How to bleed car brakes

How To Bleed Your Car Brakes

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The brake fluid is an important component of the braking system as it transfers hydraulic forces from the master cylinder off to the corners of your car.

The brake fluid performs its functions efficiently because it remains in a liquid start throughout while also resisting compression.

Over time, however, the performance of the brake fluid drops, especially if it has air bubbles. If the sealing of the braking system is compromised, the air gets in the brake lines.

With air in the brake lines, the brake fluid boils and creates fluid vapor. With vapor/ air in the brake system, the system loses its efficiency. The primary cause of the inefficiency is the compressibility of air.

When there’s a large amount of air in the brake lines, pressing down on the brake pedal only causes air compression which causes the buildup of pressure in the corners of the brakes.

The air gives the brake pedals a soft or a spongy feel. In extreme cases, the brakes will fail to engage, putting your life at risk. Fortunately, you can avert the danger by bleeding the brake fluid.

Do I Need to Bleed My Brakes After Adding Fluid?

The bleeding of brakes refers to the process through you, or your car technician opens up a small valve at the wheel cylinder or the caliper, allowing the escape of controlled amounts of the brake fluid. So, despite its graphic annotations, bleeding of the brakes is simply the controlled release of your engine’s lifeblood.

So, should you bleed the brakes after adding brake fluid?

While it’s a known fact that air in the brake lines is a dangerous thing, you don’t have to add the brake fluid after you bleed the brakes necessarily. This is especially important if you are only adding the brake fluid because of the low levels of brake fluids, resulting from worn out brake pads, or if you’re only topping up the brake fluid to correct the level of the brake fluid.

The bleeding of the brakes is also unnecessary when you do a complete flush. For a complete flush, you need pressure bleeding. Pressure bleeding involves the removal of the cap on the brake fluid’s reservoir, connecting the pressurized source of the fresh fluid, and opening the blade screws systematically up until the brake fluid is clear. This flush auto-bleeds the system. The flush doesn’t introduce air into the brake lines.

When is it ideal to bleed the brakes after the addition of the brake fluid?

  • Empty Reservoir: If at the time of adding the braking fluid, the fluid reservoir is empty, bleeding is completely necessary. An empty reservoir means that the braking lines have been exposed to air.
  • Pumping of brakes: Besides the empty reservoir which means air into the brake system, you also can tell if bleeding is necessary or not by testing the brakes. You might want to bleed the brakes if pressing the brake pedal pumps up the brakes.
  • The pumping action means that the successive presses go down a slightly short distance because of air within the brake lines. Is this is the case, bleeding is essential.
  • Empty master cylinder: Bleeding after adding the brake fluid is also important if you note that the brake’s master cylinder is fully or partially empty. The emptiness of the master cylinder could result from leakage in the cylinder, leaking in the brake lines, or leaking in the seals or the brake pistons.
  • Replacement of brake fluid: if you’re replacing the brake fluid completely, bleeding of the brakes is crucial.

Can you just add brake fluid to your car?

Yes. If you note that the brake fluid is low as you replace the brake fluid, go ahead and replace the brake fluid. Just make sure you use the right brake fluid.

Here are the steps you should follow when adding brake fluid.

  • Park your car on a level surface then set the parking brake
  • If your car has ABS/ anti-lock brakes, you should depress your brake pedals 20-30 times.
  • Protect your hands and eyes from the toxic brake fluid
  • Keep your arms off the cooling fan because it can turn on automatically, even with the engine off. Roll up your clothes, if loose
  • Check the owner’s manual to ensure that you use the right brake fluid. This should be fluid from a clean and an unopened container. Do not substitute one brake fluid for another.
  • Also, you should never allow your vehicle’s master cylinder to run dry because this could result in the brake failure.
  • Now, with the engine off, raise the hood and then find the brake master cylinder (at the engine bay’s back side). Then cover up the fender before you open the master cylinder. Open the brake fluid container carefully to avoid damage to the car’s paint.
  • Clean the reservoir (master cylinder’s) using a clean cloth/ towel, and you should also clean up the fluid lines.
  • Check the fluid levels. Replace if the fluid level is below the MIN line.
  • If below the MIN level, pry off reservoir cap carefully then add the new brake fluid to the MAX line. Be careful not to overfill the reservoir. And don’t spill.
  • Clean the reservoir cap’s inside using a clean cloth or towel before putting it back.
  • Set the cap on the reservoir carefully and press down at it on all the corners till it clicks in place. If you unplugged the sensor, plug it back in.
  • Don’t forget to have your brakes inspected by a technician soon.

