i need some help , does anyone know on my a pontiac sunfire gt 2.3L , what is the plastic tubing connected to the head that the top radiator hose goes to , theres a sensor hooked up to it , the heater core hose goes to the side of it , and the radiator spill over metal line goes it it ? It looks like the thermostat housing but is plastic and thermostat isnt on there? I need some help yall so let me know asap