Moisture in your vehicle’s braking system can make your brake pedal feel vague and spongy, especially in cars with ABS. Let us look into how you can flush brake fluid in ABS-equipped vehicles.
Most drivers do not check on the status of their brakes until they stop working. Over time, it is common for parts of a car’s braking system, like the rubber in valves, calipers, wheel cylinders, and master cylinder deteriorate. Small bits flake off from such components, and they end up in the brake fluid. Similarly, the braking fluid may become old and worn out, or moisture may get in the fluid, leading to rust and corrosion in the braking system, which affects the efficiency and stopping power of your vehicle.
Primarily, brake fluid serves as the lifeblood to the braking system of a car. It is vital to regularly check on the status of your brakes as it ascertains your safety and the longevity of your car’s overall performance. Flushing brake fluid with ABS is possible with and without a scan tool by using the conventional vacuum or pressure method. Both methods are effective and can be done in the comfort of your own home.
What happens when air/moisture gets into the ABS?
Every time you open your braking system to repair or replace various components, air or moisture gets inside the braking system, and eventually, into the brake fluid due to its hygroscopic nature. Other ways brake fluid may gain air bubbles or humidity is when it becomes old and contaminated, or when exposed to heat, causing it to break down and shortening its lifespan.
Once air or moisture gets in the system, it compresses the air first, instead of facilitating the hydraulic fluid to transfer the pressure to other brake components, causing the brake pedals to become spongy and soft. As a result, there will be a decrease in overall stopping power, meaning it is time flush or bleed your brake fluid.
Many experts in the automobile industry recommend flushing brake fluid after every 48,280km (30,000miles) or so. Similarly, Volkswagen and BMW recommend a flush and fill every two years. It is also vital to note that there is a difference between brake flushing and brake bleeding. Brake flushing involves all the brake fluid from the braking system and replacing it with a new and clean alternative, while brake bleeding means removing just enough brake fluid to remove the air bubbles from the brake lines.
How to flush brake fluid in an ABS-equipped vehicle
The hydraulic control unit of your ABS-equipped vehicle requires fresh brake fluid now and then to prevent the corrosion of valves and passage lines, control the pH, viscosity, and cavitation in the braking system. As a general rule of thumb, most cars with anti-lock braking system flush their brake circuits in the same way, provided that no air is in the ABS modulator assembly. If the components you replaced were under the modulator, you could employ the brake fluid’s standard flushing procedures.
How to flush brake fluid without a scan tool
Flushing the ABS module of a car without a scan tool requires plenty of time and attention since you will have to repeat the procedure at each wheel one at a time. Luckily, the process is not complicated, especially if you enjoy working with your hands. Some items you may need for the flushing procedure include:
- New and fresh brake fluid
- Turkey baster
- Carjack, and jack stands
- Drip pan
- Lug wrench
Before you begin to flush your brake fluid, park your car on a flat and well-lighted area. Shift the gear to ‘parking’ mode and apply your emergency brakes to stop any unintended movement or rolling of the vehicle. Proceed to jack up the car and remove all of its four wheels so that you can easily access various parts of the braking system.
Raise your car to a reasonable height that allows you easily remove the wheels and effortlessly reach the desired areas. Use the jack stands to stabilize and hold the car in that position. You may need an extra set of hands to assist you as you go along with this process. Such a person should be able to follow instructions exactly as given.
Drain the existing brake fluid
Locate the brake fluid reservoir, which is a translucent tank with metal tubes in and out of every wheel, found under the hood of your car. Drain the existing fluid in the reservoir and refill it with fresh brake fluid.
Loosen the bleeder bolt by using the correct wrench and being careful not to remove it entirely from its socket. Detach the dust cap, and fix one end of the tubing to an empty plastic bottle while connecting the other end to the loose bleeder bolt.
Instruct your assistant to pump the brake pedal of the car until every last drop of the old brake fluid spurts out of the system and into the plastic bottle. Once no more fluid is coming out, check the reservoir to ensure it is entirely empty.
As you go about flushing the brake fluid, you should ensure the fluid level in the master cylinder does not drop below its midpoint. If its fluid drops below the half level, air will get into the system, meaning you will have to bleed it to remove the air bubbles as they may cause brake failure. Regularly check on the master cylinder and keep refilling it when its fluid is almost going below the midpoint.
When all the fluid has stopped spurting out from the bleeder bolt, tighten it and ask your assistant to continue pressing down the brake pedal until the bolt is tightened correctly. Repeat this flushing procedure at all the remaining wheels. You may begin with the left rear wheel, then the right front, then left front or start with the right rear one and proceed with the order, depending on your car model or ABS.
Reattach all the parts back together
Once you finish flushing the system, remember to put all the parts back together and ensure that no component in the braking system leaks. Ask your assistant to pump the pedal while you examine all the components you had put apart to see if there is any dripping. The helper should be careful to pump the pedal up and down to the recommended levels. Proceed to refill the master cylinder with fresh fluid until it reaches the ‘full’ point. Reaffix all the wheels and perform a test drive to ascertain that the brakes are working properly.
How to flush brake fluid with a scan tool
Flushing brake fluid is easier when you use a scan tool, such as an injector tool, vacuum bleeder, or power bleeder. The most common flushing procedure for vehicles with ABS is to begin flushing the brake fluid from the brake furthest from the master cylinder. Once completed, proceed to that which shares the same hydraulic circuit, and then to the brake furthest from the master cylinder.
Depending on the ABS configured, the flushing sequence may vary from one car model to the next, so it is best to consult a trusted mechanic and your vehicle’s manual for the best results. As a result, most people who flush the brake fluid in their ABS-equipped vehicle with a scan tool prefer taking it to the shop since the equipment used requires a specific type of prowess when operating it.
Not many ABS-enabled car owners understand the importance of flushing brake fluid, so they will likely need some education on how to meet the needs of their vehicle properly. It is crucial to change your brake fluid periodically to reduce the dangers associated with air-contaminated brake fluid. Not only does it extend the lifespan of your car’s braking system, but it also saves on costly repairs and replacements of the brake pressure modulator valve (bpmv).