A brake booster vacuum pump is a component found on the braking system of many modern diesel vehicles equipped with diesel engines. Due to their operational nature, diesel engines generate considerably less manifold vacuum than gasoline engines, and as a result, require a separate pump to produce the vacuum required for the booster to operate. It is responsible for generating vacuum for the vehicle’s brake booster so that the power assisted braking will work.
As the vacuum pump is what allows the vehicle to have power assisted braking, it is a very important component to the overall safety and handling characteristics of the vehicle. When the pump does fail or begins to have problems, usually a few symptoms will be produced that can alert the driver that a potential problem has occurred and should be serviced.
Stiff brake pedal
One of the first symptoms of a potential problem with the brake booster vacuum pump is a stiff brake pedal. The brake booster vacuum pump supplies the vacuum required for the power brake booster to work. If it fails or has a problem, the vehicle will be left without assisted braking. Without the brake booster, the brake pedal will be stiff and will require considerably more effort to stop the vehicle.
Intermittent power brakes
Another less common symptom of a problem with the booster vacuum pump are power brakes that function intermittently. As most brake booster vacuum pumps are electric, if there is any problem with any of the wiring or internal components, this may cause the pump to come on and off intermittently. Most pumps are designed to run continuously to provide a constant supply of vacuum so that the power brakes will work at all times. If you find that the brakes are assisted some times and not others, then the pump may not be functioning correctly.
The brake booster vacuum pump is an important piece of the power brake system, as the power brakes cannot function without the vacuum it supplies. For this reason, if you suspect that your brake booster vacuum pump may be failing, have the vehicle’s brake system diagnosed by a professional technician, such as one from YourMechanic. They will be able to determine if the car needs a brake booster vacuum pump replacement, or make any other repairs if needed.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Brake Booster Vacuum Pump and was authored by Ed Ruelas.