1. Check the coolant level (see «Checking the levels of technical fluids»).
2. Check the condition of the radiator of the cooling system. Its cells should not be clogged with dirt, especially the radiator area opposite the air intake windows in the front bumper. If the radiator is dirty, it should be flushed and blown out with compressed air away from the engine.
For better cleaning, it is advisable to dismantle the radiator (see «Radiator of the cooling system - replacement»).
3. We check the absence of fluid leakage from the drain fitting of the cooling system radiator, from the coolant temperature sensor, the connections of the rubber hoses of the cooling system, as well as their integrity. If there are signs of fluid leakage, it is necessary to tighten the connections (replace clamps) or replace damaged items.
4. We check the absence of fluid leakage through the coolant pump seal. For clarity, shown on the removed pump, when checking on a car, it is necessary to remove the front cover of the timing belt (see «Timing belt - condition check, tension adjustment and replacement»).
If there is a leak, the water pump must be replaced (see «Coolant pump - replacement»).
Comment. The need to replace the pump can also be caused by a malfunction of its bearing. In this case, a loud noise will be heard during engine operation. To confirm it is necessary after removing the timing belt (see «Timing belt - condition check, tension adjustment and replacement») check ease of rotation (there should be no seizures) and lack of backlash of the pump gear in the longitudinal and transverse directions.
5. We check the operation of the thermostat in the following order: we start the engine and manually control the temperature of the upper radiator hose.
6. We check the inclusion of the electric fan of the cooling system. When the air conditioning system is off (or if it's not installed) the electric fan should turn on at the first speed when the temperature reaches 100°C, turn off at a temperature of 95°C. When the air conditioning system is turned on (if it is installed) the electric fan should turn on at the first speed. If the electric fan does not turn on or one of the speeds does not turn on, it must be checked (see «Electric fans of the cooling system - check and replace»).
Comment. There may be a malfunction of the thermostat, in which its valve starts to open on time, but in the end it does not open completely, which can also lead to overheating of the engine. It is possible to check the completeness of the thermostat valve opening only after removing it from the car (see «Thermostat - check and replacement»). If the thermostat valve opens fully, then the most likely cause of overheating is a faulty coolant pump (see «Coolant pump - replacement»).
7. We check the absence of compression of the cooling system hoses when the engine cools down and their excessive hardening when the engine is running, when the coolant temperature is more than 70°C. In the presence of these malfunctions, the cap of the expansion tank of the cooling system should be replaced.
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