why does my BMW 3 Series E90/E91 (2005-2012) overheat in heavy traffic

Solution

1. Preparation

• Gather necessary tools and safety equipment.
• Ensure the engine is cool before starting work.
• Disconnect the battery to prevent electrical shorts.

2. Coolant Inspection and Replacement

• Tools Required: Coolant funnel, drain pan, wrench set
• Check and top off coolant if low. If coolant is contaminated or old, proceed to replace.
  • Sub-steps:
    • Place a drain pan under the radiator.
    • Open the drain valve or remove the lower radiator hose to drain the coolant.
    • Close the drain valve or reinstall the hose after draining.
    • Refill the system with a 50/50 mixture of BMW-approved coolant and distilled water.

3. Replace Cooling Fan

• Tools Required: Screwdriver set, socket set
• If the cooling fan is not functioning correctly, it may need replacement.
  • Sub-steps:
    • Disconnect the electrical connector from the fan.
    • Remove the mounting screws securing the fan to the radiator shroud.
    • Lift the fan assembly out and replace it with a new fan.
    • Reconnect the electrical connector and secure the fan in place.

4. Radiator Inspection and Cleaning

• Tools Required: Hose for cleaning, soft brush
• Inspect and clean the radiator to ensure proper airflow.
  • Sub-steps:
    • Remove any debris or dirt from the exterior of the radiator using a soft brush.
    • Use a garden hose to flush any remaining debris from the fins of the radiator.
    • Verify that the air passages are clear and reassemble any components removed.

5. Test Water Pump Function

• Tools Required: Socket set, wrench
• If the water pump is suspected of failure, it should be tested or replaced.
  • Sub-steps:
    • Remove any components obstructing access to the water pump.
    • Inspect for leaks or unusual noises while the engine is running.
    • If necessary, replace the water pump by removing the mounting bolts and disconnecting hoses.