Cooling System Troubleshooting

Engine overheating
1 Coolant level is low (refer to Maintenance and Adjustments).
2 Radiator core is clogged or radiator grille is blocked (refer to Cooling System and Heating).
3 Thermostat is faulty (refer to Cooling System and Heating).
4 Coolant passage is blocked by an air pocket (refer to Maintenance and Adjustments).
5 Radiator cap seal is not sealing properly (refer to Cooling System and Heating).
6 Circuit of the cooling fan is faulty (refer to Cooling System and Heating).
7 Cooling fan blades are mechanically damaged (refer to Cooling System and Heating).
8 Coolant temperature sensor readings are inaccurate (refer to Cooling System and Heating).
9 Ignition timing is out of adjustment (refer to Engine Electrical System).

Engine overcooling
1 Thermostat is faulty (refer to Cooling System and Heating).
2 Coolant temperature sensor readings are inaccurate (refer to Cooling System and Heating).
3 Circuit of the cooling fan is faulty (refer to Cooling System and Heating).

External coolant leaks
1 Coolant hoses or hose clamps are mechanically damaged or deteriorated due to aging (refer to Maintenance and Adjustments and Cooling System and Heating).
2 Water pump is faulty (refer to Cooling System and Heating).
3 Coolant is leaking from the radiator or expansion tank (refer to Cooling System and Heating).
4 Drain or bleed plugs of the cylinder block water jacket are damaged (refer to Engine).
5 Radiator cap is faulty (refer to Cooling System and Heating).
6 Coolant has boiled as a result of overheating (refer to Cooling System and Heating).

Internal coolant leaks
1 Cylinder head gasket is blown (refer to Engine).
2 Cylinder head or cylinder block is cracked (refer to Engine).

Coolant loss
1 Excessive amount of coolant has been added to the system (refer to Maintenance and Adjustments).
2 Coolant is boiling off due to overheating (refer to Cooling System and Heating).
3 External or internal coolant leaks are present (refer to Cooling System and Heating).
4 Radiator cap is faulty (refer to Cooling System and Heating).

Coolant circulation is disturbed
1 Water pump is faulty (refer to Cooling System and Heating).
2 Coolant passage is blocked (refer to Maintenance and Adjustments and Cooling System and Heating).
3 Thermostat is stuck closed (refer to Cooling System and Heating).