The top hose.
There are 2 lines. The return line is the line that is the the coolest after running the car. Usually the top line.
BOTTOM
The lower radiator hose supplies the water pump. The upper radiator hose supplies the radiator.
Connected to the bottom of the radiator you will see 2 lines. One is the inlet and one is the outlet. The cooler line is the return (outlet) line.
The top line is always the return line, The cooler has to fill from the bottom or the fluid would get airated.
unplug line at bottom of overflow or bottom of radiator
Only if you drive the vehicle. It can't return the water line without the receipt. Get literate!
Remove the top water line from the radiator to the water pump. The thermostat is found there.
Remove the top water line from the radiator to the water pump. The thermostat is found there.
touch it ,the cooler one is usually return
that is the transmission return cooler line
Lower radiator hoses in water cooled engines are return lines. The upper radiator hoses are feed lines of hot engine water to the radiator. The reason that lower hoses are cooler is that the radiator has allowed much of the water's heat to dissipate into the air. Thus, a lower radiator hose contains cooler water than other radiator and heater hose lines.