Why does the brake suddenly become very hard to press when reversing?

[CaydenMarie]

When the brake suddenly becomes very hard to press while reversing, it is usually due to a leak or malfunction in the brake booster pump. Here are the detailed explanations regarding the reversing brake: 1. Fault Details: In case of an unexpected brake issue, it is important to repeatedly press the brake pedal several times. This action applies pressure to the braking system where air might be trapped in the oil pipes, and with repeated pressing, there is a chance to restore the braking force. 2. Precautions: If distance permits, try to use intermittent braking (pump the brakes). This method can reduce wear on the vehicle's brake pads and tires. Additionally, always check the rearview mirror. If there is a vehicle approaching from behind without slowing down, turn on the hazard lights and prepare to change lanes in advance.

[VonStella]

I've experienced several instances where the brake pedal suddenly became as hard as a rock when reversing, making it impossible to press. That's when I realized the vacuum booster might be malfunctioning, because during reversing, the engine speed is low, leading to insufficient vacuum pressure and loss of power assist. If there's a brake fluid leak or air bubbles in the hydraulic system, it can also cause the pedal to harden; likewise, if the booster pump's hose has cracks causing air leaks, reversing is when the issue is most likely to surface. At the time, I immediately stopped the car, shifted to neutral, and tried pressing the pedal hard a few times to see if it would recover, but it's best not to continue reversing—it's very dangerous. Since then, I've developed a habit of gently testing the brakes before every drive, especially before reversing, to ensure everything is functioning properly.

[DeFelix]

As an experienced driver of many years, hard brakes when reversing is a serious issue that shouldn't be ignored. Potential causes include vacuum system failure, such as a broken booster or loose/leaking connecting pipes; and insufficient brake fluid, possibly due to ruptured hoses or air entering the system. I remember encountering this when reversing on a slope - nearly scraped the wall and only stabilized the car by using the handbrake. If this happens, immediately stop operating, turn off and restart the engine - sometimes this provides temporary relief. Safety comes first - contact a repair shop immediately for thorough inspection. Regular maintenance checks of the vacuum pump and brake fluid condition by mechanics can prevent this issue.

[CorbinAnn]

I work in automotive repair, and hard brakes when reversing are commonly caused by a lack of vacuum boost. This happens because the engine runs at a lower RPM when reversing, leading to insufficient vacuum supply. Issues like brake fluid leaks or air leaks can exacerbate this problem. Check if the booster hose is properly sealed and if the brake fluid reservoir level is low. Emergency solution: After stopping, repeatedly pressing the brake pedal a few times might restore some boost, but the fundamental solution is professional inspection and repair. Regular maintenance can prevent most issues.