why is my BMW 3 Series G20/G21 (2019-2024) making a hissing sound

Solution

1. Preparation

• Gather tools and parts required for inspection and repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.

2. Inspect and Replace Vacuum Lines

• Sub-steps:
  • Locate and inspect each vacuum line for cracks or damage.
  • If damaged, remove the old vacuum line by disconnecting it from the fittings.
  • Measure and cut a new vacuum line to the correct length.
  • Install the new vacuum line securely, ensuring all connections are tight.

3. Check and Repair Intake Manifold

• Sub-steps:
  • Remove any engine covers to access the intake manifold.
  • Inspect the intake manifold for cracks or loose bolts.
  • Tighten any loose bolts to the manufacturer's torque specifications (usually around 10-15 Nm).
  • If cracks are present, replace the intake manifold with a new one.

4. Address Cooling System Issues

• Sub-steps:
  • Inspect the radiator and hoses for leaks while the engine is running.
  • If leaks are found, replace the damaged hose or radiator.
  • Refill the cooling system with the appropriate coolant mixture (usually a 50/50 mix of water and coolant) and bleed the system.