Bleeding Brakes: How to Bleed a Brake Line in Your Car?


Bleeding brakes? Do you have any idea about it? The braking system of your vehicle is one of the most critical components as far as your vehicle is concerned. Regardless of how fast you are going, you need to be able to stop on demand, no matter how fast you are going.

A vehicle’s braking system uses hydraulics, which means that pressurized fluid is pushed by a pump to brake the vehicle. There will be less pressure in the system if there is an air bubble in it and the brakes will feel spongy and you will need to stop for a longer period of time.

There are ways to fix this, but there is also a way to prevent it from happening in the first place.

Why Does a Brake of a Car Get Spongy?

In order to get air into your braking system, there are several different ways to do so, and all of them involve brake fluid in some way.

There is a hydraulic system that controls your brakes, which means fluid is responsible for making your brakes work. Your car’s brakes are located at the four corners of the car; when you press the brake pedal, brake fluid is pushed out to those brakes.

bleeding brakes how bleed brake line your car
Bleeding brakes how to bleed brake line your car

The friction generated by the brake pads in a disc brake is what moves them inward to clamp down on the brake rotor and slow the car by using the force of the fluid pushing into the brake caliper.

What is the Actual Meaning of Bleeding Brakes?

Brake bleeding is the process of removing any air bubbles that might be present in the brake lines that are connected to the hydraulic brake system so that the brake fluid can be circulated.

The reason for this is that, while brake fluid is an incompressible liquid, air bubbles in the brake system are compatible gases, and their presence greatly reduces the hydraulic pressure that is capable of developing within the brake system due to the fact that air bubbles are compressible gases.

This method ensures that the air particles trapped inside the brake line(tube) are pumped out in a way that ensures that the line is completely filled with fluid and that the line is pumped out completely.

As the fluid is poured into the line, the pressure within the system is continuously increasing, and then all of a sudden the calipers’ bleed valve is suddenly opened, thus the fluid that gets pumped out also brings trapped air bubbles with it, and this process continues until the desired retraction and stiffness is achieved.

Need for brake fluid and its co-relation with bleeding brakes

It is the brake fluid, which is considered the heart of the brake system and is responsible for ensuring that it works properly for several years before it needs to be changed.

The brake fluid that is used in vehicles loses its moisture resistance over time and starts to absorb small amounts of water, which not only reduces the brake system’s performance but can also corrode key parts of the system over time.

In addition to ensuring that you’re motoring in a safe vehicle when you replace the brake fluid at recommended intervals, it can also help you avoid having to pay for expensive brake repairs in the future as well.

Bleeding the brake system is an essential part of the brake fluid replacement process. As a result of this procedure, you are simply removing the trapped air from the brake system, as well as some old brake fluid that is no longer needed.

What is break flushing?

Similarly to bleeding your brakes, you must also flush or purge your brakes, where an old contaminated fluid is replaced with new contaminated fluid, which is a necessary part of your brake maintenance process.

Can you distinguish between brake flushing and brake bleeding?

During the course of learning about brake flushing, many drivers will encounter the concept of brake bleeding as part of their education about brake flushing. A partial flush is being performed here in order to help release air from the braking system, so this is somewhat of a partial flush.

  • When the brakes are bled, some of the brake fluid is released until the technician is sure he has removed all of the air bubbles from the system.
  • When it comes to a flush, a flush is the complete removal of the brake fluid from your vehicle’s system, on the other hand. It is important to note that brake bleeding is primarily used for tuning purposes, while brake flushing is more based on general maintenance.
  • According to general consensus, it is more recommended to flush the brakes than to bleed them. In the event you feel that your brakes have a spongey feeling, you should avoid bleeding or flushing your brakes on your own if you feel that they feel spongey.

What is the need and importance of brake bleeding?

A brake bleeding job is a general repair job that many people would not like to do, but it is something that an automobile needs to be done throughout its lifetime in order to prevent serious problems.

The brakes of most cars need to be bled every two to three years in order to maintain the optimum performance of the brake system. When you step on the brake pedal, small amounts of air may be trapped in the brake line, resulting in a spongy feel when you step on the brake pedal.

There is a possibility that your vehicle will suffer a complete failure of braking if large amounts of air enter the brake line.

How does air get in the brake system?

There is a possibility that air can enter your brake system during some types of servicing or if there is a leak in your brake system. The air can also enter the line for less obvious reasons, such as worn pads or a driver who is impatient and continually slams on the brakes. This can cause the line to be clogged with air.

