Installing auto transmission cooler.

[projectionist44]

I'm going to be installing a transmission cooler in my 2011 chevy silverado 1500 reg cab W/T. Does anybody know which one is the return line. My truck is equipped with the 4.3 v6 and the transmission cooling lines enter the radiator on the passenger side top and bottom. Derale performance says the transmission cooler should be connected to the return line for best results. The directions say find the cooler of the two lines and that one is the return line. I started the truck up and let it run for a while and they both feel like the same temp to me. I watched a few install vids of different engine configurations and years then my truck, some are located on the top and some on the bottom. Don't want to screw it up. 

[Mikebtte]

On my 2008 the top transmission line coming from the top of the radiator is the return line. May very on an 11, but I would think not.

The top line runs to the cooler and than returns to the transmission. Bottom line would be left alone.

[Grumpy Bear]

Top line is the return to the transmission. Lower line then from the transmission. 

[Jsdirt]

Every GM I've ever seen in the past, including my '07, the feed went into the top, and the return came out the bottom. Looks like they did a 180° on me again ... or I've just forgotten which is what.

 

My '93 Volvo 940 is the only vehicle I've ever seen with the return coming out the top.

 

What I would do in this case, is disconnect a line, attach a hose to it and feed it into a bucket, and get a stiff piece of cardboard or metal to direct any blast that may or may not come from the radiator, and have someone crank the truck for 1 second in clear-flood mode (pedal to floor) while you watch - it's either going to blast out of the radiator, or the line. 50/50 gamble. Won't hurt a thing. If the truck starts make sure you've drilled into their head to IMMEDIATELY turn the key off. 

 

If you're not comfortable doing clear flood mode, yank the ignition fuses.

[Grumpy Bear]

35 minutes ago, Jsdirt said:

Every GM I've ever seen in the past, including my '07, the feed went into the top, and the return came out the bottom. Looks like they did a 180° on me again ... or I've just forgotten which is what.

 

My '93 Volvo 940 is the only vehicle I've ever seen with the return coming out the top.

 

What I would do in this case, is disconnect a line, attach a hose to it and feed it into a bucket, and get a stiff piece of cardboard or metal to direct any blast that may or may not come from the radiator, and have someone crank the truck for 1 second in clear-flood mode (pedal to floor) while you watch - it's either going to blast out of the radiator, or the line. 50/50 gamble. Won't hurt a thing. If the truck starts make sure you've drilled into their head to IMMEDIATELY turn the key off. 

 

If you're not comfortable doing clear flood mode, yank the ignition fuses.

Wont work in this case JS unless the trans temp is higher than the stat setting. People get faked out all the time by this. When the valve is closed the fluid runs via the bypass in the stat to the return line making it look like the supply. I pulled my stat and I have the LV3 4.3 and 6L80E. Top hose is the return. 

[Doug_Scott]

Why would they put a thermostat in transmission?  Automatic transmissions get warmed up pretty quickly without a thermostat, and if anything they needed more cooling. 

The only reason for putting an aux cooler in the return line is that the cooler in the radiator can only bring temp down to engine temp. It would seem if they are bypassing until its warmed up it won't matter which line you choose. 

[Jsdirt]

I wasn't aware of a t-stat either ... but wouldn't shock me that GM decided to throw yet another unnecessary, failure prone part into the mix of over-engineered, rolling computerized Tupperware ...