why does my BMW 3 Series G20/G21 (2019-2024) make a hissing sound when turned off?

Solution

1. Preparation

• Tools Required: Socket set, screwdrivers, coolant catch pan.
• Ensure the engine is cool to avoid burns.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Repair Coolant System

1. Visual Inspection:

   • Check all hoses and connections for signs of wear or leaks.
   • Look for any cracks around the radiator or water pump.

2. Coolant Level Check:

   • If coolant is low, refill it with the appropriate type of coolant specified in the owner's manual.
   • If coolant was low, check for leaks and repair as necessary.

3. Radiator Cap Check:

   • Remove the radiator cap and inspect the rubber seal for cracks or deformation.
   • Replace the radiator cap if it shows signs of damage.

3. Inspect and Repair Vacuum Lines

1. Locate Vacuum Lines:

   • Trace the vacuum lines from the intake manifold to various components.

2. Inspect for Damage:

   • Look for any cracks, splits, or disconnections in the vacuum lines.

3. Replace Damaged Lines:

   • Cut and replace any damaged sections of the vacuum line with appropriate size replacements.