Over time, brake fluid can start to retain moisture. This can eventually lead to corrosion and rust in the brake system. This can pose a significant problem, particularly in newer vehicles with ABS systems in place. It is also common for brake fluid to lose its viscosity because of the excessive heat generated by the braking system and car engine.
Flushing the brake system on a regular basis is highly recommended although an additional pair of hands will be required to depress the pedals during the bleeding process.
Step 1 - Remove Old Fluid and Add New Fluid
Park your car on a flat, level surface to prevent rolling when the vehicle is jacked into the air. Raise the hood of your vehicle and spray the master cylinder with a liberal coating of spray brake cleaning solution. Use a clean, lint-free cloth to wipe the master cylinder clean. This will help to prevent contamination of the brake system.
Open the cover of the master cylinder and remove as much of the old brake fluid as possible. You will find this easy to do using a large syringe although a turkey baster is a great alternative if a syringe isn’t available. Pour old brake fluid into the old container and dispose of carefully at a local garage or tip.
The empty reservoir can now be filled with new brake fluid.
Step 2 - Bleed the Valves
Jack the car up to gain access to the brakes. Placing the vehicle on axle stands might help in gaining easier access and is also safer than leaving it on a jack while working underneath. Release the bleeder valve carefully taking care not to break it. Penetrating oil will help if the bleeder valve is too tight to open. New vehicles using the diagonally split system should be loosened from corner to corner beginning with the right rear brake followed by the left front brake. This should be followed by the left rear brake and then the right front brake.
Place a small wooden block underneath the brake pedal to restrict movement and attach the plastic tubing to each bleeder valve individually. Open each valve as your assistant depresses the brake pedal to the block and tighten the valve each time the pedal is fully down. Continue doing this until the fluid is running clear through the tube. Repeat this process on each individual brake until all four valves have produced clear fluid. You may need to top up the reservoir several times during this particular stage.
Step 3 - Check the ABS Systems
ABS systems work differently and the brake should be depressed by your assistant while the engine is running. Once fully pressed down, the engine should be turned off and the valves should be opened for around 10 seconds before being tightened again. This process should continue until each valve is producing clear fluid through the plastic tubing. Once again, the reservoir may require topping up during this stage.
Once all four brakes are completed, remove the wooden block from underneath the brake pedal and ask your assistant to press and release the brake several times to release pressure in the brake system.