The circulation of the coolant is regulated by a thermostat. Until the engine is warmed up, the coolant circulates only in the cylinder head, in the cylinder block and in the heater radiator.
As the temperature increases, the liquid cooling system thermostat opens and directs the flow of coolant to the radiator. The coolant is supplied by a water pump.
The coolant passes through the radiator from top to bottom and is cooled by the oncoming air passing through the cooling fins.
For additional cooling of the liquid, an electric radiator fan is installed.
As soon as the coolant temperature goes beyond certain limits, the relay turns on the mentioned electric fan.
As the coolant temperature drops, the electric fan switches off.
The expansion tank in cars with petrol engines produced before 5/99 is located in the engine compartment on the right side, if you look in the direction of travel, directly next to the radiator.
In cars with petrol engines produced from 6/99, as well as in cars with diesel engines, the expansion tank is located on the right stiffener and is connected to the radiator by two hoses.
It functions as a coolant reservoir and accumulates the coolant that increases in volume when heated, releasing it back into the circulation circuit after the engine has cooled.
Publication taken from an online resource MercedesMAN.ru
The coolant in the system is replenished through the expansion tank.
Attention! When working on the cooling system, be sure to remember that coolant must not come into contact with the V-belt. The ethylene glycol contained in the coolant can damage the belt fabric so much that it will break after a certain period of use, which in turn will lead to serious damage to the engine.
Caution! Before starting work in the engine compartment, especially near the radiator fan, be sure to remove the fuse or disconnect the power plug of the electric fan. The electric fan may turn on automatically due to the heat accumulated in the engine compartment and if the ignition is not switched off. Risk of injury or damage!