Do you put brake fluid in while the car is running?

No. it’s recommended only to add the brake fluid to your car when the engine is off.

How Long Does It Take to Bleed Brakes?

Brake bleeding is easily done by anyone with an intermediate skill level, as long as you understand the inner workings of the brake system, and you have the right tools. If this is the case, bleeding the brake fluid takes between 1 and 3 hours.

It’s important to recognize and get a handle of the brake problems early on. Fortunately, there are things that will guide your decision – the signs and symptoms you should watch for. They include:

  • Softening of the brake pedals
  • The need to press on the brake pedals all the way down for your vehicle to stop or slow down
  • Screeching, squeaking, or squishing sounds when you engage the brakes
  • After the replacement of the brake pads or the car’s brakes
  • Frequent hard braking
  • If you haven’t used your car months
  • It’s a necessity every two years or 24,000 miles

Remember that brake bleeding involves getting rid of the brake fluid with air bubbles.

The need for bleeding the brake system is also necessitated by the fact that the brake fluid is a chemical compound that isn’t inert and it will go through different chemical processes while in the brake lines. In contact with the metallic and the rubber parts of the brake system, and along with chemical processes, exposure to heat, oxidation, and moisture, the brake system undergoes degradation. These processes are beyond your control with the worst bit being the fact that they damage the brake seals and the brake lines, allowing air to leak into your brake system slowly. Bleeding prevents further damage to the brake lines.

How to Flush Brake Fluid with ABS

Is it time to flush out your ABS system’s brake fluid? How often should flushing be done? Your vehicle’s owner manual notes that brake flushing needs to bed one every 2-3 years to avoid and get rid of air buildup in the braking system.

With inherent risks like damage and reduction in the effectiveness of the brake system, how do you flush the ABS brake fluid.

Two or three years after changing the brake fluid, you should have a mechanic change things out, but you could also do this by yourself. The reason for the change in brake fluid is that with time, the brake fluid retains moisture which, in the long run, results in rusting and the corrosion of the brake system.

Corrosion and the rusting of the metallic parts of the brake system possess a significant risk, particularly to the new vehicles using ABS systems.

Other than moisture, you also need to be careful about the loss of viscosity in the brake fluid due to the generation of excess heat by the car’s engine and the braking system.

The only way of protecting the brake system from corrosion or loss of viscosity involves the flushing of the brake system’s fluid.

What is brake flushing?

A brake flush refers to the process that results in the removal of brake fluid from the brake system and replacing the old brake fluid with new and clean brake fluid. It’s a lot like the flushing of the transmission fluid or the engine oil.

Note that brake flushing is different from brake bleeding. With brake flushing, all the brake fluid in the brake system is eliminated and then replaced with clean and new brake fluid.

On the other hand, brake bleeding involves the removal of only a certain volume of brake fluid to get rid of brake fluid with air bubbles.

Importance of brake flushing

Your vehicle is not indestructible, and every component of your vehicle’s brake system is at risk of breaking down/ deteriorating. The system’s rubber parts located in the valves of the master cylinder could deteriorate, the brake calipers and the wheel cylinders could deteriorate, and other components will chip off, and the fragments get into the brake fluid.

The braking system’s metal particles and dust particles could also accumulate in the joints and eventually find their way to the brake fluid, causing contamination.

What’s more the brake fluid itself is prone to degradation. For example, the brake fluid has mineral oil as its base, and it also features additives which undergo chemical changes over time and due to the effects of things like temperature changes or exposure to water.

These chemicals and resultant reactions will leave you with a dark and dirty brake fluid that calls for immediate replacement.

Also, moisture which enters the brake system through the rubberized brake lines, and interacts with the brake fluid’s molecules. The moisture buildup, when in excess, will increase the brake fluid’ temperature, introducing air bubbles in the brake fluid. The air bubbles make the brake pedals smooth.

Finally, any changes in the nature of your car’s hydraulic braking system will change the performance of the brake system.

Therefore, brake fluid flushing is extremely important.

Which is the best way to change the brake fluid in an ABS?

