Car is only overheating when idling , not when on highway

on 2002 Land Rover Discovery

already changed: water pump twice, therm,. hoses. fan

Asked by for the 2002 Land Rover Discovery
You could have a failed cooling fan viscous hub or a thermostat that is not fully opening. Feel that the radiator has no cold spots when the engine is warmed up (would be a sign of a restricted radiator). Possible check for the presence of Carbon Monoxide in the cooling system, CO would be only present if the head gasket was blown.