The hoses must be pushed onto the connecting fittings all the way.
Check the reliability of the hose clamps. If necessary, install new clamps tightened with screws instead of the previously used clamp clamps.
Check the expansion tank cap seal for damage.
If the coolant level drops frequently and it is not possible to determine the leaks, then it is necessary to check the cooling system with the engine warmed up. To do this, warm up the engine and then run it at idle until the fan turns on. Check whether coolant is coming out in the area of the cooling system pump.
Obvious loss of coolant and/or oil in the coolant, as well as white exhaust gases when the engine is warm, indicate a defective cylinder head gasket.
Note: Sometimes it is very difficult to locate the leak. In this case, it is recommended to test the cooling system under pressure, see chapter "Checking the cooling system for leaks". At the same time, you can also check the excess pressure valve in the expansion tank cap.