Why is the brake fluid decreasing?
4 Answers
The reasons for the decreasing brake fluid are: 1. Severe wear of the brake pads; 2. Leakage in the brake fluid pipeline. Brake fluid, also known as hydraulic brake fluid, is a functional liquid that transmits pressure in the vehicle's braking system, enabling the braking action of the wheel's braking system. The functions of brake fluid are: 1. Brake fluid has a very low freezing point, ensuring good fluidity in low-temperature conditions; 2. Brake fluid has an extremely high boiling point, preventing vapor lock in high-temperature conditions; 3. It does not cause corrosion to metals and rubber. The reasons for replacing brake fluid are: 1. Moisture or impurities from the air can enter through the vent hole of the fluid reservoir, lowering the boiling point of the brake fluid; 2. During prolonged braking, the brake pipelines are prone to vapor lock, leading to reduced braking force or brake failure.
Speaking of brake fluid level dropping, I've seen plenty of cases in this line of work. The most common cause is system leakage - either aging or cracked master cylinder seals, or loose connections at wheel cylinders. Another reason could be worn brake pads - the automatic adjuster compensates, causing fluid level to drop. It might also be an improperly tightened reservoir cap, or corroded brake lines developing holes. I remember a friend's Toyota once had rusted-through lines leaking fluid. Safety-wise, remember that low brake fluid means reduced stopping power, and in extreme cases complete brake failure. My advice: if you notice low fluid, immediately inspect lines and reservoir for leaks, checking inside wheel wells for oil stains. During routine maintenance, ask technicians to perform pressure tests for leaks. Make it a habit to glance at the reservoir level before driving - this simple check could save lives.
My old classic car also had an issue with low brake fluid, which gave me quite a scare. The main cause was fluid leakage, as rubber seals in components like the master cylinder or wheel cylinders can degrade and crack over time. Another possibility is brake pad wear reaching the limit point, prompting the system to automatically add fluid to compensate for the gap. Driving habits also play a role—frequent hard braking accelerates system wear. Safety is non-negotiable; low fluid levels can lead to spongy brakes or even failure. That time, I noticed a longer pedal travel after returning from the city, and a repair shop diagnosed it as a leaking wheel cylinder. The mechanic said it was lucky I hadn’t hit the highway, or a dangerous situation would’ve been unavoidable. I recommend car owners check the reservoir at least monthly, top up with the correct fluid type, and maintain cleanliness to extend its lifespan.
Brake fluid reduction usually stems from leaks or component wear. The system may have cracks in the master cylinder, pipes, or wheel cylinders, allowing fluid to slowly seep out; it could also be due to brake pads thinning, triggering the automatic adjustment mechanism and consuming more fluid. During inspection, first check if the fluid reservoir is clean and free of stains, then look for any oil traces on the inner side of the wheels. Safety first—low fluid levels can cause delayed brake response, increasing the risk of rear-end collisions. Promptly send for leak inspection and repairs without delay.
