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The Brake Fluid Is Black: What Does It Mean?
If you open the car’s brake fluid reservoir and you notice black or brown fluid. So what happened to your car? We’re sorry to say that black brake fluid is a sign that your fluid is highly contaminated. When this happens, the braking system’s ability to pressurize is reduced and brake performance may be affected. Besides, black brake fluid means that the rubber gasket has deteriorated and the liquid in the tank is too old and needs to be replaced. In fact, it turns out that brake fluid contaminants are attacking the rubber seals and washers. The black color in the liquid is the carbon particles from the rubber pads.
Why does brake fluid turn black?
Many drivers said that black brake fluid is caused by its age. It’s a true opinion. Like other fluids, the brake fluid will degrade after a long period and it needs to be replaced. After a while, your brake fluid will accumulate enough contaminants and cause the color to begin to change. This changeover will change from clear/yellow to a darker yellow, and when brake fluid is brown or black, this can seriously affect the braking system.
Inside the brake system is the brake fluid tank. From this reservoir, brake fluid travels its way from the cylinder to the car’s wheels. If you frequently step on the brake, the brake fluid will get contaminated faster. And even if you don’t drive as hard, as its feature, your brake fluid will still build up contaminants over time.
The second cause of discoloration in brake fluid is the deterioration of some parts in the brake system such as rubber brake lines, the gasket on the auxiliary cylinder, or the wheel. Because brake fluid is corrosive. Even though brake system components are designed to resist such corrosion. If not serviced or cared for properly, these parts will show signs of wear and tear. At this time, the microscopic pieces and soot of the rubber will follow the path to penetrate into the brake fluid. Discoloration as well as reducing the effectiveness of the fluid.
https://carfromjapan.com/article/car-maintenance/brake-fluid-is-black/