How to Which Transmission Cooler Line is the Return Line on a 2001 Chevy Silverado

Question:

I bought the D13504 cooler for my 2001 Silverado. I would like to know which transmission line I should run into the D13504 cooler. The top line or the bottom line from the radiator?

asked by: Dennis F

Expert Reply:

You will want to run the return line from your factory cooler to the Derale Transmission Cooler # D13504. Here is an easy way to figure if the top or the bottom line is the return line.

The method for determining which line is the return line is to:
1. Start engine while engine is cold
2. Put your transmission into Drive for no more than 10 seconds
3. Stop engine, remove keys
4. Identify oil return line by feeling both lines, the cooler of the two is the return line and the line you should install your # D13504 in that line.

I have included a link to an FAQ on transmission coolers below, as well as a video of a transmission cooler being installed on a vehicle

expert reply by: Jameson C