Engine cooling system malfunctions, their causes and solutions
| Cause of malfunction | Method of elimination |
| The engine gets very hot | |
| Low coolant level in the expansion tank Thermostat is faulty (thermostat valve stuck in closed position) The water pump is faulty The radiator core is clogged with dirt and insects Radiator pipes, hoses and engine cooling jacket are clogged with scale and silt deposits The radiator electric fan does not turn on due to a break in the sensor electrical circuit, failure of the sensor, relay or fan electric motor Damage to the valve in the expansion tank cap (is constantly open, which is why the system is under atmospheric pressure) | Add coolant to the expansion tank Replace Thermostat Check the water pump and replace it if faulty Wash the outside of the radiator core Flush the engine cooling system and fill with fresh coolant Check and repair the electrical circuits of the radiator electric fan. If necessary, replace the sensor, relay or radiator fan assembly Replace the expansion tank cap |
| The engine overheats, cold air comes from the heater | |
| Excessive loss of coolant level due to leakage or damage to the cylinder head gasket, causing vapor lock in the engine water jacket | Fix the coolant leak. Replace a damaged cylinder head gasket |
| The engine takes a long time to warm up to operating temperature, the thermal regime during movement is unstable | |
| Thermostat is faulty (thermostat valve stuck in open position) | Replace Thermostat |
| Constant decrease in coolant level in the expansion tank | |
| Radiator leaking The expansion tank is leaking Coolant leakage through leaky connections of pipes and hoses The water pump seal is damaged The sealing gasket of the water pump housing is damaged The cylinder head mounting bolts are not tightened sufficiently (during prolonged parking on a cold engine, a coolant leak appears at the joint between the cylinder head and the cylinder block; in addition, traces of coolant may appear in the engine oil) The heater radiator (stove) is leaking | Replace the radiator Replace the expansion tank Tighten the hose clamps Replace the water pump Replace the water pump housing gasket Tighten the cylinder head mounting bolts to the specified torque (see "Replacing the cylinder head gasket") Replace the heater radiator (stove) |