my BMW 3 Series G20/G21 (2019-2024) is leaking coolant, where should I check first?

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the engine is cold and the vehicle is parked on a flat surface.
• Wear safety gloves and goggles.

2. Locate the Leak

• Use a flashlight to inspect the areas identified during the diagnostic steps.
• If necessary, use a dye test kit to pinpoint the leak more accurately.

3. Repair or Replace Affected Components

A. Coolant Reservoir

• If the reservoir is cracked:
  1. Disconnect the negative battery terminal.
  2. Drain coolant from the reservoir.
  3. Remove the reservoir by disconnecting any attached hoses.
  4. Install the new reservoir and reconnect hoses.

B. Hoses

• For damaged hoses:
  1. Remove the affected hose clamps using pliers.
  2. Replace with a new hose of the same size and type.
  3. Reattach the clamps securely.

C. Water Pump

• If the water pump is leaking:
  1. Drain the coolant from the system.
  2. Remove the serpentine belt by releasing tension with a wrench.
  3. Unbolt the water pump from the engine block.
  4. Clean the mounting surface and install a new water pump with a new gasket.
  5. Reinstall the serpentine belt and refill coolant.

D. Radiator

• If the radiator is leaking:
  1. Drain the coolant from the system.
  2. Disconnect the upper and lower radiator hoses.
  3. Remove any mounting bolts securing the radiator.
  4. Install the new radiator, reattach hoses, and refill coolant.