How to Bleed Brake Fluid?
3 Answers
The method to bleed brake fluid is to continuously press the brake pedal 5 to 6 times, then hold the brake pedal down. Repeat this action until the brake fluid shoots out in a straight line from the air screw. Below is an introduction to brake fluid: 1. Introduction: Brake fluid, also known as brake oil or hydraulic brake fluid, is made from refined diesel distillate with thickeners and antioxidants. There are three types: mineral oil brake fluid, alcohol-based brake fluid, and synthetic brake fluid. 2. Note: When purchasing, choose a reliable manufacturer, and the higher the grade, the better. Its working pressure is generally 2MPa, and can reach up to 4~5MPa. 3. Property: All liquids have the characteristic of being incompressible. In a sealed container or a pipeline filled with liquid, when the liquid is under pressure, it quickly and uniformly transmits the pressure to all parts of the liquid. Hydraulic braking works on this principle.
Last time I changed the brake fluid myself, it took me a whole day. First, I prepared a transparent plastic hose to attach to the brake caliper bleeder valve, with the other end inserted into a bottle for collecting the waste fluid. I needed a helper to pump the brake pedal inside the car while I loosened the bleeder valve on my end, watching as the old fluid mixed with bubbles flowed out. Remember to keep topping up the reservoir with new fluid to prevent air from being sucked back in. Each wheel had to go through this process, with the right rear wheel being the most troublesome—I had to lie on the ground for half an hour to get it done. After finishing, I repeatedly pumped the brake pedal until I felt resistance. Honestly, this job requires two people to cooperate; it's really tough to do alone. In the end, I had to take the car for a slow test drive to make sure the brakes were working properly.
As a seasoned car enthusiast, my advice is to follow these five steps. You'll need to prepare the tools: new brake fluid, a clear hose, a wrench, and a container. Start with the wheel farthest from the brake master cylinder—right rear, left rear, right front, then left front. For each wheel, one person should press the brake pedal while another loosens the bleeder valve. Key points: maintain steady pressure when pressing the brake, ensure the hose is submerged in fluid to prevent air entry, and constantly monitor the fluid level in the reservoir. I recommend using DOT4 fluid for its higher boiling point and enhanced safety. After completing the process, remember to clean any areas where brake fluid may have come into contact with paint, as it is highly corrosive. The entire procedure should take about an hour.
