Finding the Transmission Cooler Return Lin on a 2004 Chevy Express

Question:

There are two existing transmission lines connecting the transmission to the transmission cooler integrated into the factory radiator. I would like to know which line carries the flow back into the transmission and which carries the flow out of the transmission to the radiator. I though it would be best at tap into the return line since that would provide better cooling. I plan to mount the aux trans cooler in front of the radiator and a/c condenser. Thank you.

asked by: Dan L

Expert Reply:

The easiest way to determine the return line on your 2004 Chevy Express transmission is to start the truck, shift into drive but do not go anywhere. After about 15 seconds or so put the truck back in park and apply the emergency brake. Turn off the truck. Out of the 2 hoses attached to the transmission, one should be warmer than the other. The one that is cooler is the return line. It may sound a little too easy but it works.

Connecting the supplemental cooler, # D13102, to the return line is the preferred method of installation. I have included some links that you may find helpful for this project.

expert reply by: Michael H