1. Open the hood and inspect the underhood space. When inspecting the engine, pay attention to the presence of coolant in the expansion tank, the integrity of the rubber hoses, radiator...
2. ...and thermostat.
Note: A burst hose can be temporarily repaired using adhesive tape.
Reinforced adhesive tape is especially well suited for this purpose (for example, silver color), which can be purchased at auto stores.
If coolant leaks from under the thermostat housing, tighten its mounting bolts. If tightening the bolts does not eliminate the leak, it must be removed, the mating surfaces must be cleaned and installed using Loctite 518 or similar sealant.
3. Inspect the hose connections to the cover and thermostat housing...
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4. ...and also with the heater radiator pipes. If coolant leaks, replace the hose clamps.
Note. There are two valves installed in the expansion tank cap: inlet and outlet. The outlet valve plays a major role in ensuring the optimal engine temperature. It maintains an excess pressure of approximately 0.14 MPa in the system (1.4 kgf/cm²), providing an increase in the temperature at which the coolant begins to boil and preventing intensive vaporization. Unfortunately, when the valve gets stuck in the closed position due to overheating, a significant excess of excess pressure occurs, which can lead to a rupture of the expansion tank or a tear in one of the hoses. In turn, jamming 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, and check the valve for sticking. If in doubt, replace the cap. 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.