Contents: General description ↧ Radiator ↧ Expansion tank ↧ Water pump ↧ Thermostat ↧ Cooling system fan ↧ With the air conditioner turned off… ↧ The air conditioner is on ↧
General description
The engine cooling system ensures that the engine temperature is maintained at an efficient level in all engine operating modes.
When the engine is cold, the cooling system cools the engine slowly or not at all. This slow cooling allows the engine to warm up quickly.
The cooling system includes a radiator and recirculation subsystem, cooling fans, thermostat and housing, water pump and water pump drive belt. The timing belt rotates the water pump.
For the cooling system to function, all components must work properly. The water pump sucks coolant from the radiator. The coolant circulates through water jackets in the engine block, intake manifold, and cylinder head. When the coolant temperature reaches the thermostat's operating temperature, the thermostat opens. The coolant then returns to the radiator where it is cooled. The system directs some of the coolant through hoses to the heater core. This provides heating and defrosting. The expansion tank is connected to the radiator to receive the coolant displaced by the high temperature.
The expansion tank ensures the correct coolant level.
The cooling system of this engine does not have a radiator cap or filler neck. Coolant is added to the system through an expansion tank.
Radiator
This car has an aluminum radiator with a light-weight plate pipe. Plastic tanks are installed on the right and left sides of the radiator heat exchanger.
On vehicles with an automatic transmission with a final drive assembly, the transmission fluid cooling lines pass through the left radiator tank. The drain plug is located on this radiator. To drain the cooling system, open the drain plug.
Expansion tank
The expansion tank is a plastic container similar to a windshield washer reservoir.
The expansion tank is connected to the radiator by a hose, and the engine cooling system by another hose. When the car is running, the engine coolant heats up and expands. Some of the engine coolant displaced by this expansion flows from the radiator and engine into the expansion tank. Air in the radiator and engine is forced into the expansion tank.
After the engine is stopped, the coolant cools and compresses. The displaced engine coolant flows back into the radiator and engine. This maintains the required coolant level in the radiator and increases cooling efficiency.
Set the coolant level between the MIN and MAX marks on the expansion tank when the system is cold.
Water pump
The water pump is a centrifugal pump with an impeller. The pump consists of a casing and an impeller. The impeller is a flat plate mounted on the pump shaft with a series of flat or curved blades (vanes). When the impeller rotates, the coolant between the blades is forced out by centrifugal force. The impeller shaft is supported by sealed bearings. Sealed bearings do not require lubrication. Lubricant cannot escape, and dirt and water cannot get in unless the seal is damaged or worn out.
The water pump is mounted on the front engine cover and is driven from the crankshaft pulley by a multi-groove drive belt that rotates the pump pulley, which is bolted to the water pump flange. Coolant enters the engine through the coolant inlet pipe and thermostat at the rear of the engine, passes through the engine to the water pump on the front engine cover, and exits through the coolant outlet sump located at the front of the intake manifold.
Thermostat
The coolant inlet uses a steam valve type thermostat that opens due to the melting of a wax ball enclosed in a special capsule to control the flow of coolant, ensuring rapid engine warm-up and coolant temperature regulation. The wax ball, or energy element in the thermostat, expands when heated and contracts when cooled. The wax ball is connected to the valve by means of a piston, and when the ball heats up, pressure is applied to the metal valve, which is forced to open.
As the ball cools, its compression allows the spring to close the valve. This keeps the valve closed when the coolant temperature is low, preventing coolant from circulating through the radiator, but allowing coolant to circulate through the engine to warm it up quickly and evenly. As the engine warms up, the ball expands and the thermostat opens, allowing coolant to flow through the radiator, where heat is transferred through the radiator walls to the surrounding air.
This opening and closing of the thermostat valve allows enough coolant to flow into the radiator to maintain the engine temperature within the specified range.
The thermostat also acts as a restriction in the cooling system, even after it has opened. This restriction creates a pressure differential that prevents cavitation in the water pump and forces coolant to circulate through the cylinder block.
The thermostat begins to open at 82°C (179.6°F) and is fully open at 95°C (203°F).
Cooling system fan
Caution! To prevent injury, keep hands, tools, and clothing away from the cooling fan. The fan is electric and may turn on whether the engine is running or not.
Warning! If a fan blade is bent or damaged in any way, do not attempt to repair or reuse the damaged part. A bent or damaged fan must be replaced with a new one. Failure to do so may result in injury.
The cooling fans are installed behind the radiator in the engine compartment. The cooling system of this vehicle has two cooling fans - the main and auxiliary. Electric cooling fans increase the air flow through the radiator fins and through the condenser on vehicles equipped with air conditioning. This allows for faster cooling at idle or low speeds.
Cars with and without air conditioning have two fans in the casing. The size of the main fan is 340 mm (13.4 inches) in diameter with five blades, and the auxiliary one is 320 mm (12.6 inches) in diameter with seven blades. They help draw air through the radiator and condenser. Two fan motors, attached to the center of each fan on the assembled shroud, drive both fans.
With the air conditioner turned off or for a model without air conditioning
- The cooling fans are driven by the ECM via the series/parallel cooling fan relay.
- The ECM turns on the cooling fans at low speed when the coolant temperature reaches 100°C (212°F) and at high speed when the coolant temperature reaches 110°C (230°F).
- The ECM switches the cooling fans from high to low speed at 108°C (226.4°F) and turns them off at 98°C (208.4°F).
The air conditioner is on
- The ECM turns on the slow speed of the fans when the A/C system is on. The ECM switches to high speed of the fan when the coolant temperature reaches 110°C (230°F) or when the high side of the A/C pressure reaches 1760 kPa (255 psi).
- The cooling fans return to low speed when the coolant temperature reaches 100°C (212°F) and when the high side of the air conditioner reaches 1347 kPa (195 psi).