What to do if the Baojun 730 brake master cylinder is still leaking after replacement?
2 Answers
If the Baojun 730 brake master cylinder is still leaking after replacement, it may be due to a fault in the vacuum booster pipe or the vacuum booster itself, which is unrelated to the brake master cylinder. It is necessary to visit a repair shop or 4S store for inspection. The main function of the brake master cylinder is to provide brake assistance, which only takes effect after the vehicle's engine is started. Symptoms of a faulty brake master cylinder include: 1. Oil leakage at the connection between the brake master cylinder and the vacuum booster or at the limit screw. 2. Poor or ineffective braking even when the brake pedal is fully depressed. 3. The brake pedal feels too soft when pressed. 4. The vehicle pulls to one side after braking. 5. Sudden brake failure. 6. The brake pedal does not return or returns slowly.
As a mechanic who frequently works on brake systems, I've handled many similar cases. If the master cylinder replacement still results in air leaks, it's usually not the master cylinder itself but other installation issues. Possible causes include loose or cracked tubing connections (e.g. improperly tightened copper pipes/rubber hoses allowing air escape), or faulty wheel cylinders - especially with rear drum brakes or worn front calipers. Contamination during installation (uncleaned grease residues or reused old parts) may also compromise sealing. Air leaks cause spongy brake pedals, creating driving hazards. My recommendation: First inspect all connection points for hissing sounds or perform a soapy water bubble test to locate leaks. If unresolved, seek professional repair immediately. Safety comes first - new parts don't guarantee problem resolution, thorough troubleshooting is essential.
