Here’s something no car owner wants to experience:
You press down on your pedal, and it feels like you’re pushing a ton of bricks. Additionally, your car no longer slows down as quickly as it used to, making braking a nerve-wracking experience.
Clearly, this is an issue your mechanic needs to take a look at.
And it’s likely to do with your brake booster.
But how do you tell when you need a brake booster replacement?
And what’s the best way to get it fixed?
In this article, we’ll go over how to detect a failing brake booster. We’ll look at all the questions you might have when you need a booster replacement and even highlight an easy replacement solution.
In This Article:
(Click on a link below to jump to a particular section)
- What The Brake Booster Does
- Identifying A Bad Brake Booster
- Brake Booster Replacement: 8 Things You Should Know
- Can I Test The Brake Booster?
- How Urgent Is A Brake Booster Replacement?
- Can I Still Drive With A Bad Brake Booster?
- Is A Bad Brake Booster An Isolated Problem?
- What Are The Benefits Of A Brake Booster Replacement?
- Can I Replace A Brake Booster On My Own?
- What Happens During A Brake Booster Replacement?
- How Much Does A Brake Booster Replacement Cost?
- The Easiest Solution To Brake Booster Replacements
But first, let’s take a quick look at what the power brake booster is and does:
What The Brake Booster Does
When you press the brake pedal, the power brake booster amplifies that force, driving it to the brake master cylinder and brake calipers. The brake calipers then press against the brake pads, which squeeze the brake rotors to slow the car.
That’s how a “tap” of your foot stops the movement of a 4000 lb car!
While it isn’t the only amplifying factor at work in the entire brake system, the power brake booster plays an essential role in making it easier for you to press the brake pedal.
You’ll usually find three types of brake boosters:
- Vacuum boosters are the most common. These utilize the engine vacuum from the engine manifold (or from a vacuum pump) to boost the vehicle’s braking ability.
A check valve ensures no unwanted air is trapped in the vacuum booster. This air could end up in the brake fluid and reduce the hydraulic pressure in the brake lines, reducing your brake’s effectiveness.
- Hydraulic boosters use hydraulic pressure from the power steering pump instead of a vacuum pump.
- Electro-hydraulic boosters typically use a hydraulic pump and an accumulator assembly.
Since the vacuum booster is the most widely used type, here’s a quick breakdown of what happens in a vacuum brake booster:
- The booster has two chambers separated by a disc-like diaphragm.
- When the engine is running, a vacuum is applied to both of these booster chambers from the vehicle’s intake manifold.
- The driver depresses the brake pedal, triggering a valve that lets the outside air enter — creating atmospheric pressure on one side of the booster.
- The pressure differential between the two sides amplifies the force from the brake pedal as it drives the pushrod into the master cylinder — generating a power-assist.
- When the driver releases the pedal, the vacuum returns to both sides of the booster.
Now that you know what brake boosters are and how they work, let’s go over what happens when something’s wrong:
How To Identify A Faulty Brake Booster
Here are some common signs of a failing power brake booster:
1. A Hard Brake Pedal
A functioning brake booster results in an easy-to-press brake pedal.
With a faulty power brake booster, you’ll likely lose all the power-assist that you’d usually have, resulting in a stiff brake pedal that’s hard to press.
If your vehicle is dependent on a vacuum pump or uses a hydro booster with a power steering pump — then one of these pumps could be failing.
2. A High Brake Pedal
You might also notice that the brake pedal is positioned higher than usual, requiring you to lift your foot higher to press down on it.
This is another tell-tale sign that something’s wrong with your braking system, and it could be an issue with your brake booster.
3. Lower Braking Power
This is the easiest issue to notice.
When you depress the brake pedal and find that your car doesn’t slow down as quickly as it used to, something’s wrong.
And as your brake booster is directly responsible for amplifying brake force, it isn’t doing its job, and something is wrong.
4. Fluid Leaks
Fluid leaks of any kind from your vehicle indicate some sort of problem.
The most common of these problems is hydraulic brake fluid leaking from a damaged power brake booster or master cylinder.
A master cylinder fluid leak happens if the brake master cylinder is leaking from the rear. In this case, your mechanic may remove the master cylinder from the engine compartment and have a look.
Brake fluid in the booster can damage the booster diaphragm. Not only that, a brake fluid leak will reduce hydraulic pressure in brake lines and possibly introduce air into the brake fluid, reducing pressure even further.
Sometimes, there aren’t any external signs of this type of fluid leak, and one way to figure this out is to have your mechanic run a clean engine dipstick through the booster vacuum check valve. If there’s brake fluid on the engine dipstick, then there’s definitely a brake fluid leak.
5. Reduced Engine Function
A puncture in the power brake booster diaphragm introduces a vacuum leak that can draw air into the induction system, affecting your engine’s fuel mix. Your engine RPM might drop, and it may feel like your engine stalls each time you press the brake pedal.
This particular problem could lead to more than just bad brakes — it can also cause costly engine problems. A vacuum leak can also be due to other issues like a cracked vacuum line.
6. Your Warning Lights Start Flashing
Brake booster issues can trigger the ABS or traction control lights to turn on. Sometimes, even the Check Engine warning lights might come on as a result of booster issues.
For example, if the booster diaphragm is leaking and allows unmetered air to be drawn in — the oxygen sensors will detect the lean fuel mixture and trigger the Check Engine light.
If you face any of these faulty booster symptoms, it’s always a good idea to take your car to a mechanic, as you’ll likely need a brake booster replacement.
Brake Booster Replacement: 8 Things You Should Know
Here are answers to some questions you might have when dealing with a bad brake booster.
1. Can I Test The Brake Booster?
You can perform a simple test to see if your vacuum brake booster is working.
