Examine coolant hoses for porous spots by compressing and bending, hardened hoses should be replaced.
The hoses must not sit too short on the connection fittings.
Check hose clamps for tightness.
Check the radiator filler cap gasket for damage.
Warm up the engine and check for coolant leaks around the coolant pump.
If on a hot engine coolant flows out of the hole under the pump, then, as a rule, the o-ring is defective (stuffing box) pump shaft. In this case, replace the coolant pump.
Sometimes it can be difficult to locate a leak. In this case, a pressure test in a workshop is recommended (special device required). It is also possible to check the overpressure valve of the radiator cap.