece. Dorman Vacuum Pumps are 100% new, not remanufactured. Since they are new, they do not contain any used components that could lead to premature failure. Most premature failures occur with the bearing. A bearing failure will prevent the pump from producing vacuum. Depending on the vehicle, this may result in a loss of vent or temperature control inside the cabin, impaired or partial loss of braking or 4WD. Dorman has re-engineered the original needle bearing on the CAM which seizes, causing pump failure.