- check the hose connections on the radiator, pump, thermostat housing and heater;
- rubber hoses must not lose elasticity, be brittle or cracked. Old hoses often begin to leak or break at maximum system pressure;
- if the radiator is leaking, then one of the thin tubes under the plates is probably damaged or there is a crack in the plastic tanks;
- the thermostat must be in good working order;
- check the serviceability of the viscous coupling of the fan drive;
- The pump may be leaking if the coolant pump seal is damaged. In this case, the coolant flows from under the pump through the hole behind the pulley. The pump should be replaced;
- rubber sealing gaskets of the expansion tank plug must not lose elasticity or have cracks;
- if the system hoses are compressed after the engine cools down, the valve in the expansion tank cap is damaged.