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Home >> BMW >> 2021 >> 840i xDrive 2D Convertible >> Repair and Diagnosis >> Engine Mechanical >> Cooling System (Mechanical) >> Cooling System -- Repair (G14, G15, & G16) >> 17 00 Coolant >> 17 00 009 Check the cooling system for watertightness with the special tool (with tester) (840i and 840i xDrive coupe/convertible/Gran Coupe sedan) >> Check the high-temperature cooling system for watertightness

Check the high-temperature cooling system for watertightness

WARNING: Hot surfaces  .
Risk of burning! 
  • Perform all work only on components that have cooled down.
G14192855Courtesy of BMW OF NORTH AMERICA, INC.
NOTE: TECHNICAL INFORMATION 
If the described test step is not completed successfully: repeat test step twice. Only replace the sealing cap after three tests with an incorrect opening pressure  .
When driving at high ambient temperatures, the design may cause the pressure relief valve in the sealing cap to open slightly and air to leakage together with dissolved coolant. This coolant vapor condenses on the surface of the coolant expansion tank and leaves traces of coolant when the vehicle has cooled down. These traces of coolant do not indicate whether the sealing cap is defective or not.
Leakage coolant vapors when the vehicle is at standstill may cause the pressure relief valve to stick to the sealing cap. This may cause an incorrect opening pressure.
G14192856Courtesy of BMW OF NORTH AMERICA, INC.
G14192673Courtesy of BMW OF NORTH AMERICA, INC.