Why is the brake of the SouEast DX7 so hard?

[VanCourtney]

The reasons for the hard brake in the SouEast DX7 include stepping on the brake before turning off the engine and brake booster pump failure. Stepping on the brake before turning off the engine: The car's braking system functions at its best when the engine is running, and the brake booster pump is the key component that amplifies the force applied to the brake pedal. When the engine is off, the brake booster pump loses its function. Typically, stepping on the brake pedal three times will deplete the remaining vacuum force, making the brake feel hard due to the lack of assistance from the brake booster pump. Solution: In this case, simply restart the engine and try pressing the brake pedal firmly again. Once the engine is running, the brake booster pump will resume functioning, and the brake pedal will return to normal. Brake booster pump failure: If the car's brake booster pump is leaking or malfunctioning, and you haven't stepped on the brake pedal after turning off the engine, or if you find the brake pedal hard to press while driving, it is likely due to a faulty brake booster pump, a vacuum tube leak, or blockage. Solution: If this issue is noticed before driving, it is advisable not to proceed and to have the car inspected at a repair shop immediately. If the problem arises while driving, remain calm, reduce speed, and come to a stop. Try pressing the brake pedal multiple times to see if braking can be restored. Applying more force usually helps generate braking power.

[JosiahDella]

My Soueast DX7's brake pedal has become extremely stiff recently, requiring a lot of force to press down. After checking some information, I found there could be several reasons: The most common issue is air leakage or failure in the vacuum booster pump, which is responsible for making the brake pedal easy to press - if it's broken, the entire assembly needs replacement. Another possibility is if the vacuum hose in the engine compartment connecting to the intake manifold is cracked or if its sealing ring has aged, causing air leakage and loss of power assistance. Additionally, if the brake fluid has deteriorated or air has entered the pipelines, the hydraulic system will become stiff. A more troublesome issue could be the brake master cylinder piston sticking, which requires disassembly for inspection. Honestly, such brake problems shouldn't be delayed. I recommend going to a repair shop immediately to check the vacuum pressure with a diagnostic computer - don't wait until something serious happens to regret it.

[JaceMarie]

A colleague's DX7 also experienced brake stiffness before. Focus on checking these three aspects: First, check if the vacuum pump is leaking—start the engine and remove the vacuum hose to listen for any hissing sounds. Second, inspect the brake fluid reservoir; low fluid level or contamination can affect braking force. Third, verify if the one-way valve behind the brake master cylinder is malfunctioning—even a clogged small component can cause power assist failure. Additionally, if the issue occurs right after car washing or during rainy weather, it might be due to temporary stiffness caused by ice formation on the brake disc surface. Friendly reminder: Such faults are difficult to handle yourself. Visit a 4S shop to test the booster pressure with a vacuum gauge—repair costs are often cheaper than expected.

[DelOscar]

After researching such faults, the DX7's hard brake pedal is usually caused by abnormal vacuum system. The booster operates on engine negative pressure. When the throttle body has severe carbon buildup or air leakage, the vacuum drops below 30 kPa, resulting in a stiff pedal. There are also cases where the brake hose is deformed by the chassis guard plate, causing increased hydraulic pressure. In rare cases, excessive brake pad wear leads to longer wheel cylinder stroke and poor pedal feel. As a reminder for drivers who frequently travel on mountain roads, continuous braking can cause booster overheating and temporary stiffness, which recovers after cooling. It's recommended to replace brake fluid regularly, with two years being the safest interval.