What is brake fluid and what does it do?
Written by Daily Fix - Published 08-Jul-2023, last updated 19-Mar-2024
Brake fluid is a type of hydraulic fluid used in hydraulic brake systems in cars, motorcycles, vans, light trucks, and even some bicycles. It is used to transfer force into pressure, and to amplify braking force. It works because liquids are not appreciably compressible. Most brake fluids used today are glycol-ether based, but mineral oil and silicone-based fluids are also available.
What does brake fluid do?
Brake fluid plays a crucial role in the operation of a vehicle's braking system. When the brake pedal is pressed, it exerts pressure on the brake fluid contained within the master cylinder. This pressure is then transmitted through a network of brake lines to the brake calipers located near each wheel.
Once it reaches the calipers, the hydraulic force provided by the brake fluid allows for effective braking by enabling them to squeeze the brake pads against the rotors. As a result, friction between these components leads to the deceleration or stopping of the wheels.
Brake fluid acts as an incompressible substance, ensuring that pressures exerted from pressing the brake pedal are evenly distributed throughout the braking system. It also operates at high temperatures without boiling or vaporizing, making it consistent and reliable in its performance.
How often should brake fluid be changed?
Check with the manufacturer guidelines for your particular vehicle, but in general brake fluid should be changed every 2 years or 30,000 miles, whichever comes first.
This is because brake fluid absorbs moisture over time, which can lower its boiling point and make the brakes less effective. If the brake fluid is too old or contaminated, it can also cause the brakes to feel spongy or unresponsive.Why does brake fluid need to be changed?
Brake fluid requires regular replacement due to its tendency to absorb moisture. Moisture can seep into the system through microscopic openings in the brake lines or even from the surrounding air. As time goes by, these water molecules accumulate in the fluid, causing it to become contaminated.
The accumulation of moisture in brake fluid can have several negative consequences. Firstly, it lowers the boiling point of the fluid. This can be problematic because during intense braking or emergency situations, the heat generated by friction can cause the brake fluid to boil. When this occurs, tiny air bubbles form within the system, leading to a phenomenon known as vapor lock. Vapor lock obstructs proper hydraulic pressure distribution and significantly reduces braking effectiveness.
Secondly, excessive moisture content in brake fluid can cause corrosion within the hydraulic components of the braking system: master cylinder, calipers, wheel cylinders, and ABS unit. Corrosion compromises their performance and longevity leading to potential failures.
Another issue arising from old or contaminated brake fluid is that it becomes more susceptible to oxidation and degradation over time. Oxidation can result in changes to the viscosity of the fluid, making it less efficient at transmitting force from the pedal to the calipers or wheel cylinders. Ultimately, this may cause a spongy brake pedal feel or unresponsiveness when attempting to engage the brakes.
Regularly replacing brake fluid not only helps maintain proper braking function but also prolongs the lifespan of critical components within your vehicle's braking system while ensuring reliable stopping power in emergencies. Consequently, neglecting this routine maintenance task could lead to compromised safety on the road and costly repairs in due course.
How do you change brake fluid?
Probaby, by taking your vehicle to a garage! But if you know your way around vehicle maintenance then you may wish to replace the brake fluid yourself.
The process typically involves flushing out all existing brake fluid from each component of the system and replenishing it with fresh fluid that meets or surpasses your vehicle's required specifications.
Again, check the instructions for your particular vehicle. Here are the general steps on how to change brake fluid:
- Park the car on a level surface
- Open the bonnet and locate the master cylinder
- Disconnect the brake lines from the master cylinder
- Dispose of the old brake fluid properly
- Fill the master cylinder with new brake fluid
- Connect the brake lines to the master cylinder
- Bleed the brakes
Here are some additional tips for changing brake fluid:
- Wear gloves and eye protection when working with brake fluid
- Make sure to use the correct type of brake fluid for your car
- Be careful not to overfill the master cylinder
- Bleed the brakes thoroughly to remove any air bubbles
Conclusion
Firstly, we recommend seeking professional help and advise if you think you may have problems with you car's braking system, or you think the brake fliud needs changing.
Brake fluid is an important part of your car's braking system, and it should be changed regularly to ensure that your brakes work properly.
Regularly replacing brake fluid not only helps maintain proper braking function but also prolongs the lifespan of critical components within your vehicle's braking system while ensuring reliable stopping power in emergencies. Consequently, neglecting this routine maintenance task could lead to compromised safety on the road and costly repairs in due course.