What is a Brake Flush? | Autance

Changing your car’s brake fluid on a regular basis helps maintain the integrity of the vehicle’s brake system. In addition,…

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What is a Brake Flush? | Autance © What is a Brake Flush? | Autance

Changing your car’s brake fluid on a regular basis helps maintain the integrity of the vehicle’s brake system. In addition, there are instances when flushing the brake system can give your car a fresh start. Brake flushing is a procedure that is often recommended when certain symptoms of brake issues start to arise. While topping off or changing your brake fluid may solve these issues, only a brake flush may give you the kind of results that you need.

Related Post: Best Brake Fluid

What a Brake Flush Is

Brake flush is the process of removing the brake fluid from the vehicle’s brake system and replacing it with a new and clean brake fluid. It is a lot similar to flushing other fluids in your vehicle such as the engine oil and transmission fluid.

There is another process that many vehicle owners mistake for brake flushing. This is brake bleeding. It is very easy to differentiate the two.

In brake flushing, the entire brake fluid content of the system gets removed and replaced with clean fluid.

Brake bleeding only removes a portion of the brake fluid. This is often done if the problem involves the presence of air bubbles in the vehicle brake system. Bleeding the brake fluid will only remove that part of the fluid that contains the air bubbles.

Related Post: Best Car Brakes

Why Brake Flush is Important

Modern brake systems are not indestructible. Every single component of the system is still at risk of deterioration. The rubber parts in the master cylinder’s valves can deteriorate. The wheel cylinders and brake calipers can also show signs of degradation over time. Some components can chip off and send tiny fragments into the brake fluid.

Dust and brake metal particles can also accumulate in joints. These can find their way into the brake fluid and contaminate it. The brake fluid itself is also vulnerable to degradation. You should keep in mind that brake fluids contain mineral oils as their base. These fluids come with additives that can change in chemical structure as they go through the system countless of times. As such the once-clean brake fluid in your system may now be dark and dirty.

There is also the possibility of moisture getting into the system. Moisture often enters via rubber brake lines where they interact with the molecules of the brake fluid. Excess moisture can also increase the temperature of the brake fluid. This is because water has a lower boiling point than brake fluid. This can introduce air bubbles into the brake fluid. The presence of air bubbles in brake fluid can lead to spongy brake pedals since air bubbles are compressible. All of these factors will contaminate the brake fluid.

The modern car employs a hydraulic brake system. Any change in the nature of the hydraulic fluid – the brake fluid – can result in a change in the brake system performance. For example, debris or particles in the brake fluid can weaken the brake master cylinder. The caliper rubber seals may also be affected. Overall, this can lead to a reduction in braking power.

If you are the type of driver who doesn’t go beyond 30 MPH, then this should not be an issue. But if you’re the type of driver who loves the rush of speeding on highways, then it becomes an issue. A minor problem in your brake system can have catastrophic consequences.

Car Symptoms that May Warrant a Brake Flush

Most car manufacturers recommend the changing of the brake fluid every 2 to 3 years or about 20,000 to 24,000 miles. There are also some vehicle manufacturers that do not have very specific recommendations as to when to change the brake fluid.

There are certain situations that may necessitate the performance of a brake flush on your vehicle. These are as follows.

  • Visible contamination in the brake fluid. The fluid may look dark brown or black.
  • The brake pedal feels odd, more like spongy.
  • Increased braking distance. For example, a car can come to a complete stop from 60 MPH after 150 feet. If there is a problem in the braking system, its braking distance can increase to 200 feet.

Any of these situations will warrant a brake flush regardless of the actual mileage of the car. Of course, there may be other causes to these symptoms. Your mechanic can help you zero-in on the exact cause. However, there’s a good chance that he will recommend brake flushing.

How to Perform a Brake Flush

Flushing your car’s brake system should be easy, but it can prove challenging to the novice vehicle owner. To brake flush your car, you need to perform the following.

  • Locate the master cylinder of your car’s brake system and open its cap. Draw out the brake fluid from the master cylinder using a turkey baster or a siphoning mechanism. Once done, the brake system may still contain about 20% brake fluid. Fill the master cylinder with new brake fluid.
  • Read your owner’s manual on how to proceed with the flushing process. In general, you need to bleed the brake caliper that is farthest from the brake reservoir first. For example, if the brake reservoir is in the engine bay, then you should start bleeding the brake calipers at the rear.
  • Jack up the side of the car that you have to bleed first. Remove the wheel so you can access the brake caliper. Also locate the bleeder valve.
  • Have someone pump the brakes 5 times until they notice the brake pedal getting stiffer. Ask them to hold the brake pedal down while you open the bleeder valve. This will force the fluid to come out.
  • Repeat the process several times until you see the brake fluid change from dark to lighter color. This is an indication that new brake fluid is already in the system.
  • Repeat the same process in the other brake calipers until you finish all four. Always check the brake fluid reservoir from time to time. Refill it with new brake fluid if it reaches the minimum level.
  • Upon completion, you can top off the reservoir with fresh brake fluid.

Flushing your car’s brake system can help improve overall brake performance. This can also improve the road-worthiness of your car.


  1. Brake System Flush at Your Home or Office – Your Mechanic
  2. How to Perform a Brake Fluid Flush – Do It Yourself
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