General description and precautions (Peugeot Eurovans 806)

The liquid circulating in the cooling system removes heat from the engine, cooling in the radiator and also heating the interior. The coolant used is a product with anti-corrosion and frost-protective properties.

Forced circulation of the coolant is achieved by means of a water pump, which is driven by the timing belt. The water pump forces coolant into a fairly large number of channels and hoses.

Cooling of the heated liquid is provided by a radiator with a sufficiently large liquid distribution area. Cooling of the liquid in the radiator occurs due to the oncoming air flowing around the cooling fins of the radiator. When the engine load increases and, accordingly, heat transfer increases, the liquid is additionally cooled by an electric radiator fan. On vehicles with diesel engines, as well as those equipped with air conditioning, two fans are installed. The radiator fan is switched on by a thermal switch located on the bottom of the radiator.

To ensure that the coolant quickly reaches the required operating temperature, the cooling system is divided into small and large circuits. The large coolant circulation circuit is activated by a thermostat, which is a thermoelement filled with wax and equipped with a spring that ensures the necessary movement of the valve plates, thereby opening or closing the large circuit.

During the engine warm-up period, a valve controlled by a thermostat closes the access of coolant to the radiator. The bypass valve immediately directs the flow of coolant to the water pump, which forces coolant into the engine cooling jacket. Circulation of coolant in such a circuit promotes rapid warming up of the engine.



As soon as the coolant temperature rises to 85-100°C, the thermostat gradually opens the large circuit valve, directing the liquid into the radiator. The cold liquid from the radiator mixes with the hot liquid from the engine, and only after this does the liquid again enter the engine cooling jacket. This way the hot engine is not exposed to cold coolant.

To increase the cooling effect, as the coolant heats up, increased pressure, reaching almost 1.0 bar, is created in the cooling system. This pressure is maintained by a corresponding valve in the expansion tank cap. Increased pressure in the system increases the boiling point of the coolant. When the permissible pressure level in the system is exceeded, the release valve on the expansion tank cap opens and the excess pressure is released.

Over time, the anti-corrosion effect of the coolant decreases, so the coolant itself must be replaced with a new one.

The cooling circuit of vehicles with diesel engines includes an oil cooler, installed between the oil filter and the cylinder block. The oil radiator is connected to the cooling system by two hoses. A diesel fuel heater unit is located on the coolant outlet pipe, which facilitates starting the diesel engine in cold weather.

Caution! The radiator fan may turn on even when the engine is off. This is especially possible immediately after turning off the engine. For this reason, care must be taken when working in the engine compartment near the fan.

(The source is located on the website PEUGEOTBOOK)