The purpose of bleeding brakes is to remove the air from the brake line so the brakes will work properly. The purpose of this is to make sure that your brakes are in top condition. This will ensure that you would not be driving off the edge of a cliff like some tragic characters in movies seem to do.

Methods of bleeding car brakes

Generally, there are five main methods of bleeding a car brake, they are as follows:

The Vacuum Method

In this method, the bleeder valve is attached to a vacuum pump, and once the valve is opened, the fluid is extracted through the pump until the air bubbles have disappeared.

The Pressure Method

A pressure pump is connected to the master cylinder which pressurizes it. The bleeder valves are then opened one by one until all air is removed from the hydraulic fluid, and the pressure pump is removed from the master cylinder. A brake fluid reservoir may be kept fully topped up during bleeding by using a method that is incorporated into special pumps.

The Gravity Bleeding Method

There is an easy and convenient way to replace automotive brake fluid with gravity bleeding. It can also be used in situations where air bubbles are present in a system, but may not be as effective as other methods of bleeding systems

The Reverse Method

In order to force fluid through the bleeder valve and into the master cylinder, a pump is used. As air rises in liquids, this method is based on the concept that the water vapor will naturally rise and escape up and through the brake system.

The Pump and Hold Method

The brake pedal is pressed as this method allows the air to escape while each bleed screw is opened one at a time, allowing the air to escape one by one. There must be a one-way valve installed in the pedal unit, or the bleed screw must be closed before releasing the pedal.

What are the resources needed for bleeding brakes?

Before the start of the process of bleeding breaks, there is a need for a few tools and resources. The tools that are usually needed are as follows

  • An adjustable box-end wrench for bleeder screws on your car. It is usually best to use an offset head design
  • A can of good-quality brake fluid
  • A car jack tool
  • A bottle that can be disposed
  • Some brake cleaners of nice quality that will be used for the cleaning of the parts before resealing them.
  • Someone to hold, pump the pedals of the brake, and assist you with the process

Some safety precautions to keep in mind before starting the brake bleeding process

  • It is always recommended that latex gloves be worn when working with brake fluid because it could be carcinogenic and has the potential to cause cancer.
  • It is always a wise idea not to work on the brakes immediately after a drive. As a result of the brake fluid and the brake lines being heated up, the brake fluid can become very hot.
  • You should clean up any spills as soon as possible because brake fluid can eat away at the paint of your vehicle.
  • It is important not to let your brake fluid come in contact with the brake pads or brake rotors of your vehicle. The brake pads can be lubricated by it, and the effectiveness of the brakes can be reduced.
  • The brake fluid should never be reused if it has been used previously. Depending on the quality of your brake fluid, it may contain impurities that can damage the critical parts of your brake system.
  • The first thing you should do if you notice a brake line leak is to ask a mechanic to repair it.

