In the instrument cluster of any car there is a coolant temperature indicator 1. In addition, in the instrument cluster lamp block of your car there is a warning lamp 2 for engine overheating. If the engine overheats, the scale of the indicator is completely shaded (under normal temperature conditions, only the four lower divisions of the scale are shaded) and the signal lamp lights up.
Checking the cooling system
At the first signs of overheating, if the temperature gauge scale is completely shaded, but no clouds of steam are escaping from under the hood, turn on the maximum cabin heating mode, see. "Heating (conditioning) and interior ventilation". This is necessary in order to reduce the temperature of the coolant in the engine cooling system.
Turn on the hazard warning lights, depress the clutch pedal, then, using the car's momentum, try to carefully move to the edge of the roadway and stop as far to the right as possible at the curb, and if possible, outside the roadway. Let the engine run for a couple of minutes at normal crankshaft speed at idle, with the heater on full power.
Warning! Do not stop the engine immediately! The only condition is to maintain the tightness of the cooling system. If a hose bursts or comes off, or another leak occurs, in addition to the liquid being released from under the expansion tank cap, the engine will have to be stopped immediately.
After an overheated engine stops, local overheating of the coolant begins in the places where it contacts the most heat-stressed engine parts and vapor locks form. This phenomenon is called "thermal shock".
1. Stop the engine.
2. Open the hood and inspect the underhood space. Determine where the steam is escaping from. When inspecting the engine, pay attention to the presence of coolant in the expansion tank, the integrity of the rubber hoses, radiator, thermostat.
Warning! Never open the expansion tank cap immediately. The liquid in the cooling system is under pressure, when you open the cap the pressure will drop sharply, the liquid will boil and its splashes can scald you. If you want to open the expansion tank cap on a hot engine, first put a thick, dense rag on top and only then carefully turn the cap.
3. Look under the dashboard on the front passenger side and determine if there is a leak or traces of coolant flowing from the heater core.
If a coolant leak is detected, the burst hose can be temporarily repaired with tape.
Note: Reinforced concrete is particularly well suited for this purpose (for example, silver color) adhesive tape, which can be purchased at auto stores.
A leak in a radiator, thermostat or heater is quite difficult to fix on the spot, so in such a situation it is necessary to add water to the cooling system and carefully monitor the temperature gauge while driving, periodically restoring the level in the cooling system.
Warning! Long-term use of water instead of antifreeze leads to scale formation in the engine cooling system, deterioration of its cooling and, as a result, to a reduction in service life. Never add cold water to an overheated engine. The engine must cool down with the hood open for at least 30 minutes.
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4. The engine may overheat if the thermostat, which regulates the flow of fluid in the cooling system through or past the radiator, fails (to speed up the warming up of a cold engine). To check the thermostat, you need to check the temperature of the lower hose connecting the radiator to the engine by touch on a warmed-up engine. If the lower radiator hose is cold, the thermostat is faulty, there is no circulation through the radiator.
5. Very often the cause of overheating of an engine, the cooling system of which is equipped with an electric fan, is the failure of the fan.
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6. Start the engine, monitor the temperature and pay attention to whether the cooling system fan turns on when the engine overheats. If it does not turn on, the reasons may be a faulty additional resistor, a blown fuse, a faulty start relay, oxidized contacts in the wiring harness block or a burnt-out electric motor.
7. Replace fuse 2 in the fuse and relay box installed in the engine compartment. If the fan still does not work after replacing the fuse, replace relays 1 and 3 in the same box. If the fan still does not work after replacing the fuse and relay, check the electric motor by taking two additional wires and supplying power to it directly from the battery. The wires must be securely fastened and insulated.
Attention! Do not allow the wires to short-circuit each other! Pay attention to the polarity of the connection: the electric motor must rotate so that the fan forces air through the radiator onto the engine, and the directions of the generated flow and the incoming (path) air flow coincide.
If the electric motor starts to work, the wiring or the cooling system fan relay is faulty; if not, the wiring or the electric motor itself is also faulty. The relay and the electric motor cannot be repaired, replace them as a whole (see section "Electrical equipment").
Note. There are two valves installed in the expansion tank cap – an inlet and an outlet valve. The outlet valve plays a major role in ensuring the optimal temperature regime of the engine. It maintains excess pressure in the system of at least 0.13–0.15 MPa (1.3–1.5 kgf/cm²), ensuring an increase in the boiling point of the coolant and preventing intensive vaporization. Unfortunately, when the valve jams in the closed position due to overheating, a significant excess of excess pressure occurs – more than 0.15 MPa (1.5 kgf/cm²), which can lead to a rupture of the expansion tank or a tear in one of the hoses. In turn, jamming of the valve in the open position leads to premature boiling of the coolant.
Therefore, once a year, wash the expansion tank cap with running water. If in doubt, replace the cap. Obviously, if you remove the expansion tank cap on an overheated engine and this action coincides with a "thermal shock", then boiling of the liquid and the formation of air locks in the cooling system are guaranteed. Once a year, blow out the radiator cells with a stream of compressed air (for example, from a compressor), directing the stream first towards the oncoming air flow, and then in its direction to remove dirt, stuck insects and road debris from the radiator surface. This can partially restore the radiator's efficiency.
(Original publication on the website: www.Renaultbook.ru)