Brake fluid is a type of hydraulic fluid that is used in hydraulic brake and hydraulic clutch applications in automobiles, motorcycles, light trucks, and some bicycles. It is used to transfer force into pressure as well as to amplify the braking force. It works as the liquids are not appreciably compressible.
Most brake fluids used today are glycol-ether based, but mineral oil and silicone-based fluids are also easily available.
Brake fluid also called as hydraulic fluid, is responsible for moving the various components of your vehicle’s braking system. The fluid operates under high temperatures as well as high pressure and, without it, your car or truck would not be able to stop when you push the brake pedal inside your vehicle. Brake fluid is a non-compressible substance that lies within the brake lines and delivers the force created by your push on the brake pedal to each of the brake rotors on the four corners of your vehicle. This applies pressure to the wheels and slows or stops your movement. Here is a step-by-step and somewhat simplified look at how brake fluid works in a hydraulic brake system:
• The brake pedal is depressed by the driver.
• The pedal compresses a piston inside of the brake caliper.
• This compression increases the pressure inside the brake lines and then sends the brake fluid into motion.
• The pressure of the brake fluid then makes the brake rotors to squeeze down on brake pads, which then make contact with the wheels, slowing and eventually stopping wheel rotation as well as the vehicle itself.
Types of Brake Fluid
While brake fluid function is quite easy to understand, there is a wide variety to choose from, which might be confusing whenever it is time to replace the brake or hydraulic fluid. The two main types of brake fluid are glycol-based, which can be further divided by grade, and silicon-based fluids.
Glycol-Based Brake Fluids
They are typically used in vehicles with anti-lock brake systems (ABS). If a vehicle without anti-lock brakes has ever had glycol-based brake fluid, you cannot switch to a silicone-based one as small amounts of glycol will remain behind and chemically compromise the integrity of the silicone. Glycol-based fluids are classified by the Department of Transportation (DOT) number up to 5.1, which shows the boiling point of the fluid. Higher DOT numbers indicate better quality of hydraulic fluid that can easily withstand higher temperatures.
Silicone-based ones work only in cars and trucks without ABS technology.
Signs Indicating for a Brake Fluid Change.
Are you finding yourself pressing the brake pedal all the way or almost all the way to the floor of your car? There could be several reasons for this. The likeliest cause will be low brake fluid.
Are you pressing the brake pedal two or more times for bringing your car to a halt? The reason behind this will be low brake fluid.
Is your dashboard brake light on and is there the tell-tale sign of a brake fluid leak under your car? The spot will most probably be clear to brown and slick. Also, check your owner’s manual to place your brake fluid reservoir under the hood. The Low brake fluid in the reservoir (at or below the “MIN” or “minimum” line) can point out towards braking issues.
How to Change Brake Fluid
Car has to be jacked up for access to the bleeder screws. The bleeder screws generally look a lot like an old-fashioned grease fitting.
Once your vehicle is raised up and secured on jack stands, find, but don’t loosen, the brake bleeder screws on each wheel caliper or brake cylinder.
Find the master cylinder to remove the reservoir cap and old brake fluid with a vacuum pump. Then, Refill with new brake fluid.
• Attach the brake bleeder hose to the caliper bleeder screw as far as possible from the master cylinder (in other words, the right rear wheel) and put the other end of the tubing into a jar with about a 1/2″ of clean brake fluid in it. Loosen the bleeder screw and have someone press the brake pedal.
• Stubborn bleeder screws can be broken loose through trying to tighten them slightly first. Bleed until no air bubbles are visible while capturing the used brake fluid into the drain container. Tighten the bleeder screw and repeat this process as many times as necessary until no bubbles appear.
Add fresh brake fluid to the brake fluid reservoir and ensure the master cylinder reservoir never runs dry. Repeat step 4 while working closer to the master cylinder as you go. Refill the reservoir as required each time using only new brake fluid.
• After that, top off the brake fluid reservoir and replace the reservoir cap. Test the brake pedal before you drive the vehicle. You have finally finished a brake fluid change.
• Properly dispose of the used brake fluid at a facility near you.