how to fix a coolant leak in my BMW 3 Series F30/F31 (2012-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the engine is cool and disconnect the battery.
• Place a drain pan under the vehicle to catch any leaking coolant.

2. Identify the Source of the Leak

• Coolant Reservoir: If cracked, replace the reservoir.
• Hoses: If damaged, remove the affected hose by loosening the clamps and replace with new hoses.
• Water Pump: If leaking, drain coolant, remove the water pump, and replace with a new one. Ensure to replace the gasket.
• Radiator: If damaged, remove the radiator by disconnecting the hoses and mounting bolts. Replace with a new radiator.
• Engine Block/Cylinder Head: If there are signs of a blown head gasket, perform a compression test and replace the gasket if necessary.

3. Reassemble and Refill

• Reconnect all hoses and components, ensuring all clamps are tight.
• Refill the cooling system with the appropriate type of coolant (BMW-approved).
• Use a funnel to prevent spills and ensure proper filling.

4. Bleed the Cooling System

• Start the engine with the radiator cap off to allow air to escape.
• Turn the heater on to maximum heat.
• Monitor the coolant level and add more coolant as necessary until no air bubbles are present.