- Insufficient amount of coolant in the system ("Weekly check").
- Thermostat malfunction (chapter 3).
- Clogged radiator or radiator grille (chapter 3).
- Malfunction of the electric radiator cooling fan or viscous coupling (chapter 3).
- Coolant temperature sensor malfunction (chapter 3).
- Air lock in the cooling system (chapter 3).
- The radiator cap is faulty (chapter 3).
Hypothermia
- Thermostat malfunction (chapter 3).
- Coolant temperature sensor malfunction (chapter 3).
- Viscous coupling failure (chapter 3).
External coolant leak
- Damage to hoses or clamps (chapter 1).
- Leak through the radiator or heater heat exchanger (chapter 3).
- The radiator cap is faulty (chapter 3).
- Leak through the internal seal of the coolant pump (chapter 3).
- Leak through the seal of the joint between the pump and the cylinder block of the cooling system (chapter 3).
- Liquid boiling due to overheating (chapter 3).
- Leak through the radiator cap (chapter 3).
Internal coolant leak
Corrosion
- Rare replacement of fluid and flushing of the cooling system (chapter 1).
- Unregulated composition of coolant or inappropriate type of antifreeze ("Weekly checks").
(The original material is located on the website: BMWMAN)