The process of bleeding the brakes of a car

 Using these steps, you can bleed your brakes in no time at all

  • The type of brake fluid that is required for your particular vehicle can be found in the owner’s manual. The manufacturer of your car will also tell you at what intervals you need to replace the brake fluid. There are several different types of brake fluid, and they do not mix well together.
  • Before you begin working on your brakes, it is very important that you pick up the correct brake fluid from an auto parts store or the parts department of your dealer. There are two or three 12-ounce cans of good-quality brake fluid that you will probably need to bleed the brake system, depending on the size of your vehicle.
  • If you have a jack stand, you will need to position it at the jacking points shown in your owner’s manual on level, solid ground, and support your vehicle with four jack stands placed at these points. As far as property values go, you can prop it up on cinder blocks if you want your neighbors to start getting nervous about their property values.
  • However, it needs to be on solid footing while up in the air; at times you may end up crawling under the car as you go about bleeding the brakes. It is necessary to remove all four wheels from the vehicle.
  • You will need to locate each of the four bleeding screws for your caliper, one of which can be seen in the illustration above in a typical location. It is also possible to find bleeder screws on drum brakes.
  • If you are unable to loosen them gently, you might have to use all of your strength to twist them. In the case that they are difficult to loosen, spray them with penetrating oil, let them soak in for about a half-hour, and then try to do it again. As soon as they snap or strip, take your vehicle to a shop as soon as possible so that a professional can take care of the problem.
  • In order to force the brakes to bleed, you will need to loosen the bleed screws one at a time; you will be bleeding each brake separately, and the other screws will need to be closed so that the engine does not get sucked in with air. You should avoid air bubbles in your brake system at all costs; they can make your brake pedal feel mushy and reduce the performance of your brakes.
  • The brake master cylinder reservoir fluid level should be checked when the hood is raised and the master cylinder is removed. If you have an owner’s manual, you will probably be able to find out where it is located.
  • If the level of the clear reservoir is lower than the marked full line, you will need to add fresh fluid. You need to make sure that the fluid you are using for your vehicle is the right one. The master-cylinder cap should be left unscrewed during brake bleeding, but it should remain in place atop the reservoir, although it should not be tightened. The correct sequence must be followed when bleeding each brake.
  • There are a few cars that require the brakes to be bled differently, but in general, the brakes that are most distant from the master cylinder need to be bled first. The factory manual or your dealer’s service department should be able to provide you with this information if you need it.
  • Put one end of a piece of clear tubing with a diameter of 14 inches over the bleeding screw on the first brake that you will be bleeding, and put the other end into a catch container like a discarded beer can or plastic soda bottle that can be used to catch the fluid.
  • In order to keep any trapped air from sneaking back into the caliper, you will need to make sure that the tubing is long enough so that you can hang the catch container above the height of the bleeder screw; this will prevent any air trapped in the tubing from sneaking back into the caliper.
  • Make sure your car’s engine stays off while you bleed your brakes. Engage the brake pedal with the assistance of an assistant. Then ask your assistant to hold the brake pedal halfway to the ground while pumping the brake pedal several times. When pushed too far, it can damage piston seals and cause leaks if it drives the secondary piston of the master cylinder across sediments and deposits.
  • Make sure the brake pedal does not go more than halfway to the floor by placing a small block of wood underneath it. When the pedal is down, have your assistant yell out “Pressure.” Open the valve with the brake bleeder wrench.
  • During the hydraulic brake process, old brake fluid and air are forced from the brake line into the jar. The assistant should yell “Down” as soon as the pedal touches the wooden block and as soon as it touches the floor.
  • Be sure to close the bleeder valve as soon as possible. You may have to repeat this process several times until they do not come out any more air bubbles with the fluid after they release the pedal.
  • Check the fluid level in the master cylinder reservoir on a regular basis. If necessary, you may add brake fluid to keep it topped up.
  • If the fluid stream flowing through the clear tubing is free of air bubbles, then repeat the steps described above at the wheel location at least five times until a clear stream of fluid is flowing through the clear tubing without air bubbles.
  • The brake bleeder sequence in most cars starts with the rear wheel of the driver’s car. It continues with the rear wheel of the passenger’s car, the rear wheel of the passenger’s car, and finally the front wheel of the driver’s car. The sequence of these steps should, however, be followed as described in your owner’s manual.
  • During the brake bleed process, make sure you check the fluid level in the cylinder reservoir as well. Once you have completed this procedure, make sure each bleeded valve is securely closed, and then add fresh brake fluid to the cylinder reservoir.
  • Afterward, you will need to reinstall your wheels and lower your car back down to the ground.
  • As soon as you complete bleeding of all four brakes has been completed, ask your assistant to press hard on the pedal of the brake and then suddenly release the pressure.
  • Keep an eye on the fluid level in the reservoir of the master cylinder as it moves. If it is still found that air bubbles are still trapped in the system after a substantial fluid eruption. To remove that air, you must repeat the bleeding procedure. When the fluid is slightly disturbed, however, the brake system has been properly bled.
  • Make sure that all of the bleeder screws are tightened all the way down. Once again, apply solid pressure to tighten them, but don’t use your full strength – you do not want to snap them off before you install the wheels on the car – be careful not to snap them off.
  • If you want to tighten them, you need to put good pressure on them, but do not overdo it for fear of snapping them off before you have installed the wheels. Then you are finally done with the entire process of bleeding the brakes on your car.

Is it ever a good idea to bleed brakes?

There are certain brake issues that are not caused by any trapped air bubbles in the brake system, but by other factors

Some of these factors are:

  • During braking, the brake pedal tends to stay in the neutral position for a long period of time and the brakes tend to lock up.
  • There is a firm feeling to the brake pedal, but the ABS system is not working. There is a possibility that there is a problem with the ABS module.
  • It is possible that the brake rotors or brake pads could be worn out if your brakes make noise.
  • In the event that the brakes tend to lock and the brake pedal does not return to its neutral position within a short period of time.

Final Thoughts

The process of bleeding your car brakes involves a few steps, and it is absolutely crucial that you do this brake repair correctly.

It is advisable to leave this brake service to the professionals even if you know how to do it yourself as it is a risky and tiresome process.

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