How to Determine which Transmission Line is Return Line

Updated 05/25/2018 | Published 05/24/2018

Question:

on the radiator which is the return line top or bottom

asked by: Kenneth V

Expert Reply:

The best way to determine which line on a transmission cooler is the return line from the radiator is to use the following procedure:

1. Start engine while engine is cold
2. Place transmission shift lever in drive for no more than 10 seconds
3. Place in Park, stop engine, and remove keys
4. Identify the oil return line by feeling both oil lines. The coolest line is the oil return line.

On the aftermarket transmission cooler the ports are not input specific or output specific. It is not directional so you can choose either port for either function. You will want to choose the inlet or outlet port location by what will make your installation easiest.

I tried looking up your vehicle specifically but got conflicting info.

expert reply by: Jameson C