  • First, check the vehicle’s DOT specifications and then find high-quality brake fluid from a reliable/ well-known manufacturer.
  • Don’t expose the new brake fluid to moisture because air will quickly contaminate the brake fluid – oxygen oxidizes the brake fluid lowering its boiling point significantly.
  • Locate your vehicle’s master cylinder then open up the cap. Once you’ve opened it, draw the brake fluid out of the master cylinder. Find a siphoning mechanism or a turkey baster for this when. Note that even when done, your braking system will still have about 20% of brake fluid. Now, fill the brake system’s master cylinder with the new and clean brake fluid and cap it off.
  • While at it, read the vehicle’s owner manual for details on the flushing process. Generally, though, you must bleed the brake’s caliper furthest (at the rear) from the reservoir first. For bleeding to run efficiently, jack up the vehicle’s side, you need to bleed first. You have to remove the wheel for access to the brake caliper and to locate your bleeder valve.
  • You need a helping hand when changing the brake fluid. With the car jacked up on one side, have the other person pump up the brake pedal at least five times or until the brake pedal stiffens. Then ask them to hold down the brake pedal as you open up the bleeder valve. Doing this will force out the excess brake fluid. Repeat this step until the brake fluid coming out is no longer dark, but light colored. The light brake fluid indicates that your new brake fluid is in the brake system.
  • You’ll have to repeat the step with the other three brake calipers. But, don’t do this blindly. Always check the level of the brake fluid in the reservoir from time to time, refilling when it reaches its minimum level.
  • When you finish bleeding the brake caliper, top up the brake system’s master cylinder with new brake fluid then cap it off.

Can brake fluid affect ABS?

Yes. Aged brake fluid or brake fluid leakage affects the efficiency of the hydraulics and this, in turn, affects the ability of the ABS to function well. ABS helps you stop your vehicle safety whenever you engage the brakes, but this system works well only if the braking system, including the brake fluid, is in good health. Aged brake fluid, for example, will affect the function of the hydraulic system and ABS by extension by increasing the system’s risk of damage from heat, corrosion, or friction.

How do you bleed air from ABS module?

As long as there’s no air in the ABS modulator assembly, you can bleed the ABS brakes manually using a vacuum bleeder or an injector tool, starting from the brakes furthest from your master cylinder first, followed by the brakes that share one hydraulic circuit.

But, if there are air bubbles in the ABS Modulators, ABS bleeding is necessary and you’ll have to use the special bleed screws which get rid of the trapped air. Bleeding will also depend on the type of ABS modulator affected.

How to Get Air Out of Brake Lines without Bleeding

The air in your car’s brake system gives your brake pedal a dangerous, spongy feel and you should let the air out often or as recommended by the brake fluid manufacture – that is; every 2-3 years.

If your car’s brakes start to feel squishy or if you have to press that car brake pedals all the way down and close to the car’s floor, look at your brake fluid and have the air in the brake lines removed as soon as possible.

The squishy feel of the brakes comes from the slow buildup of air in the brake fluid. Large amounts of air in the braking system causes possible braking failure, and if this situation is not addressed fast, you will find yourself in grave danger.

How can you tell if you have air in your brake lines?

Well, if you feel the softening of your car’s brakes, it’s highly likely that you have air in your brake lines.

Here’s the deal: your power brakes rely on the brake fluid which is why the brake fluid is regarded as the lifeblood of your vehicle’s braking system. Every time you press down on the brake pedal, there’s a transfer of hydraulic forces on to the brake calipers. The brake calipers will, in turn, press on to the brake pads and then the brake rotors, slowing down or stopping the vehicle.

Since air is less dense compared to brake fluid, the air in the brake fluid compressed easily, hence the spongy/ soft feel.

Still wondering what air in brake lines feel like? It feels soft and spongy on the brakes and the brake pedal that gets depressed farther and farther with time. Get the brakes checked out as soon as possible if you feel any of these symptoms.

How Does Air Get Into The Brake Lines?

Every time you press your brake pedal, you’re pushing the brake fluid with your leg’s action moving the plunger located in the brake master cylinder through the brake lines to the brakes. The plunger pumps the brake fluid.

As the fluid puts pressure on the brake pads and squeezes the brake discs, your car slows down/ stops.

Though the brake fluid has an airtight design and it’s expected to last a good number of years before the need for replacement, use and misuse of the vehicle affects the braking system. With time, the brake fluid loses its efficiency, and it allows air into the brake fluid. The main reason for this is that the brake pads wear down and you have to press the pedal further down, every time. While doing this, the brake clippers have to extend further in a bid to maintain a uniformity of distance. The piston is also forced to extend, and this creates a void in the braking system’s hydraulics.

All this time, your brake pads wear out, the demand for brake fluid increases, and more air is drawn into the braking system; hence the soft brake pedals.

