What Causes the Brake to Suddenly Become Hard and Unpressable During Startup?
2 Answers
The reasons why the brake suddenly becomes hard and unpressable during startup are: 1. The owner stepped on the brake several times after turning off the engine, causing the vacuum in the brake booster pump to disappear. Without the booster assistance, it becomes difficult to press the brake pedal. Additionally, the booster pump does not operate when the engine is off. The owner simply needs to attempt restarting the engine and press the brake pedal firmly. Once the engine starts, the brake will return to normal. 2. There may be air leakage in the vehicle's brake booster pump or a component malfunction. The car's brake pedal is located below the steering wheel. Pressing the brake pedal activates the brake linkage, which applies pressure and transfers it to the brake shoes on the brake drum, clamping the brake rotor and causing the car to slow down or stop.
I've been driving for decades and have encountered the issue of the brake pedal suddenly becoming as hard as a rock and unable to be pressed down during startup several times. The main reason is the lack of vacuum in the vacuum booster pump. After the engine is turned off, if you press the brake pedal a few more times, the vacuum reserve is depleted, leading to brake failure at the moment of startup. The vacuum booster relies on the vacuum force generated by the engine to help you press the brake pedal easily. Once the vacuum fails, you can only rely on brute force. It's essential to promptly check the brake fluid level or whether there's any air leakage in the vacuum lines, such as aging and cracking of the lines or damage to the booster pump diaphragm—these are common faults. Safety first! Before starting the engine each time, avoid pressing the brake pedal unnecessarily, and don't touch it after the engine is off. If the brake remains hard after starting, go to a professional repair shop immediately for inspection; otherwise, it's really dangerous on the highway. During regular maintenance, have the technician test the vacuum system function to avoid unexpected issues.
