Operation of the engine cooling system (Renault Symbol 1)

Cold coolant flows through the lower radiator hose to the water pump, which directs it to the water jacket of the cylinder block, the channels in the cylinder head and the heater radiator. After the block, combustion chambers and valve seats have cooled, the heated liquid goes to the lower thermostat valve, which is closed until the liquid is warmed up, then to the heater radiator and back to the water pump. When the engine is cold, the coolant does not get into the main radiator, which helps the engine warm up to operating temperature faster.

When the coolant reaches 89°C, a valve opens in the thermostat and the liquid enters the radiator, installed under the oncoming air flow in front of the car. The cooled liquid repeats the above cycle. If necessary, (in hot weather, when driving at low speed) additionally, an electric fan is switched on, which provides enhanced cooling of the liquid.

The cooling system uses a fluid based on ethylene glycol - it is most suitable for systems with components made of different metals. The fluid should always be replaced at the prescribed mileage interval. This is necessary not only to maintain its anti-freeze properties, but also because over time, anti-corrosion additives lose their properties and metal oxidation products form in the cooling system, polluting it and impairing engine cooling.



The diagram of the engine cooling system is shown in Fig. 3.79.