What Causes Brake Fluid Leakage?
3 Answers
Brake fluid leakage may be caused by aging of metal or rubber components in the braking system, or damage to the braking system due to impacts during driving. Methods to check for brake fluid leakage are as follows: 1. Let the engine idle and set the transmission to "neutral," then press the brake pedal and maintain constant foot pressure. If the pedal slowly sinks under constant pressure, it may indicate a leak in the hydraulic brake system. Perform a visual inspection to confirm any leakage. 2. Check the fluid level in the master cylinder reservoir. Normal wear of friction linings may cause a slight drop in the reservoir level. If the reservoir level drops abnormally, it may trigger the brake warning light, indicating potential internal or external leakage in the hydraulic system. 3. Inspect the connections of brake lines and hoses for leaks. If leaks are found, check the torque of fasteners or replace the lines or hoses. 4. Examine the components connected to the brakes for damage. If necessary, reinstall or replace these components. Also, check the protective covers of calipers and wheel cylinders for leaks. If leaks are confirmed, reinstall or replace these components as needed.
In my over ten years of driving experience, I've found several most common causes of brake fluid leaks: First, aging or damaged brake lines, especially in older cars where plastic tubes can become brittle over time or crack from stone impacts, causing fluid to seep out; second, loose connections, such as an improperly tightened cap when adding brake fluid or worn seals at certain joints in the braking system; third, poor piston sealing in the master cylinder or wheel cylinders, leading to continuous leakage; and fourth, deformed or punctured brake lines due to scraping against the vehicle's undercarriage. Once, my own car had a large gash on the undercarriage, causing all the brake fluid to leak out. If not discovered in time, brake failure on the highway could have had dire consequences. Regular maintenance should include checking brake fluid levels periodically. If the fluid level drops below the standard line, it may indicate a leak. Brake fluid stains are typically yellow and transparent—clues can be found by checking for oil stains near the inner side of the tires or under the engine bay. Get it fixed immediately, as this directly affects braking performance and safety should never be taken lightly.
Over the years of working with car modifications, I've learned that brake fluid leaks can stem from various factors. Aging oil line materials are most prone to wearing out under high temperatures or rough road conditions. If the sealing gasket in the brake system's hose connection is damaged or loose, fluid can leak from there. Another common issue is damage to the piston seal ring in the brake caliper, which prevents the system from maintaining pressure. Improper modifications are also a significant problem—for instance, failing to properly handle connections when swapping performance parts or using substandard components can lead to leaks. Additionally, cracks in the brake fluid reservoir or a loose reservoir cap can cause seepage. I recommend developing a routine: check the fluid level in the reservoir weekly, don’t wait for the warning light to come on. If you notice the brake pedal feeling soft or weak after a leak, pull over immediately to inspect. Never take it lightly—safe driving is paramount.
