How To Find the Transmission Cooler Return Line From Radiator on a 1993 Chevy C2500

Question:

I just installed a BandM 70268 transmission cooler in my 1993 Chevy C2500. I have a Haynes and Chilton repair manuals, but neither shows which line is the transmission return line from the radiator.The only info i found was in the BandM documentation which suggests the upper line on the radiator is the return. Is this accurate? Also, the BandM cooler does not indicate an input or output, and no info in the documentation. Does it matter which port to connect the return from the radiator? Thank you in advance for any advice.

asked by: Michael R

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.

expert reply by: Jeff D