Which Line Is Transmission Fluid Return Line on 2009 Chevrolet Tahoe

Question:

Which is the return line to the transmission? Top of the radiator or bottom. I connected my cooler to the bottom. Is that right?

asked by: Reid L

Expert Reply:

Typically the return line of the transmission is the one at the bottom of the cooler. You can do a small test to determine which line is the return line.

First, start engine while engine is cold.
Put the transmission in drive for no more than 10 seconds
Stop engine
Feel the both of the lines, and whichever one is cooler is the return line that is taking the fluid back to the transmission.

To install the cooler you selected, Derale Transmission Cooler, part # D13611, you will also need the Derale Snap-In Radiator Adapter Fitting, part # D13035.

I have linked an FAQ on transmission coolers.