When you go to the petrol station to fill up your vehicle and check your oil and water, do you also check your brake fluid? For most people, the answer is no, but you should. Brake fluid is a vital component of your hydraulic brake system. It is necessary for the comfort and safety of you and your passengers.
But how do you know if you need brake fluid?
And what happens if you don’t change the brake fluid?
Well, we’ve got the answers below, including the best time to change it, signs your brake fluid is low, and the dangers of not changing it.
What is brake fluid?
Brake fluid is the liquid chemical solution used in hydraulic brakes and clutches in modern vehicles. It is designed to transfer force into pressure and amplify your foot’s strength on the brake pedal. Without it, stopping your car would take much more power than your foot.
The hydraulic fluid works because liquids are incompressible. However, it must be the correct viscosity and boiling point and be corrosive resistant:
- The proper viscosity: Brake fluid must be formulated perfectly to be effective. Firstly, it must have a constant consistency under a wide range of temperatures. You can check your vehicle’s correct brake fluid type in the owner’s manual or ask your local JAX expert.
- Resists corrosion: Brake fluid requires additives that manufacturers formulate to prevent corrosion in the brake lines. In winter conditions, the salt that lines the road can easily coat the undercarriage of cars and trucks, allowing moisture to create an acid that corrodes and rusts these metal parts. This corrosion is extremely dangerous.
- High boiling point: The braking system generates considerable heat due to the friction created by the brake pads. If the brake fluid did not have a high boiling point, the liquid could quickly vaporise into gas, and the brakes will lose effectiveness.
- Correct specifications: Manufacturers make brake fluids with different bases, usually glycol or silicon-based. You should never mix these two types, so you must know which brake fluid you use.
Why you should have your brake fluid checked
Brake fluid is a vital component needed to keep your brakes working. However, over time, like anything in your car, the brake fluid must be checked and changed.
On top of that, you should make sure to change your brake fluid following the recommendations on your owner’s manual or recommended by technicians based on copper level testing results. Avoiding checking your brake fluid can lead to avoidable damage that can require costly repairs.
You need to check your brake fluid for a couple of reasons - all of which are because the fluid loses effectiveness over time:
- Brake fluid is hygroscopic: Hygroscopic is a fancy way to say it readily absorbs moisture from the air. Now while the braking system is meant to be closed, it still takes in small amounts of moisture. Over time, the exposure can increase the water content inside the fluid, which decreases your brake fluids’ boiling point.
- Corrosion in the brake lines: Brake fluid has antioxidants and inhibitors to reduce the chance of corrosion in the brake lines. However, over time, these inhibitors break down, and corrosion can build, disrupting the flow of the brake fluid.
The short answer is no. Before you can add brake fluid, you need to flush the system.
Moisture-laden brake fluid can cause metal components to rust, resulting in rust particles in the liquid. On top of this, other dirt and grime that has found their way through the brake system. You must flush this out of the system before adding new brake fluid. Before adding brake fluid, you will need to:
- Find the brake master cylinder and clean it with brake cleaner spray. Make sure it cleans the reservoir and cap to prevent dirt or water from entering while you service it.
- Extract the old fluid using either the vacuum or pressure bleeding method. You will need to buy the appropriate equipment for this.
- You need to raise the car slightly to access each brake individually and press the brake down slightly.
- Repeat this process for each wheel
Changing your brake fluid yourself is not particularly difficult. However, it’s a somewhat messy and time-consuming job. You can do it yourself if you are willing to get your hands and probably clothes dirty. The necessary tools can also be expensive, even if the liquid is relatively cheap. However, your local mechanic will have all the tools and knowledge essential to do the job correctly.
While brake fluid can be another “out of sight, out of mind” car component, it works hard to keep you and your passengers safe and comfortable. There are a few ways you can noticeably tell if you need to change your brake fluid:
- Soft, bouncy or spongy brake pedal: If your brake pedal feels spongy or you can push the brake pedal down to the floor before it stops your vehicle, this is a sign you might need to change your brake fluid. Low fluid will cause air gaps in your brake line, leading to bouncy brakes.
- Poor braking performance: Modern vehicles have quick responsive brakes to keep you and your passengers safe in an emergency. If any delays or difficulties stop your car, this is a sign that your brakes and possibly fluid need servicing.
- ABS Dashboard light: Low brake fluid automatically turns in the ABS to help your vehicle continue to stop safely.
As with most car repairs, how often you need to change brake fluid will vary from vehicle make and model as well as the particular fluid used. Generally speaking, your brake fluid should last up to two years or 50,000 kilometres, whichever comes first.
It’s essential to have your brakes checked. Brake fluid is prone to bringing moisture into the braking system, reducing the fluids boiling point and leading to the eventual corrosion of expensive braking system components.
When you don’t change your brake fluid, your car’s braking effectiveness diminishes, resulting in poor braking performance. When you skip out on changing the brake fluid, the following things can happen:
- Corrosion in the brake lines: Brake fluid has antioxidants and inhibitors to reduce the chance of corrosion in the brake lines. However, over time, these inhibitors break down, and corrosion can build, disrupting the flow of the brake fluid.
- Moisture contamination: Brake fluid is hygroscopic - a fancy way to say it readily absorbs moisture from the air. Over time, the exposure can increase the water content inside the liquid, which decreases your brake fluids’ boiling point.
- Debris buildup: Various seals and hoses that make up your brake system shed tiny amounts of rubber as they age. As your brake fluid also ages, it can become contaminated with this debris. Moreover, moisture-laden brake fluid can cause metal components to rust, resulting in rust particles in the liquid.
- Braking performance: When you don’t change your brake fluid, your braking performance can suffer greatly. If left unattended, this can put you and your passengers in grave danger, especially if they fail altogether.
The short answer is no. You can’t drive without brake fluid.
Brake fluid is vital in powering your hydraulic system. It is designed to transfer force into pressure and amplify your foot’s strength on the brake pedal. Without it, the brake pad won’t respond when you move your pedal, as the entire brake system will have no “middleman” to connect the brake pedal to the brakes.
- Poor braking performance: Modern vehicles have quick responsive brakes to keep you and your passengers safe. If the brake fluid is too low, this is detrimentally affected.
- Spongy or bouncy brakes: Low fluid will cause air gaps in your brake line, leading to bouncy brakes.
- Corrosion in the brake lines: Brake fluid has antioxidants and inhibitors to reduce the chance of corrosion in the brake lines. Without it, your brake lines can start to rust.
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