Short and simple version. replaced waterpump, thermostat, and flushed the radiator with acid cleaner. Still overheating and only place it loses water is overflow. what else could it be?

 

Instead of throwing everything at it why don't you just keep it simple and start with things like a radiator cap? I would also inspect the surface where the cap sits.

 

do yourself a favor and get a pressure tester for the cooling system and find the leak , when the radiator gets low it sucks from the overflow bottle. could have a head gasket leaking if no leaks are visible , could be alot of things but id start with a pressure test

 

What about the water temperature sensor? And what exactly does the sensor do and which parts do it effect? Or does it control the fans any because i think they are not working possibly all the time like they should. Thanks again for all the help.Literally only loses water out of the overflow when it overheats and i never let it actually go into the red. just short distances. And when in neutral coasting down a hill it cools extremely fast.

And will do pressure tester on payday tomorrow.

 

the sensor tells the pcm what temp the coolant is at and from there the pcm uses the information from the sensor to turn on the fans when needed as well as to calculate many things like fuel trims and spark advance etc..... the cooling fans dont run all the time , they run alot when the AC is on otherwise they will only run when the car gets to a certain temp , mostly in traffic or at stops when there is little or no airflow across the radiator. When you are coasting down a hill in nuetral you are applying no load to the engine and getting optimal airflow across the radiator so its expected to cool better and like i said the radiator pulls from the overflow bottle when it gets low (meaning there is some kind of leak somewhere). do you see any external coolant leakage? white smoke from exhaust? sweet smell of antifreeze?