- Insufficient amount of coolant in the system ("Weekly check").
- Thermostat failure (chapter 3).
- Clogged radiator or 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).
- Faulty radiator cap (chapter 3).
hypothermia
- Thermostat failure (chapter 3).
- Coolant Temperature Sensor Malfunction (chapter 3).
- Viscous coupling failure (chapter 3).
External coolant leak
- Damaged hoses or clamps (Chapter 1).
- Leakage through radiator or heater heat exchanger (chapter 3).
- Faulty radiator cap (chapter 3).
- Leakage through the inner seal of the water pump (chapter 3).
- Leakage through the seal of the joint between the pump and the cylinder block of the cooling system (chapter 3).
- Boiling off liquid due to overheating (chapter 3).
- Leak through radiator cap (chapter 3).
Internal coolant leak
- Leakage through the cylinder head gasket (chapter 2).
- Crack in the cylinder head or cylinder liner (chapter 2).
Corrosion
- Infrequent fluid changes and flushing of the cooling system (Chapter 1).
- Irregular coolant composition or wrong type of antifreeze ("Weekly checks").