The hoses must be put on the connecting pipes to the end. Check the reliability of the fastening of the hoses with clamps, if necessary, replace the clamps.
Check the expansion tank cap seal for damage.
Attention: Too low coolant level in the cooling system may be the result of a poorly or incorrectly screwed cap.
If the coolant level drops frequently and leaks cannot be located, a system check should be performed with the engine warm. If, when the engine is warm, coolant flows from the hole in the lower part of the pump, then, as a rule, there is a defect in the pump shaft seal. In this case, replace the coolant pump.
Obvious loss of coolant and/or presence of oil in the coolant with white exhaust gases from a warm engine indicates a defective cylinder head gasket.
Attention: Finding a leak is sometimes very difficult. In this case, a pressure test of the cooling system in a workshop is recommended (special device required). At the same time, you can check the overpressure valve in the cap of the expansion tank.