Home CAR GUIDE BRAKING PARTS How Car Brake Fluid Works

How Car Brake Fluid Works

Brake fluid gets the force of your foot pressing on the brake pedal to the brakes to all four wheels. Fluid-filled, air-free channels extend from the master cylinder in the engine compartment through brake lines (rigid tubes) and flexible hoses to cylinders that make the calipers or drum brakes activated. In newer cars, antilock braking system hardware is used as an intermediate component.

Brake fluid reservoirs are usually made of translucent plastic to simplify checking the fluid level. Some cars show a warning light to indicate if the level drops too low. A healthy brake system won’t lose any fluid, though the level may decrease as the brake pads start to wear. Dramatic fluid loss is a cause leading to investigation. 

How to Add Brake Fluid to Your Car

Car brake fluid is necessary to keep your car brakes in proper working. Check brake fluid’s condition and top it off if it seems low or discoloured.

Here is you add brake fluid to your car:

How to add the Brake Fluid

  1. Park the vehicle on a levelled area – See if the vehicle is stationary and on a level surface. Making the vehicle to move or having it at a steep pitch can make the fluid levels read in an incorrect way.
  2. Depress the brake pedal by 20 to 30 times – Some manufacturers clearly specify that this be done if the vehicle has anti-lock brakes (ABS).

Tip: If your vehicle doesn’t have ABS, you can skip the mentioned step. If you’re not sure if you have ABS, do it anyway.

Warning: The brake pedal might get hard when you do this with the engine off, which is just a normal condition. The normal pedal feel will automatically return when the engine is started again.

  • Locate the location of brake fluid reservoir – The brake fluid reservoir is usually located under the hood, on the driver side of the vehicle, against the back of the engine compartment or might be near the base of the windshield.

Tip: Some vehicles usually have the brake fluid reservoir under a plastic access panel.

Tip: Some vehicles require significant disassembly of panels present underneath the hood in order to access the brake fluid reservoir. If the same is the case on your vehicle, the best option may be best to have a professional perform this service for you.

  • Examine the brake fluid’s level – Most modern vehicles take a plastic reservoir that is transparent and has MAX and MIN marks on it. If this type is yours, then you should be able to see if the brake fluid is between these marks.
  • Inspect the colour of the brake fluid – Brake fluid becomes contaminated when used normally. Clean fluid is in light golden yellow colour, dirty fluid changes to dark amber in colour. If yours is dark, you should contact a professional about having the brake fluid to be flushed. Some older vehicles have a metal reservoir with a metal cap that needs to be removed to watch the level. If yours is of this style, then proceed to the next step. If your brake fluid level between the marks and the fluid looks clean, then job are finished. Well Done!

Tip: Shining a flashlight into the reservoir will help you to see the fluid level and if the reservoir is dirty or not. Otherwise it’s difficult to see through.

  • Open the fluid reservoir by removing its cap – If your fluid level is below its minimum mark, or if you cannot see your brake fluid level with the cap on, you need to be careful while removing the cap.
  • Cleaning of the reservoir – Just take a clean rag and wipe all the dirt and grease away from the cap and the top of the reservoir. You may need to unplug the level sensor if there is one constructed into the cap.
  • Remove its cap – Remove its cap by pulling it straight up, by unscrewing it, or releasing the metal spring clip, whichever might be applicable.
  • Adding brake fluid to the reservoir – Slowly and steadily add brake fluid to the reservoir until it’s at the desired level. Be quite sure to use the correct brake fluid for your car. Reference your owner’s car manual or a professional to determine the correct fluid.

Warning: Do not fill above to the maximum line, the fluid needs an extra room in the reservoir to expand when conditions change.

Warning: Careful not to spill it. If you do, clean it up as soon as possible.

 10. Capping the reservoir – Re-install the fluid reservoir’s cap. Put the cap back the same way it came off.

Tip: Don’t forget to plug in the sensor if you to unplugged one earlier.

Congratulations! You’ve done the job! Your brake fluid is now at the correct level. If the fluid was low, there might have been a problem in the system, such as brake components worn out.

The Braking System

Let’s start with the basic explanation of a vehicle braking system, as understanding the system is critical to understand why the brake fluid is so important. A basic hydraulic brake system is made of a master cylinder, brake fluid and a fluid reservoir, and of brake lines, and brake calipers (disc brakes) or wheel cylinders (drum brakes) applying force to the brake pads or shoes at each of the four wheels.

A brake pedal is directly attached to the master cylinder, which is where the brake fluid is distributed to all the wheels through separate brake lines. The brake fluid reservoir is mounted above the master cylinder, useing gravity to feed fluid into the master cylinder. When the pedal is being pressed, the master cylinder puts pressure on the fluid. Since fluids can’t be compressed, this pressure starts to become a movement. The fluid moves in the brake lines and down into each brake caliper or wheel cylinder. There the fluid pressure applies force to the brake pads or shoes which makes the wheels to stop.

Why is it important?

This process applies to most vehicles, but depending on your model, there might be variations that could require additional work or service by a professional.

  • Brake fluid is hygroscopic, which means it absorbs moisture, including the moisture in the atmosphere. Don’t leave the reservoir or any fluid open any longer than necessary. Because it’s hygroscopic, the fluid should be flushed every 2 years regardless of any colour or condition of fluid. This ensures there is no moisture in the fluid that can corrode parts internally.
  • Brake fluid is damages the painted surfaces – even a drop can cause the damage. Immediately clean up all spills with a household cleaner or degreaser and a clean rag.
  • If the brake pedal is quite low or spongy, it’s a good idea to take the help of a qualified technician, as those could be a new sign of a more serious issue.

If you might had to add any fluid, you should inspect the brake system by a qualified professional.

Video of How to Add Brake fluid

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