Besides wear, poor servicing, leakage in the brake line, as well as poor driving and the constant slamming of the brakes will force air into the brake lines.

How to Get Rid of Air from the Brake Lines, Without Bleeding

The process of removing air from your brake lines is referred to as bleeding since it involves getting rid of the brake fluid (bleeding) and replacing the old brake fluid with new brake fluid.

While you’d be tempted to get rid of the air in the brake lines, without having to remove the old brake fluid, doing this means that you’re only postponing the problem. So, if you notice that your brake feels soft and spongy, you should consider seeking professional help.

If you choose to remove the air in the brake line at home, here are the steps you need to follow:

Find the brake bleeder Screw

The brake bleeder screw refers to the little nozzle behind the brakes. This nozzle’s more accessible when you jack up your car. If you choose to crawl beneath your car, lay down thick newspapers or an old blanket first. You could also find a creeper to lie on.

Loosen the screw

Once you find a comfortable position, get a good wrench fitting the screw properly then loosen the screw. A bleeder wrench works best, and it also prevents the rounding of the screw’s hex-head. Don’t break off the screw. After loosening the screw, tighten it slightly.

Put a hose over the bleeder

Place a small, flexible hose over the bleeder screw’s head, then out the other end of your hose in the jar and fill up the jar with the right brake fluid. Make sure that brake fluid covers the end of your hose. If you don’t have a hose, keep your jar close to the nozzle to allow the fluid squirting out to flow into the jar.

Pump the pedal

Meanwhile, ask your friend to pump the brake pedal slowly, up and down, while releasing it. Just make sure your car is not parked on a hill.

Open the bleeder screw

After pumping the pedal a few times, you should open the bleeder screw. Since the brake fluid will squirt out, be ready to duck. If there are any air bubbles in the brake fluid, you will see the bubbles in the jar or even the hose.

Tighten the bleeder screw

Before the release of the brake pedal, you should tighten the bleeder screw. Failure to do this will have the air sucked back into your brake lines upon the release of the brake pedal.

Release the pedal

After tightening the screw, ask your friend to release the pedal. Loosen and tighten the screw until the brake fluid is free of air bubbles.

Once in the clear, open up the master cylinder then add new brake fluid until the fluid reaches the designated Full line. This is an important step because you don’t want the master cylinder to dry out – it will draw in air from the top forcing you to work on the brake lines again to get rid of the air.

What to Do When there’s No Brake Fluid to Rear Brakes When Bleeding?

The brake fluid is responsible for the functioning of the brake system – the slowing down and stopping of the vehicle. Over time, however, the air gets trapped in the brake fluid, and the brake system loses its efficiency. Your brake pedals might feel soft and squishy, or you might hear squeaking or screeching noises every time you hit the brakes. If any of these happen, you know that there’s air build up in the braking system and you have to remove those bubbles. Bleeding is the best way of getting rid of the air bubbles.

Despite being the top-recommended remedy, bleeding fails sometimes. You might have followed the vehicle owner’s manual on bleeding and the right type of brake fluid to use, but what do you do when there’s no brake fluid to the rear brakes during bleeding? What even causes this scenario?

No Brake Fluid to Rear Brakes When Bleeding – Causes

Well, there are many possibilities for the rear brakes having no brake fluid during bleeding, but the most common reason for the absence of brake fluid from the rear brakes could be the result of the inflow of the brake fluid onto the proportional valve.

Often when this happens, and when there’s fluid supply to the valves, there’s a need for valve replacement.

If yours is an ABS with an electrical fault, light illumination on the dashboard will tell you that there’s a problem and you can read out the codes. However, if there’s no illumination, it means that there’s no electrical failure.

Note that the absence of brake fluid from the rear brakes could also result from improper bleeding of the vehicle and you can reverse this by using a freshly-bled master. This is an important step because you need to make sure that the master cylinder didn’t suck in air as you run your diagnostics.

Next, have someone pump up your master at the pedal and then loosen the master cylinder’s cap. Pump that pedal and them hold before loosening the master to let out the air.

Keep the pressure on the pedal until you’ve tightened the master fitting and until you find fluid.

You could also bench-bleed the master. For this, you should attach the brake lines then open the bleeders at all the corners of your car. Keep in mind that having a combination valve with a rubber boot to one end will simplify this. Under the boot, have a stem to be pushed down during bleeding.

Use a C-clamp to push in the stem. The combination valve holds off the pressure from the front brakes until a certain amount of pressure builds up within the rear brake lines.

