1. Locate the Vacuum Leak:
- With the engine turned off, listen for the hissing sound near the brake pedal.
- Use a smoke machine or spray some soapy water around the vacuum lines and connections to identify the exact location of the leak.
2. Inspect Vacuum Lines:
- Check all the vacuum lines and connections for cracks, tears, or loose fittings.
3. Replace the Faulty Vacuum Line:
- If you find a damaged vacuum line, replace it with a new one of the same size and type.
4. Check Other Related Components:
- While inspecting the vacuum lines, also check the brake booster, master cylinder, and other vacuum-operated components for any abnormalities.
5. Test the Repair:
- After replacing the vacuum line, start the engine and check if the hissing sound has disappeared, and the engine is idling smoothly.
6. Verify Brake Function:
- Once the vacuum leak is fixed, perform a few brake tests to make sure the brakes are functioning properly.
Note: If the vacuum leak was causing the rough idling and brake pedal hissing symptoms, replacing the faulty vacuum line should resolve the issue. However, if the problem persists or if you notice any other abnormalities, it is recommended to consult a professional mechanic for further diagnosis and repair.
