Does your brake pedal feel loose or hit the floor, even with a slight push?
That’s because you might have air in your brake system. And if you’re planning on getting it removed, you can try reverse brake bleeding.
This Article Contains
- How to Reverse Bleed Brakes
- 4 FAQs on Reverse Bleeding
Let’s get to it.
How to Reverse Bleed Brakes
Reverse brake bleeding or reverse flow bleeding is a brake bleeding method that removes air by injecting fresh fluid through the bleeder valve and out of the master cylinder reservoir (a.k.a the brake fluid reservoir).
While you can do it yourself, please seek an expert if you’re unfamiliar with automotive parts and repairs. Also, you should flush the old fluid first,especially if you have ABS brakes.
But first, let’s take a look at the tools you’ll need for reverse brake bleeding:
A. Tools and Equipment Needed
Here’s a list of equipment you’ll need to reverse bleed brakes:
- Floor jack
- Jack stands
- Lug wrench
- A reverse brake bleeder
- Several lengths of clear plastic tubing
- An 8mm wrench and hex bit sockets
- A syringe or a turkey baster
- Fresh brake fluid
Note: Consult your owner’s manual to find the correct type of brake fluid your vehicle needs. Using the wrong fluid can reduce braking power and damage your brake system (brake pads, caliper, etc.), and don’t reuse old brake fluid.
Reusing old fluid can completely wreck your hydraulic system and lead to costly repairs.
Now, let’s see how it’s done.
B. How It’s Done (Step-by-step)
Here’s what a mechanic would do to reverse bleed your brakes:
Step 1: Jack up the vehicle and remove all wheels
First, park your car on a flat surface and release the brake lever.
Then, jack up your vehicle, remove all the wheels to expose the wheel cylinder, and inspect the brake line for leaks.
Step 2: Identify the correct bleeding sequence and find the bleeder nipple
Identify the proper bleeding sequence of your vehicle. For most cars, it starts from the brake farthest away from the brake fluid reservoir, which is the rear brake on the passenger side.
Also, locate the bleeder nipple (also known as bleeder screws or a bleeder valve) behind the brake caliper. Most vehicles have one bleed nipple per brake, but certain sports cars may have up to three for each brake.
Step 3: Locate the master cylinder and remove a small amount of fluid
Next, open the master cylinder and remove some brake fluid using a syringe. This prevents the brake fluid from overflowing.
Step 4: Assemble the reverse brake bleeder kit
Once done, assemble and prime the brake bleeder kit by running fresh brake fluid through the bleeder pump, hose, and container. This helps to detect any leaks in the brake bleeder parts.
Step 5: Connect the tool to the bleed port
Now, connect the hose to the bleed port. Use an adapter to fit the hose tightly to the bleed nipple if needed.
Optional: Apply a few rounds of Teflon tape onto the valve threads to prevent the hydraulic fluid from leaking onto the brake components.
Step 6: Loosen the bleed screw and pump in the new fluid
Next, loosen the bleed screw and slowly pump the lever 6-8 times to let the new fluid into the bleeder valve. Pumping slowly and steadily prevents the fluid in the brake fluid reservoir from spouting like a fountain.
Also, keep an eye on the reservoir to prevent overflowing. If the brake fluid level rises, remove a small amount of fluid with a syringe.
Step 7: Remove the connector from the bleed valve
After a few minutes, release the hose from the bleed valve and leave it open for a few seconds to burp out any air bubbles from the valve.
Once done, close the bleeder screw and make sure it’s tight.
Step 8: Repeat steps 3-7 on the other remaining wheel cylinder
Repeat steps 3 to 7 on the remaining brakes.
For step 6, instead of pumping the bleeder lever 6-8 times, pump it 5-6 times per brake. That’s because as the distance between the brake and the reservoir gets shorter, less pressure is needed to push out the air bubbles in the brake line.
When all the brakes are done, check the fluid level in the master cylinder reservoir and close it.
Step 9: Observe the brake pedal
Finally, check the brake pedal. If the pedal is firm and doesn’t hit the floor at a slight push, then the reverse flow bleeding is successful.
Next, let’s answer some FAQs to understand reverse bleeding better.
4 FAQs on Reverse Bleeding
Here are the answers to some commonly asked questions on reverse brake bleeding
1. What’s the Difference Between Reverse Flow Bleeding and Other Methods?
The most obvious difference is the flow of fluid. Most bleeding methods direct the fluid out of the master cylinder through the bleeder valve.
In reverse flow bleeding, brake fluid flows in the opposite direction. This method takes advantage of the physics theory — air rises in fluids. Instead of forcing the trapped air to stream down the bleeder valve, it’s pushed up and out of the master cylinder reservoir.
2. What Are the Pros and Cons of Reverse Bleeding?
Like any other method, reverse bleeding brakes have their own pros and cons.
Some advantages of reverse bleeding are:
- Can be carried out alone
- Takes less time and effort to remove trapped air
- Works well on vehicles with ABS
Here are some disadvantages of reverse bleeding:
- The brake system needs to be flushed to remove old fluid
- Brake fluid might overflow in the reservoir
To get the most out of reverse bleeding, please follow the steps correctly, or you can get help from an expert.
3. Does Reverse Bleeding Work on ABS?
Yes, it does.
The brake bleeding process is similar to how you’d bleed brakes in non-ABS vehicles, but you’ll need additional steps and tools to reverse bleed ABS brakes.
For example, you’ll have to do a brake flush before you bleed the brakes. This prevents debris and gunk in the old brake fluid from getting stuck inside the ABS lines.
You’ll also need an ABS Scan Tool to unlock hidden valves or passages and control the motor pump when you bleed the brakes. This ensures that fresh fluid runs through the ABS unit.
4. How Often Should I Bleed My Car Brakes?
Typically brake bleeding is done every two to three years and shouldn’t be carried out too often.
However, brake bleeding is also performed after every brake system repair (installing new brake pads, brake caliper replacement, etc.) or when you have a spongy brake.
Reverse bleeding brakes is a simple and effective method to remove air from the brake system. It takes less time and effort compared to conventional brake bleeding.
You can follow our steps, but when in doubt, always consult a professional — like Repairsmith!
RepairSmith is a mobile automotive repair and maintenance service you can get by booking online. Our technicians are well-trained and equipped with the tools needed to complete the job.
Contact Repairsmith today if you need a brake bleeding service, and we’ll send our best mechanics to your driveway!