However, if neither of the two possibilities above helps you identify the problem, you might have to enlist the services of an experienced mechanic.

What is The Correct Order to Bleed Brakes?

If you’re going to bleed your brakes at home without any help from a professional, you better make sure that you do the job right. And even though there are many people who cannot handle this technical process on their own, we know of many others wishing to make the brake bleeding process one of their DIY projects, hence this article.

The good news is that bleeding your brakes is quite easy, especially when you follow the correct steps.

The reason for this is that there is a right and wrong order of bleeding brakes. Here’s the correct order for bleeding the brakes.

Check the owner’s manual

First, you need to go through your vehicle’s user manual to check the specific type of brake fluid that your vehicle needs. The manual will also guide you on the frequency of replacing the brake fluid.

It’s important to consult the user manual because there are too many types of brake fluids on the market, and they hardly mix well or enhance the performance of your vehicle’s braking system.

Therefore, you need to make sure that the brake fluid you purchase is exactly what the vehicle manufacturer recommended.

Once you confirm the brake fluid needed by your car’s system, check its availability in your local auto store or dealer shop.

Getting the vehicle ready

Jack up your vehicle on a level and solid ground like the driveway or the garage floor, and support it using four jack stands at the jack points. Your user manual should have these details.

Stability is important for your safety, your property’s and your neighbor’s property, and it also ensures that you don’t break a limb as you climb under the car when bleeding the brake lines.

Locating the caliper bleeding screws

You need first to locate the caliper bleeding screws and then loosen them as gently as possible. Avoid twisting the screws with all your force. So, if they don’t loosen easily, find penetrating oil and loosen the screws with it. You’ll need to leave the screws soaking in the penetrating oil for about half an hour before you loosen the screws.

Remember that if the screws strip or snap off accidentally, you should stop what you’re doing and then take your vehicle to a dealer for them to deal with the problem professionally.

If you don’t face any difficulties and you’re able to loosen the screws easily, you should snug the screws up again.

The reason for this is that you don’t bleed all the brake lines at the same time, you have to bleed one brake at a time. Leaving all the screws open when you bleed introduces more air bubbles into the brake system, worsening the state of the brake system and reducing its performance.

Checking the fluid level

To check the level of your vehicle’s brake fluid, you need to pop the hood then check the fluid level in the brake master cylinder’s reservoir. The location of the master cylinder will also be shown in the owner’s manual.

If the brake fluid level is below the Full or MAX line of the reservoir, you should add fresh fluid.

Now that you have enough brake fluid, it’s time to bleed the brakes. Note that the master cylinder’s cap should be unscrewed but resting on the top of the reservoir.

The correct order of bleeding brakes?

In most cases, you need to ensure that you first bleed the brake located furthest from the master cylinder. In other cases, however, the order differs, and you must refer to the owner manual or seek guidance from the service department of the dealer.


Once you’ve determined the right bleeding brake to start with, fit the end of the bleeder screw (unscrewed) with clear tubing and then place the other end of the tubing in a clear container such as a clear beer or even a plastic soda bottle.

The tubing should be long enough o allow you to hang the container above the bleeder screw’s height. Doing this keeps out any air that could be trapped in the tube from getting back to the brake caliper.

To confirm bleeding is done correctly, involve your assistant (friend, child, or partner) and ask then to pump the brake pedal a few times or until they can feel a solid resistance under their foot. Do this with the engine turned off.

Even when your brake pedal feels firm, your assistant should maintain pressure on the brake pedal as you open a small space on the bleeder to allow the fluid to pass through.

When bleeding brakes What wheel do you start at?

If you have a dual-circuit system with a front disc-brake caliper with two pistons and brake cylinders in every caliper, bleeding should be done from the rear brakes then the two front calipers on the same side of your car.


When it comes to the overhaul of the brake fluid or the addition of brake fluid, you need to make sure that you protect yourself from the toxic fluid and keep all the parts ultra clean. Bleeding your brakes is something you should learn how to do because you are going to be needing it every 3 years of car travel.


Can one person bleed a car?

Yes, it is very possible for one person to bleed brakes as there several products in the market for this. You can also use vacuum pumps to make the easier. Bleeding brakes it also inexpensive and thus there several auto shop that offer the service at affordable prices.

Do I need to bleed all four wheels?

The rule is as long as you do not let the reserve dry there is no point in bleeding all your wheels at the same time. You can choose to just bleed the front wheels and later do the rear ones.

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