The cooling system is liquid-cooled, of the closed type, with forced circulation
It consists of the expansion tank, the coolant pump, the engine cooling jacket, the thermostat housing, the thermostat, the radiator with electric fan and the connecting hoses
The heater radiator, located in the vehicle cabin, and the heat exchanger (2.0 engine) are connected to the cooling system.
The system is filled with coolant through the neck of the expansion tank.
The expansion tank, secured in the engine compartment on the left mudguard cup, is made of semi-transparent plastic, which allows visual monitoring of the coolant level.
On the wall of the expansion tank the marks MAX and MIN are applied, between which the liquid level must be with a cold engine.
To the upper union of the tank the vapour discharge hose is connected, connecting the tank with the thermostat cover.
The filler hose of the expansion tank and the radiator outlet hose are connected by means of a plastic splitter to the hose of the inlet pipe of the coolant pump.
The tightness of the cooling system is ensured by the inlet and outlet valves in the cap of the expansion tank.
The outlet valve maintains an increased, compared with atmospheric, pressure in the system with a hot engine.
Due to this the boiling point of the liquid is raised, and the vapour losses are reduced.
The inlet valve opens when the pressure in the system decreases with a cooling engine.
If the cap is lost, it must not be replaced by a sealed cap without valves, even one suitable in size and thread — this will lead to an inadmissible increase of pressure in the cooling system (with a hot engine) and, as a consequence, to a leak of coolant from under the hoses.
The circulation of the liquid in the cooling system is ensured by the coolant pump, located at the right end of the cylinder block. The coolant pump is of the vane, centrifugal type.
The pump is rotated by the timing drive belt from the crankshaft pulley, and, on the 1.6 engine — by the toothed side of the belt, while on the 2.0 engine — by the reverse (flat) side of the belt.
The pump consists of the housing, a bearing assembly with a seal, the impeller and the drive pulley.
The liquid arrives at the pump through its inlet pipe, located on the front wall of the cylinder block.
From the pump the liquid under pressure enters the cooling jacket of the cylinder block, then into the cooling jacket of the cylinder head, and from there — to the thermostat housing, attached to the left end of the cylinder head.
The thermostat, located in the housing and closed by the cover, contributes to accelerating the warming up of the engine, to automatically maintaining its thermal regime within the given limits and regulates the amount of liquid passing through the radiator of the cooling system.
Inside the thermostat a metal bulb with a heat-sensitive filler is installed.
The bulb is hermetically closed by a rubber insert.
When heated, the filler melts and increases its volume, compressing the insert.
The rubber insert is deformed, the membrane flexes and moves the stem controlling the thermostat valve.
With an unwarmed engine the thermostat valve is closed and shuts off the union of the thermostat cover leading to the radiator of the cooling system.
In this case all the liquid, through the thermostat housing, enters the heater radiator, bypassing the radiator of the cooling system, and returns to the pump — the small circulation circuit.
Through the heater radiator and the heat exchanger (2.0 engine) the liquid circulates constantly and does not depend on the position of the thermostat valve.
As the engine warms up, at a liquid temperature of about 89 °C the thermostat valve begins to move, letting the liquid flow into the radiator of the cooling system.
At a temperature of 95±2 °C the thermostat valve opens fully, and the liquid enters the radiator of the cooling system, where it gives up heat to the ambient air.
The movement of the liquid through the engine cooling jacket and the radiator of the cooling system forms the large circulation circuit.
On the heater radiator outlet hose there is a union, and on the thermostat housing — a threaded plug for bleeding air from the cooling system when filling it with liquid.
The union on the hose is closed by a cap.
On the 2.0 engine, by means of two hoses connected to the unions of the plastic splitter (which also connects the filler hose, the radiator outlet hose and the hose of liquid supply to the pump pipe) the circulation of liquid through the engine heat exchanger is ensured.
The radiator of the cooling system is secured to the fan shroud.
The radiator consists of two vertically arranged plastic tanks, connected by aluminium tubes with cooling plates.
The liquid enters the radiator through the upper union in the right tank, and is discharged through the lower union in the left tank.
The radiator has no drain opening.
The electric fan is installed in the shroud, which is secured at the top to the upper crossmember of the radiator frame, and at the bottom — to the front suspension subframe.
With the rise of the coolant temperature the fan is switched on by command of the electronic engine control unit (ECU) through a relay.
On the fan shroud an additional resistor is installed.
When the coolant temperature reaches 99 °C, the ECU switches on the fan electric motor through the additional resistor, and the fan rotates at low speed.
When the liquid temperature drops to 96 °C, the fan switches off.
When the coolant temperature reaches 102 °C, the ECU switches on the electric motor, bypassing the resistor, and the fan rotates at high speed.
If the coolant temperature exceeds 118 °C, the engine overheating indicator lamp lights up in the instrument cluster.
The coolant temperature sensor is screwed into a threaded opening of the thermostat housing.
The sensor gives information to the temperature indicator in the instrument cluster, to the engine overheating indicator lamp and to the electronic engine control system unit.
Possible faults of the cooling system, their causes and methods of remedy
- Cause of the fault - Method of remedy
The engine overheats:
- - Low coolant level in the expansion tank - Add coolant
- - Thermostat faulty (valve stuck in the closed position) - Replace the thermostat
- - Water pump faulty - Replace the water pump
- - Radiator tubes, hoses and engine cooling hose clogged with scale and silt deposits - Rinse the cooling system and fill with fresh coolant
- - The electric fan does not switch on because of a break in the electrical circuits or failure of the sensor, relay or fan electric motor - Check and restore the electrical circuits. If necessary, replace the sensor, relay or fan as an assembly
- - Damage to the valve in the plug of the expansion tank (the valve is constantly open, because of which the system is at atmospheric pressure) - Replace the plug of the expansion tank
The engine overheats, cold air comes from the heater:
- - Excessive drop in the coolant level because of a leak or damage to the cylinder head gasket, which causes the formation of vapour locks in the engine water jacket - Eliminate the coolant leak. Replace the damaged cylinder head gasket
The engine does not warm up to operating temperature for a long time, the thermal regime while driving is unstable:
- - Thermostat faulty (valve stuck in the open position) - Replace the thermostat
Constant drop in the coolant level in the expansion tank:
- - Radiator not tight - Replace the radiator
- - Expansion tank not tight - Replace the expansion tank
- - Water pump seal not tight - Replace the water pump
- - Coolant leaks through untight connections of unions and hoses - Replace the hose securing clips
- - Cylinder head securing bolts insufficiently tightened (during prolonged parking with a cold engine a coolant leak appears in the joint of the cylinder head with the cylinder block; besides, the appearance of coolant traces in the engine oil is possible) - Tighten the cylinder head bolts to the required torque
- - Heater radiator not tight - Replace the heater radiator
