If you’re not a mechanic, you may have never heard of a brake booster. But the truth is that your car almost certainly has a brake booster, and if it fails, you will feel it.
Read on to learn the common signs of a brake booster failure, the cost to replace it, and how to test the brake booster properly.
What is a Brake Booster?
Brake boosters, like your power steering, help you press down on the brakes easily by amplifying the force you apply to the brake calipers or drums. The result is that your brakes respond to a fraction of the force you’d normally need to stop on a dime.
There are various styles of brake boosters, but they function the same way.
Symptoms of a Bad Brake Booster
There are a few blatant symptoms that indicate a bad brake booster, and they should not be difficult to diagnose. Even if you can’t tell the difference between a lug nut and a spark plug, you should be able to determine the issues after reading these symptoms!
#1. Hard Brake Pedal.
If your brake booster fails, the first thing you’ll probably notice is that it will be hard to press the brake pedal down or that it has a spongy feel to it.
It only makes sense. The entire point of the brake booster is to take away from the effort it takes to press down the brakes. If it fails, then it is going to take a lot more effort on your part.
#2. Increased Stopping Distance and Leaking Brake Fluid.
Increased stopping distance is not a direct symptom of your brake booster failing, but it is a sign that the brakes should be inspected a little more.
The big deal is if your brake booster is leaking, your brakes aren’t working properly. The best thing you can do if you notice the stopping distance is increasing in your vehicle is to inspect the brake booster for a leak.
It will be difficult to identify the leak if you catch it between the brake booster and the master cylinder. This is nearly impossible to do, and that is why many mechanics will change both aspects when changing one or the other.
#3. Hissing Noises.
If your brake booster is vacuum operated, you may hear a hissing noise when you depress the brakes. This indicates that your brake booster has a vacuum leak, which will not allow it to function properly.
#4. Warning lights illuminated.
Depending on the type of vehicle you are driving and what safety features are in place, you may see a variety of different lights illuminate on your dashboard if you have a bad brake booster.
Typically, the most common light would be the ABS light, however, you may see a traction control light, a check engine light, and stability control lights also come on.
Can You Drive With a Defective Brake Booster?
Yes, but it’s not a great idea.
If your brake booster is inoperative, it may not be a great problem, as many vehicles do not have a brake booster. You can keep on driving, only you’ll have to push down harder on your brake pedal when you want to stop.
However, everything depends on what’s wrong with your brake booster. One thing you should never do is drive your car with a leaking brake booster. Brake fluid leaking from your brake booster into your car’s engine will reduce your braking performance, which is a big deal.
Furthermore, you can go from a leak to a flood in a hurry, and you may not even be able to use your brakes at all. Additionally, if a situation arises when you need to stop instantly, the last thing you want to be worried about is whether you can push down hard enough on the brake pedal.
So to answer your question: yes, you can drive with a faulty brake booster, but we wouldn’t recommend it.
Brake Booster Replacement Costs
Having your brake booster replaced is not a cheap service. Parts and labor will typically run somewhere between $500-$800 in total for you to get back on the road.
These costs will vary depending on where you take your vehicle to be serviced and the type of vehicle you drive.
If you go the DIY route, you will typically pay about $100-$150 for a new brake booster; however, if you have a full-size truck or SUV, you can spend $300 and up.
In addition, you will need to purchase new brake fluid and bleed your brakes –this is another $20-$40 in parts.
While most mechanics are happy to bleed your brakes, the labor for this service is typically $300-$400 for them to replace your brake booster. However, being they will need to bleed your brakes as well, add roughly $75-$100 to that price estimate.
If your brake booster is leaking from the check valve, you may have some luck ordering just a check valve and grommet kit. You can usually get these kits for less than 10 dollars, however, brake fluid will need to be replaced as well.
How to Test a Brake Booster
You can use two simple tests to figure out if your brake booster is functioning properly.
Test #1
The first test checks to see if the brake booster is assisting with your braking pressure as it should.
- With the engine off, pump your brakes by depressing the brake pedal a few times until the pedal becomes stiff.
- Once the pedal is stiff, keep your foot on the brake while you start up the engine.
- The brake pedal should continue to depress a little more after starting the engine. If it does, the brake booster is working properly.
- If the vehicle fails this first test, the brake booster is faulty.
Test #2
- To perform the second test, start the engine and depress the brake pedal.
- While keeping the brake pedal depressed, turn off the engine.
- If the brake pedal does not drop in the time frame of 20 to 45 seconds, the brake system is airtight (including the brake booster).
- If the brake pedal dropped to the floorboard, that doesn’t mean that the brake booster itself is the problem.
- Before concluding that your brake booster is the problem, you need to rule out any potential leaks in the brake system.