Can’t Build Pressure When Bleeding Brakes

If your brakes are getting spongy, you might try bleeding your brakes. But what happens if you can’t build pressure when bleeding brakes, despite several tries? Read on to know what to do.

Air or moisture inside your brake fluid makes your brakes soft and, therefore, ineffective for braking. Bleeding brakes is the process of opening the small valve of the caliper or the wheel cylinder and allow the brake fluid to go out of the system. Bleeding removes air and moisture from your brake fluid, making your brakes healthy again.

One very common problem that our readers ask us is that they can’t build pressure when bleeding brakes. It’s frustrating when you bleed your brakes several times, but you still find your pedal spongy and sinking to the floor. This Indicates your brake pedal still does not have sufficient pressure to stop the vehicle, which can be very dangerous for the driver and those near them. 

There can be several reasons for pressure not building on your brake pedal. This article will list some of the reasons for not building pressure even after bleeding brakes. I hope it will help you in solving this problem.

 

Can't Build Pressure When Bleeding Brakes

Why Do You Need To Bleed Your Brakes?

The brakes lines of your vehicle contain brake fluid. This fluid is essential in transmitting force from the brake pedal to the brake pads and caliper, which finally helps in slowing down and stopping your vehicle.

But when the air enters into your braking system, then your brake fails to stop the vehicle. Now the question comes how does the air enter into the system? The air may enter while cleaning the master cylinder or while cleaning the piston inside the caliper.

Again, the brake is hygroscopic by nature. When you use your vehicle brakes often, then it may heat the brake fluid. The water inside the brake fluid will also boil and convert into steam. This steam or vapor gets trapped inside your brake fluid, causing this problem.

Why Can’t You Build Pressure When Bleeding Brakes?

#1. There May Still Be Trapped Air Inside Your System

Whenever you notice sponginess in the brakes, you may try to bleed the brakes. Many people try the manual syringe method to remove the excess air. When they do not notice any air bubbles from the valve, they think they have completed the bleeding process. 

But that is not always true. There may be some tiny air bubbles inside the brake lines, causing your brake pedal to sink to the floor. 

For instance, air traps inside the brake lines and buoyant air will not go down to the caliper. So, you get spongy brakes but are unable to remove the air from the brake lines.

Well, bleeding the brakes is not a tough job. But incorrect bleeding may cause serious problems. So I have listed some solutions for you.

 

Can't Build Pressure When Bleeding Brakes

 

Solution

  • You need first to bleed your master cylinder and then move to the brakes.
  • Tighten the bleeding screw and keep on pumping till all the air comes out.
  • You can take your vehicle to the technician or nearby garage, and he will repeat the bleeding procedure.
  • If you are trying to remove the trapped air manually, you need to repeat the bleeding procedure more than three times. Remember, patience is essential in this procedure.
  • Whenever you bleed the brakes manually, then try to bleed one caliper at a time. Remember to start from the caliper, which is far from the master cylinder.
  • All the fittings should be completely tight, and there should not be leakage of brake fluid anywhere from the system. But if you notice leaks, then disassemble the leaking connection. Inspect and stop the leakage and then once again reinstall it.
  • You bleed the air from each of your wheels till all the air comes out.
  • The reservoir should have fluid at all times while bleeding.
  • You can try other bleeding methods to remove the excess air, like the gravity bleeding method, which is one of the easiest ways to bleed brakes.

#2. Damaged Brake Lines

If the brake lines are damaged because of accidents or have already corroded, it will allow the air to enter the system. So even if you bleed brakes, you will experience spongy brakes, and your brake pedal will go down into the floor.

Solution

You need to inspect all the brake cables and then change your brake lines as soon as possible.

 

Can't Build Pressure When Bleeding Brakes

#3. Faulty Bleeding Screw

The bleeding screw is present on the exterior of the brake caliper or wheel cylinder. This screw helps in removing the trapped air from the brakes.

Unfortunately, the heat generated in the caliper, salts on the road, or moisture can corrode the bleeding screw, causing the screw to break. A damaged bleed screw allows air to enter the system.

So if you don’t notice the bleeding screw and do the bleeding process, you might end up with your brake pedal without pressure despite bleeding many times.

Solution

Try to change the bleeding screws quickly.

#4.Faulty Brake Caliper

Nowadays, you will find a free-floating brake caliper in your vehicle. These calipers don’t fit directly to the hub but slide on lubricated pins. When your car becomes older these pins will break down and allow moisture into the brake system.

 

The piston may also fasten with the caliper because of the moisture attracting capacity of the brake fluid. The moisture can even corrode the piston. The seals of the piston also need to be in good condition. Otherwise, it will attract unnecessary air into the system.

So, if you have a faulty brake caliper and still do the bleeding process, you will experience spongy brakes repeatedly.

Solution

Buy a new brake caliper

 

Can't Build Pressure When Bleeding Brakes

#5. Fitting Incorrect Brake Caliper

Sometimes you change your brake caliper for some reason. But if you fit the right-hand caliper on the left and vice versa, then it will surely invite unwanted air into the system, which may result in developing inadequate pressure on your brake pedal.

Solution

Always try to fit the caliper with bleeding screws towards the top to remove the trapped air from the caliper easily.

#6.Faulty Master Cylinder

The piston seals in the master cylinder may rust or dry over time, inviting unwanted air into the system. So if you carry out the bleeding process without seeing the faults in your master cylinder, you will experience a spongy pedal, or your pedal will not have sufficient force each time.

Solution

  • Change the piston seals of your master cylinder.
  • Try to remove the air properly from the master cylinder.

 

Can't Build Pressure When Bleeding Brakes

Frequently asked questions

#1. Why do brakes won’t pump when they bleed?

The brakes do not bleed for various reasons. Some of the reasons are

  • Incorrect bleed procedure
  • Fault in bleeding screw
  • Fault in calipers
  • Fault in the master cylinder

#2. Why won’t my brakes build up pressure?

Your brakes may not build up the pressure because of several reasons like

  • Air introduced into the braking system
  • Corrode piston seals in the master cylinder or wheel cylinder
  • Corrosion of brake lines

#3. Why is my master cylinder not building pressure?

If your master cylinder has internal brake fluid leakage or rust piston seals, it may not build pressure.

#4. Should the master cylinder be closed when bleeding brakes?

The cap of the master cylinder should be open during bleeding brakes to remove all the air from the system.

 

Can't Build Pressure When Bleeding Brakes

Wrap Up

Bleeding or flushing of brake fluid is quite essential to increase the efficiency of your vehicle. Sometimes things may not be under your control. You try to do the bleeding process many times, but still, your brake pedal does not build up pressure.

In this article, I have helped you understand the possible reasons for no pressure on the brake pedal even after bleeding many times. 

If you cannot diagnose such problems in your vehicle, it’s best to take your vehicle to the nearest garage. The mechanic will identify the problem easily and solve it as soon as possible after all faulty brakes are dangerous for your life.

 

Happy Driving!