What to Do If the Brakes Feel Soft After Changing Brake Fluid?
3 Answers
If the brake fluid's performance is poor, it can lead to insufficient friction between the brake pads and brake discs. Over time, moisture may seep in, and after the moisture evaporates, a certain amount of air gap can form between the brake pads and discs, resulting in a soft and ineffective braking sensation. Here are some additional details: 1. Precautions for Brake Fluid: Summer high temperatures are a season prone to car accidents. If regular replacement is neglected, it may lead to brake failure or the bursting of brake fluid lines. Therefore, car owners should not take this lightly. If the braking feels inconsistent during normal driving, the brake fluid should be replaced promptly. Before replacement, clean the braking system thoroughly with alcohol. 2. Differences in Brake Fluid: Do not mix different types or brands of brake fluid. Due to differing formulations, mixing brake fluids can degrade their performance. If the brake fluid absorbs moisture or contains impurities, it should be replaced or filtered immediately; otherwise, it may cause insufficient braking pressure and affect braking performance. This is particularly important in the generally humid climate of southern China.
I just had the same experience. After the last maintenance, the brake pedal felt like stepping on cotton! The veteran mechanic taught me to first press the brake pedal 20 times in a row to reset the system. If it still feels soft, then check for air in the system. Remember to ask the repair shop to use equipment to completely remove all tiny air bubbles from the brake lines—manual bleeding often isn't thorough enough, which can cause this issue. The worst-case scenarios are air getting into the system during the brake fluid change or old fluid not being fully flushed out. Both situations require re-bleeding the system. My car had to go back for a second bleeding before the pedal feel returned. Now the brakes respond instantly with just a light touch. I suggest going back to the shop immediately to check the seals and brake line clamps.
As a mechanic with twenty years of experience, the three most common reasons for brakes becoming soft after an oil change are: air not being fully bled out, oil pipe joint leakage, and new oil being contaminated by old oil. Try pressing the brake pedal when the car is cold—if the pedal gets harder the more you press it, it's likely air residue; if it remains soft, it might be a pipe leakage. I strongly recommend rechecking the sealing ring at the brake master cylinder's oil inlet and the torque of the bleeder bolts on the wheel cylinders. Last time, a client had the same issue, and it turned out to be a slow leak caused by an apprentice not tightening the drain screw properly. This situation is very dangerous and must be addressed promptly.
