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The Importance of Fixing a Bad Brake Booster
A bad brake booster can be a serious problem. Braking performance can suffer and the vehicle’s ability to stop quickly and safely could be compromised. A failing brake booster can mean longer stopping distances, which increases the risk of an accident in certain situations. It’s also unpredictable, so you might not anticipate the increased stopping distance.
Common Signs of a Bad Brake Booster
If your brake booster is failing or it’s no longer functioning, it can affect your braking system as well as other systems. Signs can include:
- The brake pedal is harder to push than normal. Since the brake booster operates with vacuum, the degree to which the brakes are more difficult to apply can vary. Often, the first application can be almost normal while subsequent applications shortly after get progressively harder.
- It takes longer to stop your car. Since your braking power doesn’t have the necessary assistance from the booster, your stopping distance can increase.
- Engine stumbling or stalling. If there’s a massive vacuum leak in the booster, it could draw more boost than normal when you apply the brakes. It takes vacuum away from other components, and it can cause your engine to stumble, the RPMs to drop, and your engine could stall.
- The Check Engine Light can come on. Some cars are equipped with a brake booster vacuum sensor. If you have a leak, it can trigger the Check Engine light to come on.
- Whistling sounds. A vacuum leak at the booster can translate into a whistling or hissing sound, and it’s often worst when applying the brakes.
Steps for Diagnosing a Bad Brake Booster
If you have bad brake booster symptoms, there really isn’t any time to delay. A quick, accurate diagnosis can be the difference between confident commuting and an accident.
Many of the symptoms of a bad brake power booster can be shared with other faulty parts. Determining if it’s the booster, not something else, can be helped with these steps.
1. Spray for leaks
Mix dish soap and water in a spray bottle. With the engine running, mist the brake booster all over, paying special attention to the seams, the hose, the check valve, and any other joins. If there’s a leak, you can often see bubbles forming or water getting sucked in, identifying the source of the issue. You might also find that it’s the brake booster hose that’s collapsed or leaking rather than the brake booster itself.
2. Check for brake assist
From the driver’s seat, drive your car around the block, then park it. Run the engine for 30 seconds without touching the brake pedal, then shut it off. Immediately press the brake pedal and notice how many presses it takes before the pedal gets hard. A good brake booster should still provide some assist for the first three or so applications.
3. Test for boost on engine startup
Press the pedal several times until you can feel that it’s firm. That indicates that any vacuum in the booster has been discharged. With your foot on the brake pedal, fire up the engine. Notice if the pedal begins to get soft and drop under your foot. If it does, the brake power booster is likely not the culprit. But if it stays hard, then the booster could be bad.
4. Confirm that there’s vacuum
The symptoms could be indicating a bad brake booster, but it might be an issue of poor vacuum supply instead. With the engine off, remove the brake booster vacuum hose from the booster and fit a vacuum gauge to it. Start the engine, then watch for vacuum to build on the gauge. If it does, the booster is likely the issue, not the hose. If vacuum doesn’t increase, it could be a bad hose or, worse yet, an issue on the engine side.
Brake issues are always a safety concern, and a brake booster should be repaired immediately if it’s found to be the cause. Find your new brake booster at AutoZone today, with the right part for the job every time. If the job is too big for you, seek out one of our Preferred Shops to help you do the job.
FAQ/People Also Ask
How do I know if I need a new brake booster?
If you’re need more pressure to apply the brakes, it’s taking longer to come to a stop, the engine RPMs drop when you hit the brakes, or you hear a hissing noise when the pedal is applied, it could be a brake booster issue.
Will a bad brake booster cause a soft pedal?
On the contrary, a bad brake booster causes the pedal to get harder to press.
Can I drive with a bad brake booster?
Your brakes won’t function normally if your brake booster isn’t working at 100%. It’s not a good idea to drive until it’s fixed.
What does it sound like when your brake booster goes out?
You’ll often hear a whistling or hissing sound from under the hood whenever you apply the brakes.
Can you repair a brake booster?
If it’s a bad check valve or a leaking brake booster vacuum hose, the complete brake booster may not need to be replaced.
