What is a Brake Power Booster Unit Check Valve?
The power booster unit check valve is a component of the power brake system in a car, truck, or SUV. It makes sure that vacuum is consistently applied to the brake power booster and helps to maintain power assist momentarily should the vehicle lose engine power. The power booster and check valve are located near the brake master cylinder and fluid reservoir in the engine compartment.
How does a Brake Power Booster Unit Check Valve work?
To help a driver slow and stop a moving vehicle, the brake power booster provides a vacuum "assist" to the brake pedal. This vacuum assist essentially multiplies the force of the brake pedal as pressure is applied during braking. Braking is made possible with less effort from the driver. The power booster check valve allows vacuum created by the engine to suck air out of the power booster, while preventing air from entering. This allows the vacuum in the booster to remain consistent. The check valve also serves to maintain vacuum momentarily in the booster if the engine stalls, giving the driver an initial power assist before the brake system reverts from power braking to manual braking.
What are the symptoms of a bad Brake Power Booster Unit Check Valve?
The primary symptom of a faulty power booster check valve is a brake pedal that is hard to press. If the check valve is not working properly or it is leaking, the power booster will not be able to hold a vacuum. As a result, the power assist to the braking system will diminish.
Can I drive with a bad Brake Power Booster Unit Check Valve?
The brake power booster check valve is a simple component, but it is an important safety feature of a vehicle. Without a working check valve, the power booster will not operate properly and the brakes will be very hard to push. The larger the vehicle, the more difficult it is to stop, and the more the power assist is necessary. While the brakes will work manually (without power assist), they will be very difficult to operate - especially at higher speeds. The vehicle should not be driven with a faulty check valve. If the check valve fails completely during driving, and the engine stalls, power assist will cease immediately and without warning. If the brake pedal is becoming hard to press, the vehicle should be inspected as soon as possible for a faulty check valve or failing power booster.