why is my Volkswagen Golf MK7 (2015-2019) losing coolant but no visible leaks?

Solution

1. Preparation

• Gather tools and parts.
• Ensure the engine is cold before beginning work.
• Disconnect the battery to prevent electrical issues.

2. Pressure Test the Cooling System

• Tools Required: Coolant pressure tester
• Sub-steps:
  1. Remove the radiator cap and attach the pressure tester.
  2. Pump the tester to the recommended pressure (typically 15-20 psi).
  3. Observe for any drop in pressure over time, indicating a leak.

3. Inspect the Engine Oil

• Tools Required: Oil dipstick
• Sub-steps:
  1. Remove the oil dipstick and check for a milky or frothy appearance.
  2. If contamination is present, prepare for further investigation into the head gasket or internal engine issues.

4. Check for Exhaust Gases in Coolant

• Tools Required: Combustion leak tester
• Sub-steps:
  1. Follow the manufacturer’s instructions to connect the tester to the coolant reservoir.
  2. Start the engine and monitor the tester for color change, indicating exhaust gases present in the coolant.

5. Replace Faulty Components

• If any leaks or contamination are found:
  1. Replace the head gasket if needed, following specific torque specifications (usually around 25-30 Nm).
  2. Replace any damaged hoses or the radiator as required.
  3. Refill coolant using the manufacturer-recommended type (usually G12 or G13 coolant).

6. Reassemble and Refill

• Sub-steps:
  1. Reattach any removed components and ensure everything is secured.
  2. Refill the cooling system with the appropriate coolant mixture.
  3. Bleed the system to remove any air pockets.