4 Simple Steps on How To Bleed Your Car Brakes
Does your brake pedal feel spongy? Has your car’s braking distance increased? Do you have to press more on the brake pedal than you previously had to?
If you are facing any of those problems, you need to bleed your brakes.
In this text, we’ll tell you how to bleed brakes by yourself and how to flush the brake fluid. Before we start with that, we need to establish a basic understanding of how your car’s brakes work.
DISCLAIMER: These are just some tips that can help you do minor repairs on your car. The actual results will depend on your understanding and execution of the steps. If you are not experienced in this type of work or think that you might not be able to do it the right way, get the help of a professional.
How Do Brakes Work?
The brakes on almost all modern street-legal road cars are hydraulic. They work by pushing a pressurized fluid.
When you press down the brake pedal, it creates pressure in the brake lines. That same pressure is taken to the brake calipers which in turn push the brake pads against the discs to slow the car down.
That’s an oversimplified explanation of how brakes work. Where does bleeding the brakes come in? Here’s what necessitates brake bleeding.
When Do You Need to Bleed Your Brakes?
The basic assumption on which the brakes of a car or any other hydraulic system work is that liquids cannot be compressed. If air enters the system, the balance is tipped. Air can be compressed.
Hence, if you have air in the brake lines and you push on the brake pedal, it will only compress the air in the system and very little or no force will reach the brake pads.
Here are the conditions when you need to bleed your brakes.
- If the brake pedal feels spongy and not firm.
- When it takes longer than usual for your car to stop.
- If you have a leak anywhere in the brake lines, you need to bleed them. Leaks don’t only let the fluid out but can also let air bubbles into the brake system.
- If your brake pads are worn out and you replace them. Braking with worn-out pads can lead to the master cylinder being drained and that can lead air into the system.
- If you brake too much for a long period of time like while descending a hill or during a race, the heat generated by braking can cause the brake fluid to boil. This can make the brakes less effective.
One thing must always be kept in mind.
Brakes are the single most important part of any car and you don’t want to take any chances with them. If you feel the slightest indication, bleed the brakes. It is also a good practice to bleed the brakes once a year as preventive maintenance.
We’ll now talk in detail about bleeding brakes by yourself so that you can do it at home.
How Do You Bleed Brakes by Draining Them?
The theory behind bleeding the brakes of your car is very simple. You need to make a hole in the lowest point of the brake line and let all the fluid out of the system. Let’s now see the actual brake bleeding sequence.
Step 1 – Locate the Bleed Valve/Screw
Luckily, car manufacturers provide a bleed valve/screw for bleeding the brakes. It is typically located at the bottom of the brake caliper assembly. You can find the exact location of the bleed valve in the owner’s manual or search on the internet.
Step 2 – Gather the things You Need
Once you have located the bleed valve, figure out what tool can be used to open it. These can usually be opened with a flathead screwdriver. You’ll need the following things for this process:
- A tool to open the bleed valve. It can be a screwdriver or a spanner.
- A catch pan to collect the brake fluid.
- New brake fluid as specified by the car manufacturer. Get a pressurized container if possible.
- A vacuum pump (optional)
Step 3 – Drain
This is the actual “brake bleeding” step. This is where you empty the brake lines to get any trapped air out. This can be done in a number of ways. Start with removing the cap of the master cylinder. Then undo the bleed valve/screw.
Now you can use one of the four following methods to expel the brake fluid from the brake lines.
- Gravity is the easiest and the simplest approach but it will take a bit of time. After opening the bleed valve, place the catch can below it and let gravity scoop all the brake fluid out of the system. This also makes a mess as the fluid comes out in an irregular way. Be prepared to clean everything once gravity has done its thing.
- Pressure can be used to speed up the process. You’ll need a pressurized brake fluid container for this. Attach the container to the master cylinder and it will force the fluid out of the lines. Once the fluid starts coming out in a constant stream and has no bubbles in it, you are done.
- The Brake Pedal can also be helpful. After you have opened the bleed valve, have a mate push the brake pedal repeatedly. The pressure created by the brake pedal will force the fluid out of the cylinder faster.
- A vacuum can also be used to speed things up when the bleeding brake lines. You’ll need a vacuum bleeder to do this. You can rent one at your local parts store.
Step 4 – Refill the Brake Fluid
Once all the liquid has been forced out of the brake lines, you need to refill the system for it to work right. Keep one thing in mind, you need to top the brake lines up with the brake fluid specified by the carmaker. Here’s how to fill it.
- Pour the liquid into the master cylinder and make sure it remains on the maximum level at all times.
- Once the brake fluid starts coming out of the bleed valve as a constant stream, push the brake pedal a few times while making sure the fluid level is at the maximum.
- Close the valve and you are done.
How Do You Bleed Brakes Without Draining Them?
You can also bleed the brakes without having to empty them. You’ll need a DIY brake bleed kit to do that. Here’s how this works.
- Get a DIY brake bleed kit for your car.
- Attach the plastic tube that comes with the kit to the bleed valve and place the other end of the tube in the master cylinder.
- Push the brake pedal repeatedly and the brake fluid will be circulated back to the master cylinder and the air will be removed.
- This method is the best if your brake fluid is new and you don’t want to waste it.
Cautions for Bleeding Brake Fluid
Bleeding the brakes is a fairly easy and simple process but there are some things that must be taken care of. If you want to do the whole thing right and do not want to get hurt during the process, follow these guidelines:
- Never work on the brakes just after you have come from a drive. The brake lines and the fluid in them can be very hot.
- Brake fluid can be carcinogenic. Always wear latex gloves when dealing with it.
- Don’t let the brake fluid come in contact with the brake pads or discs. It can cause lubrication and decrease the braking efficiency of the car.
- Always use the specified brake fluid for refilling the brake lines.
- If there is a leak in the brake lines you need to fix it before you can bleed and refill the brake lines.
- Never reuse the brake fluid.
When You Don’t Need to Bleed the Brakes?
There are a number of brake problems that can not be linked to air in the brake lines. These problems include the following:
- If the brake pedal is firm but the ABS is not working, the problem is with the ABS module and not the brake lines.
- If your brakes create noise, you need to get the rotors and pads fixed. This problem is caused by air in the brake lines.
- If your brakes don’t work right when you brake constantly, the problem is with the pads, not the brake lines.
- If the brakes tend to lock and the pedal does not return to the neutral position fast enough, it is not a bleeding-related issue.
- If your e-brake is not working right, the issue can most probably be with the e-brake cable and not the brake fluid or air in the lines.
Frequently Asked Questions
What is the correct brake bleeding sequence?
The correct sequence for bleeding car brakes is to open the bleed valve, expel the brake fluid using gravity, pressure, or vacuum, fill the system and then close the bleed valve.
How to get the air out of brake lines?
Bleed the brake lines and refill them to get the air out of the system.
Does a DIY brake bleeder actually work?
Yes, it does. You can use it to recycle the brake fluid and remove the air in it.
How long does it take to bleed brakes?
The whole process will take nothing more than an hour if all things go as planned.
When bleeding brakes should the car be on?
If you want to force the brake fluid out using the car’s brake pedal, the car needs to be on with the engine running. Otherwise, you can do it without having to start the engine.
Do you need to bleed brakes when changing pads?
Yes, you need to bleed the brakes after you have changed the brake pads.
Can you bleed ABS brakes?
Yes, you can totally bleed ABS brakes as the basic working principle is the same for them as for the other brakes.