ZJC2772819 | Genuine International® Power Brake Booster Cylinder

The booster multiplies the force from your foot, so you can stop the vehicle with minimal pressure on the brake pedal.

2. To improve braking performance

Because it increases force going to the master cylinder, the brakes respond faster and more powerfully, improving stopping distance.

3. To provide safer, more controlled braking

With assistance from the booster:

• Braking is smoother

• Easier to control

• More consistent, especially in emergency stops

4. To compensate for heavier vehicles

Bigger vehicles (SUVs, trucks, vans) need more braking force due to their weight.
The booster helps generate the high hydraulic pressure needed to stop them safely.

5. To reduce driver fatigue

Without a booster, you would need to press the brake pedal very hard, especially during:

• Stop-and-go traffic

• Long drives

• Heavy braking situations

The booster eliminates this strain.

1. Hard brake pedal

This is the most common symptom.
If the booster fails, you lose power assist, and the pedal becomes very stiff, requiring much more force to stop the vehicle.

2. Increased stopping distance

Because you must press the pedal harder and the brakes receive less hydraulic pressure, the vehicle takes longer to stop.

3. Hissing sound when pressing the brake pedal

A leaking vacuum booster often makes a hissing or air-escaping sound when you apply the brakes.

4. Brake pedal is slow to return

If the booster is damaged, the pedal may:

• Return slowly

• Feel spongy

• Stick partially down

5. Engine runs rough or stalls when braking

A vacuum leak inside the booster can affect the engine’s air/fuel mixture, causing:

• Rough idle

• Engine stumbling

• Stalling when you press the brakes

6. Brake pedal sinks or drops slowly

If the booster or its check valve fails, the pedal may:

• Sink when you hold it down

• Lose firmness
  (This can also indicate a master cylinder issue.)

7. Warning lights

You may see:

• Brake warning light

• ABS light
  If the booster fails and pressure is too low.