The coolant circulates under the action of a pump, which, like other additional units, is driven by a belt drive from the crankshaft.
To regulate the thermal regime of the cooling system, a thermostat is located in a special housing. Depending on the required degree of cooling, the thermostat regulates the circulation of liquid through the radiator. There are three phases of thermostat operation: warming up (coolant does not enter the radiator), Work mode (variable fluid circulation through the radiator) and maximum cooling (all fluid passes through the radiator).
Pic. 134. Viscous coupling fan cooling system (cross section): 1 - body; 2 - cover; 3 - contact pin; 4 - bearing sleeve; 5 - bimetallic element; 6 - valve; 7 - sealing ring; 8 - ball bearing; 9 - drive disk; A - preliminary chamber; B - working chamber
For more efficient cooling of the liquid passing through the radiator, a fan is installed behind it. It supplements the cooling effect of the oncoming air flow while driving, driving it through the radiator. The fan is driven through a viscous coupling located in the center of the impeller and controlled depending on the temperature by a bimetallic spring. A special silicone filling in the viscous coupling drives the fan when cooling is needed. When the engine is cold, the viscous coupling drive mechanism is open and the fan rotates at low speed. When the operating temperature rises to 85–90°C, the viscous coupling mechanism is activated and the fan and engine speeds become equal. On fig. 134 shows the internal structure of this mechanism.
Low coolant level
Pic. 121. Oil pressure warning lamp
Pic. 135. Location of the expansion tank of the cooling system
If the warning lamp in the instrument cluster comes on when accelerating the vehicle or when cornering (to the right of the oil pressure lamp shown in fig. 121), the amount of coolant in the system is insufficient. In this case, you should stop the car and add coolant through the filler hole of the expansion tank. On fig. 135 shows a radiator expansion tank, which is often opaque. Therefore, to check the fluid level, you need to unscrew the plug (the hot engine must cool down, the coolant temperature must not exceed 50°C) and add liquid. If more than 0.75 liters is required for topping up, the system connections must be checked. With a high degree of probability, we can assume that there are coolant leaks in it.
There is a coolant level sensor in the reservoir. If the level is below the MIN·mark, the sensor contacts close and the control lamp lights up in the instrument cluster. Through the branch pipe leaving the bottom of the expansion tank, the coolant enters the system or, conversely, back into the tank, depending on the volume of liquid filled. The top pipe serves for ventilation. The cooling system is self-ventilated through a ball valve in the thermostat. The expansion tank cap regulates the pressure in the system.
Antifreeze is poured into the cooling system, the volume of which depends on the type of engine and the configuration of the car with air conditioning.
The coolant pump is secured with four bolts through an O-ring on the cylinder block. The pump has not been repaired.