Characteristic | Meaning |
Maximum system pressure: | |
Petrol engine models: | |
Engine 1.4 l | 1.2 bar |
Diesel models | 1.2 bar |
Thermostat
Characteristic | Meaning |
Working temperature: | |
Starts to open at | 89°C |
Valve lift | 7.5mm |
General description
Sealed type cooling system (pressure above atmospheric), includes water pump (driven on 1.4 and 1.6 petrol engines by a toothed belt, and on 2.0 l engines and diesel models by an auxiliary belt), aluminum cross flow radiator, electric fan, thermostat, heater heat exchanger and associated hoses and switches.
The system functions as follows. Cold coolant from the base of the radiator passes through the lower hose to the water pump, which forces it through the engine and engine oil cooler passages (where available). After cooling the cylinders, combustion chambers and valve seats, the coolant enters the thermostat, which is initially closed. The coolant passes through the heater and returns through the cylinder block to the water pump.
While the engine is cold, coolant circulates only through the cylinder block, cylinder head and heater. When the liquid is heated to a certain temperature, the thermostat opens and the liquid passes through the upper hose to the radiator. Passing through the radiator, the liquid is cooled by the air flow generated during the movement of the car. When necessary, this flow is amplified by the operation of the fan.
On diesel models, coolant flows through the engine oil cooler or aftercooler and around the turbocharger (where available). On automatic transmission models, the coolant is also passed through the transmission fluid cooler.
As the engine warms up, the coolant expands and some of it moves into the expansion tank. After the system has cooled, the liquid returns from the tank to the radiator.
The electric fan, mounted behind the radiator, is started by a thermal switch that operates at a certain temperature of the coolant.
Precautions
Do not remove the expansion tank filler cap or separate parts of the cooling system until the engine has cooled down as hot vapor and liquid may be released. If for any reason the cap does come off, carefully depressurize the system. To do this, cover the lid with a thick cloth folded several times and slowly unscrew it until you hear a hissing sound. When the hissing stops (pressure released), slowly unscrew the cover and remove it; if the hissing continues, stop and wait until it subsides. Keep your face away from the filler neck and protect your hands with gloves.
If antifreeze comes into contact with your skin or painted surfaces of your vehicle, immediately wash off the spilled drops with plenty of water. Never leave antifreeze in an open container or spilled on the garage floor - the deadly poisonous liquid can attract children and pets with a pleasant smell.
When working on models equipped with air conditioning, be guided by the Precautions listed in Section Removal and installation of heater components (Scenic models).