How to Identify Air in Brake Fluid?
3 Answers
Methods to identify air in brake fluid: 1. Start the vehicle and press the brake pedal firmly. If the pedal sinks all the way to the floor, this indicates air in the system. 2. If the pedal feels normal after a few pumps but sinks again after releasing the pedal for a few minutes and then pressing it, this also suggests air in the brake system lines. Braking, also known as deceleration, refers to the action of stopping or reducing the speed of moving locomotives, vehicles, or other transportation tools or machinery. Brake fluid, generally referring to hydraulic brake fluid, is the liquid medium that transmits braking pressure in hydraulic braking systems and is used in vehicles equipped with hydraulic braking systems. There are three types of brake fluid: castor oil-based, synthetic, and mineral oil-based.
As a seasoned driver with years of experience, I mainly rely on the feel of the brake pedal to determine if there's air in the brake fluid. If air is present, the pedal will feel soft and overly elastic, lacking the usual firm and direct feedback. The pedal travel also becomes longer, requiring a deeper press to be effective. While driving, the braking performance noticeably deteriorates—especially in rainy conditions or at high speeds—resulting in insufficient braking force and an increased risk of rear-end collisions. I remember one time after maintenance when the system wasn’t properly bled; the brake pedal felt spongy while driving, and upon inspection, air was found in the system, prompting an immediate repair. Regularly checking for abnormal drops in brake fluid levels or bubbles can also hint at issues, but the most reliable method is periodic professional bleeding at a certified shop. Addressing these problems promptly helps prevent major accidents.
I enjoy DIY car repairs, and checking for air in the brake fluid is quite simple. After parking, press the brake pedal several times. If you feel a noticeable rebound or slow return, it's likely due to air. Then check the brake fluid reservoir—if the liquid level fluctuates unevenly or tiny bubbles emerge, that's another sign. Air usually seeps in from poorly sealed calipers or pipe connections, especially in high temperatures. Bleeding the brakes yourself requires tools; beginners can use a pump to evacuate the air, but don't force it for safety. Pay attention to changes in pedal resistance while driving—if it feels too soft, be cautious. Regularly replace the brake fluid and choose high-quality products to reduce air risks and ensure travel safety.
