If the brake pedal in your car has gone soft over time or your brakes don’t feel as tight and immediate as they used to, you might need to bleed your brake fluid. The brake fluid in your car collects contaminants and degrades over time, losing its effectiveness. It’s important to flush it often to keep your pedal feeling like new.
Road & Track spoke with Kevin Hines, senior technician at McLaren Philadelphia, to learn the correct way to bleed your brakes efficiently and safely. Hines is North America’s only factory-certified McLaren F1 technician, which means his day job is working on $20 million exotics. If anyone understands how to flush brake fluid, it’s him.
Before reading any further, we suggest consulting your car’s owner’s manual for exact instructions on how to bleed brake fluid on your car. The manufacturer’s suggestions may differ from the instructions below.
Choosing Brake Fluid for Your Car
Before you get started on actually flushing your brakes, first confirm you have the right product for your car. “Make sure you use the right brake fluid,” Hines says. There are many different kinds of brake fluid, and your car’s braking system was designed to work with a specific type. “Get what’s applicable to your car or what’s already in the system,” he says.
Refer to your owner’s manual to see which type of fluid you should buy. In some instances, you can find this information printed on your brake fluid reservoir fill cap, located in the engine bay.
Having the Right Tools for the Job
At minimum, you’ll need a couple of basic tools to swap out your fluid. If you don’t have an automotive lift—and you likely don’t—you’ll need a couple of jackstands to get the car in the air so you can get the wheels off to access the bleed screws. Don’t cheap out on the jackstands!
Be sure to have a wrench to open and close the bleed screw on your calipers. Keep in mind the size of the screws may be different on front and rear calipers. You should also have a clear tube that can mount to the bleed screw going to a clear container to catch the old fluid. If you’re on a budget you can use an old water bottle. Alternatively, you can buy something made for the job:
“I like [the container] to be clear so I can see the color of the brake fluid,” Hines says. “That’ll tell you when you’ve got all the old stuff out. Usually brake fluid darkens as it gets older.”
How to Bleed Your Brakes
Before you start, Hines suggests taking a couple of seconds to feel out your brakes. “I would really recommend getting a feel for the brake pedal before you start,” he tells us. By doing this, you can check whether you’ve actually improved the feel of your brakes once you’re done.
After you’ve jacked the car in the air and removed the wheels, you can start bleeding your brakes. “Most of the time when I bleed brakes I’ll use a pressure bleeder,” Hines says. “Those can be had for pretty cheap. For F1s I’ll use the Motive Products pressure bleeder. It’s a handheld [unit] you can blow up.”
Having a pressure bleeder means you don’t need someone in the driver’s seat manually pumping the pedal to generate enough pressure to push out the old fluid. All you have to do is fill it with new fluid, connect it to your master cylinder, and pump it up with either a handheld lever or, if your bleeder has it, a compressed air connection.
If you’d rather not spend the money on a pressure bleeder for a simple brake fluid job, we understand. But if that’s the case, you’ll need another person to help, as the steps are a bit different.
If you’re not using a power bleeder, make sure to keep an eye on the fluid level in your brake master cylinder. As you bleed the brakes, fluid will come out, so you’ll have to periodically top it off. Forgetting to do this could introduce air into the system. And that’s bad.
Now, you can finally begin the bleeding process. “Always start at the caliper furthest away from the master cylinder,” Hines tells us. Going to the back of the car ensures the system will be fully flushed, with no potential for old fluid to be caught in the system. Hook up the tool you’re using to catch the fluid to the bleeder screw, then make sure there’s adequate pressure going to the brakes (either with the pressure bleeder primed or your buddy holding the brake pedal down). Then crack the bleeder screw. Fluid should come out immediately.
The bleeder screw is usually covered by a rubber grommet. Remove it before doing anything else.
When loosening the bleeder screw, try to be delicate. You don’t want to snap it off inside the caliper.
After fluid stops flowing, close the bleeder screw and either pump up the pressure bleeder or instruct your assistant to pump up the brake pedal. Crack open the screw again, and more fluid should come out. Repeat these steps until the fluid starts to come out clean. Once it does, you can move on to the next caliper.
We recommend going passenger-side rear ⇒ driver-side rear ⇒ passenger-side front ⇒ driver-side front. Once the fluid comes out clear on all four corners, congratulations, you’ve bled your brakes.
Some cars have brake calipers that feature more than one bleeder screw, one on the inside and another on the outside. “If you’re really doing a thorough job, and especially if you’re taking your car on the track, you’ll want to do the inside and the outside,” Hines says. Doing so will ensure all of the air and debris trapped in the system is removed properly.
Other Tips
“Don’t ever push on the brake pedal if you don’t have the brake pads installed and mounted on the rotor, because you’ll pop the pistons out,” Hines says.
This might seem obvious to some, but it’s still something you should keep in mind if you happen to be changing pads at the time. Pushing a brake piston fully out of its housing will cause a mess, and it’s not exactly easy to put back in.
“On cars that have sat for a really long time, I’ve seen a white paste form inside the system,” Hines adds. “It can be a bear to get out, because it’ll get inside the ABS block.”
This paste, Hines says, often can’t be removed through standard bleeding procedures alone, even if you use a pressure bleeder. If you encounter it, he recommends taking a sort of “Italian tune-up” approach.
“What I’ve done is do a brake flush, go out to a parking lot, and activate the ABS a bunch of times, jostle everything loose,” Hines says. “Then I come back, do another brake flush, and then do that for a whole day [repeatedly] and it clears everything out.”
Brian Silvestro
Former Lead Deputy Editor, Rankings Content
Brian Silvestro was Hearst Autos' former lead deputy editor for rankings content. He spent over seven years as a staff writer for Road & Track Magazine where he contributed car reviews, industry interviews, and more. He has a taste for high-mileage, rusted-out projects and amateur endurance racing.