- With the engine off, pump the brake pedal about six times. Doing this removes any vacuum stored in the booster.
- Now, apply light pressure to the brake pedal and turn on your vehicle.
If the pedal gives slightly under your foot and then firms up, the brake booster is fine.
If the pedal stiffens and has trouble dropping, the brake booster is likely failing.
2. How Urgent Is A Brake Booster Replacement?
A bad brake booster is something that needs fixing ASAP.
Additionally, driving with a brake problem is never a great idea, so don’t drive to the mechanic, but call one to come to you instead.
3. Can I Still Drive With A Bad Brake Booster?
The quick answer is — yes.
You’re able to drive with a bad brake booster as there’s still a mechanical connection within the booster via the booster rod, even if there’s no power-assist.
If everything else is fine, then your master cylinder will still pump brake fluid through the brake lines to get the brakes to engage.
However, is driving without a brake booster recommended?
You’d have to apply far more pressure to stop the car. Without a power brake booster, you’d have to depress the brake pedal quite hard just to slow down even a bit.
Because theoretically, you’re now fighting the inertia of that heavy car almost 1:1 — that’s 4000 lbs of steel versus your foot strength!
4. Is A Bad Brake Booster An Isolated Problem?
Sometimes, brake booster problems can be an isolated issue that’s resolvable with a simple brake booster repair. Alternatively, it could be a faulty check valve along with a booster vacuum hose issue. This would likely just need a hose or valve replacement.
However, if the brake booster problem has been going on for a while, other components of the brake system could be affected.
Your brake pads might need replacement, and even the tires or other connected vehicle parts could have incurred damage due to a faulty brake booster.
5. What Are The Benefits Of A Brake Booster Replacement?
On top of the obvious benefit of easier braking, you’ll have better control of your car. You can slow down quickly and take smoother corners.
You could also have better fuel economy.
Braking also uses up a lot of fuel, and inconsistent braking (because of a faulty booster) will create poor fuel mileage.
6. Can I Replace A Brake Booster On My Own?
If you’re not a qualified mechanic, it’s not recommended that you tackle this replacement on your own.
You’d have to make sure the booster is fixed properly to the bracket on the firewall, linked to the master cylinder, deal with the vacuum line and intake manifold, and ensure every bolt and hose clamp is secured…
And that’s not even half of it during a booster removal and replacement!
The braking system is not something you can afford to fix on your own to save some money. There’s no margin for error, and a tiny mistake could cost far more than you’re prepared to pay.
Always take your vehicle to a reputable mechanic instead.
7. What Happens During A Brake Booster Replacement?
While you won’t be doing this on your own, it’s good to know what kind of work your mechanic will perform during a brake booster replacement.
Here’s what your mechanic will do during a vacuum brake booster removal and installation:
- They’ll diagnose the brake booster problem based on the type of braking system your vehicle has. This is when the check valve will likely get a look-over along with any other booster-related valve.
- Then, they’ll take out the master cylinder and detach the hydraulic brake lines. Sometimes, the brake lines are long enough to remain attached to the master cylinder. In some cases, the battery and battery tray might need to be taken out of the engine compartment, too.
- Next is removing the vacuum hose clamp with pliers and detaching the brake booster vacuum supply hose.
- Now, they’ll disconnect the booster pushrod from the brake pedal and remove the faulty brake booster from its bracket on the firewall.
- Then, they’ll install a new brake booster and reattach the booster rod, vacuum hose, and all the other necessary parts. Make sure each bolt is tightened down.
- Finally, they’ll test the brakes to ensure everything is connected and working correctly and run a road test to evaluate how the vehicle performs with the new brake booster unit.
8. How Much Does A Brake Booster Replacement Cost?
The average cost for a brake booster replacement could fall anywhere between $325-$1250.
Labor costs usually range between $100-$200, and vehicle parts can be as low as $100 or as high as $900 (or more). The cost is largely driven by the make and model of your vehicle and the mechanic’s labor rates.
Here are some samples to give you an idea:
|$108 – $138
|$258 – $576
|$366 – $714
|$81 – $103
|$138 – $282
|$219 – $385
|$360 – $459
|$186 – $265
|$546 – $724
|$216 – $275
|$315 – $617
|$531 – $892
|$270 – $344
|$127 – $141
|$397 – $485
|$243 – $310
|$176 – $956
|$419 – $1266
|$252 – $321
|$328 – $676
|$580 – $997
Next up, how do you find a responsible mechanic?
The Easiest Solution To Brake Booster Replacements
Looking for a reliable professional to deal with your brake booster repair can be troublesome.
You’ll want someone who’s transparent about all the necessary repairs needed, especially if it involves more than just replacing the power brake booster.
When looking for a mechanic, be certain that that they:
- Are certified
- Use only high-quality replacement parts and tools
- Offer a service warranty
To make sure all these boxes are checked off, look no further than AutoNation Mobile Service.
AutoNation Mobile Service is a convenient mobile car repair and maintenance solution that offers you these benefits:
- Online booking is convenient and easy
- Brake booster replacements can be done right in your driveway
- Competitive, upfront pricing
- Expert technicians perform the repairs
- All repairs and maintenance are executed with high-quality equipment and replacement parts
- AutoNation Mobile Service provides a 12-month | 12,000-mile service warranty for all repairs
To get an accurate estimate of how much your power brake booster replacement will cost, just fill this online form.
Boost Your Brake Pedal
The brake booster is an important component responsible for delivering a comfortable and safe driving experience for you. Keep an eye out for any of the symptoms we mentioned, as a faulty brake booster is something you need to address ASAP.
And if you’re looking for a trustworthy mechanic, AutoNation Mobile Service is just a few clicks away. They’ll handle all of your brake problems right in your driveway.