General description
The engine cooling system maintains the engine temperature 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 the radiator and recirculation subsystem, cooling fans, thermostat and housing, water pump and water pump drive belt. The timing belt drives the water pump.
For the cooling system to function, all components must work properly. The water pump draws coolant from the radiator. Coolant circulates through water jackets in the cylinder block, intake manifold and cylinder head. When the coolant temperature reaches the operating temperature of the thermostat, the thermostat opens. The coolant then returns to the radiator where it cools. The system directs some of the coolant through the hoses to the heater heat exchanger. This ensures heating and defrosting. The expansion tank is connected to a radiator to receive coolant displaced by high temperatures.
The expansion tank ensures the correct coolant level.
The cooling system of this engine does not have a radiator cap or filler pipe. Coolant is added to the system through the expansion tank.
Radiator
This car has an aluminum plate-pipe radiator with lightweight design. Plastic tanks are installed on the right and left side of the radiator heat exchanger.
On vehicles with an automatic transaxle, the transmission fluid cooling lines run through the left radiator tank. The drain plug is on this radiator. To empty the cooling system, open the drain plug.
Expansion tank
The expansion tank is a plastic container similar to the windshield washer reservoir.
The expansion tank is connected to the radiator by a hose, and the engine cooling system is connected to another hose. When the vehicle 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. The air in the radiator and engine is forced out into the expansion tank.
When the engine is stopped, the coolant cools and contracts. The displaced engine coolant is returned back to the radiator and engine. This maintains the correct level of coolant 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 impeller pump. 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 (blades). As the impeller rotates, the coolant between the vanes is pushed outward by centrifugal force. The impeller shaft is supported by sealed bearings. Sealed bearings do not require lubrication. Grease cannot leak out and dirt and water cannot enter until the seal is damaged or worn.
The water pump is mounted on the front cover of the engine and is driven from the crankshaft pulley by a multi-ribbed drive belt that rotates the pump pulley bolted to the water pump flange. Coolant enters the engine through the coolant inlet pipe and thermostat on the rear of the engine, passes through the engine to the water pump on the engine front cover, and exits through the coolant outlet housing at the front of the intake manifold.
Thermostat
The coolant inlet uses a steam valve type thermostat, opened by the melting of a wax ball encapsulated in a special capsule, to control the flow of coolant, allowing the engine to warm up quickly and regulate the coolant temperature. A wax ball or energy element in a thermostat expands when heated and contracts when cooled. The wax ball is connected by means of a piston to the valve, and when the ball is heated, 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. Thus, the valve remains closed at low coolant temperatures, 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 and keep the engine temperature within the specified range.
The thermostat also serves as a limitation in the cooling system, even after it has been opened. This restriction creates a pressure differential that prevents cavitation in the water pump and forces the coolant to circulate around the cylinder block.
The thermostat starts to open at 82°C (179,6°F) and fully opens at 95°C (203°F).
Cooling fan
Attention! To prevent injury, keep hands, tools, and clothing away from the cooling fan. The fan is electrical and can turn on whether the engine is running or not.
Attention! If the 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 - a main fan and an auxiliary fan. Electric fans of the cooling system increase the air flow through the radiator fins and through the condenser on vehicles equipped with air conditioning. This allows faster cooling at idle or low speeds.
Vehicles with and without air conditioning have two fans in the shroud. Main fan size - 340 mm (13.4 inches) in diameter with five blades, and the auxiliary - 320 mm (12.6 inches) in diameter with seven blades. They contribute to the passage of air through the radiator and condenser. Two fan motors attached to the center of each fan on the shroud assembly drive both fans.
When the air conditioner is off or for a model without air conditioning
- The cooling fans are driven by the ECM through the series/parallel cooling fan relay.
- The ECM turns on the cooling fans at low speeds if the coolant temperature reaches 100°C (212°F), and at high speeds if the coolant temperature reaches 110°C (230°F).
- ECM switches cooling fans from high to low speed at 108°C (226,4°F) and turns them off at 98°C (208,4°F).
A/C on
- The ECM turns the fans on slowly when the A/C system is on. The ECM switches to a fast fan speed when the coolant temperature reaches 110°C (230°F) or when the high pressure side of the air conditioner reaches 1760 kPa (255 psi inch).
- Cooling fans return to low speed when coolant temperature reaches 100°C (212°F) and when the high pressure side of the air conditioner reaches 1347 kPa (195 psi inch).