1999 Nissan Quest Van overheats

My 1999 Nissan Quest was overheating so I took it to the mechanics and he said I need a new Radiator and Thermostat, so he replaced them both. 2 days later its still overheating so I took it back, he said you need a new water pump along with timing belt so he replaced them both then the next day its still overheating so I took it back and he said he had to replace the Thermostat Unit so he did, now 4 days later ! This morning I turn it on and there is a loud clicking sound but as soon as I drove away the sound is gone but I get on the freeway and it starts overheating again ! Does anyone know what it could be? Thank you