What Are the Common Causes of Brake Vacuum Pump Failure?
3 Answers
Here are the common causes of brake vacuum pump failure: 1. The vacuum pump temperature is too high: The temperature of the pumped gas is too high. Allow the gas to cool before it enters the vacuum pump. Ingesting hard objects causes wear to the vacuum pump body. Disassemble the vacuum pump to remove the hard objects, repair or replace the scratched components, and ensure sufficient cooling water flow. Increase the cooling water flow if necessary. Improper assembly causes rotor shaft displacement, leading to unilateral wear. Disassemble and inspect, then reassemble properly. 2. Issues with the vacuum pump oil: The oil level is too low. Fill the oil to the center line of the oil gauge. The oil is contaminated or deteriorated. Replace with new oil. The oil grade does not match. Replace with the specified grade of vacuum pump oil. The oil path is blocked, and the vacuum pump chamber does not maintain an adequate oil level. Check the oil path and the oil valve's intake, ensuring the oil path is clear. 3. The vacuum pump itself leaks: The sealing ring leaks. Inspect the sealing condition of all sealing parts and replace damaged sealing rings. The gas ballast valve gasket is damaged or not tightened. Replace the gasket and tighten the gas ballast valve. The exhaust valve plate is damaged, causing poor sealing. Replace the valve plate. The interference of the vacuum pump partition plate during installation is too large, causing deformation of the vacuum pump chamber and leakage. Repair the vacuum pump chamber or replace it. Leakage occurs due to poor end-face oil sealing of the vacuum pump. Disassemble the end cover, check for debris or unevenness, and clean or repair as needed.
As someone with some knowledge of automotive structures, I've found that brake vacuum pump issues often stem from internal component wear and aging. The rubber seals inside the pump harden and crack over time, leading to vacuum leaks and reduced brake assist. Additionally, cracks in vacuum lines, loose connections, or poor electrical contacts in electric pumps causing unstable current supply can all interrupt vacuum generation. Dirt entering from the intake system clogging pump chambers and affecting operation is another common pitfall. In daily driving, frequent hard braking accelerates wear on these components. I recommend regularly checking these areas and having a mechanic inspect the lines and pump condition every 10,000 kilometers to ensure safety and peace of mind.
Last time when my car's brake assist suddenly worsened, the technician said the main cause was a vacuum pump issue. The most common problems are aging or cracked tubes or loose connections causing air leaks and insufficient suction, making driving particularly strenuous. It's also common for internal seals to crack or deform after prolonged use, especially in vehicles that have been driven for several years, as components naturally fatigue. Contaminants entering the pump and jamming the piston are not uncommon either, possibly due to inadequate maintenance. That time, I spent some money on new parts, and since then, I've made sure to check frequently and address any unusual brake feel promptly. I've developed a habit of inspecting every six months to avoid trouble on the road.
