Trans cooler being added

[uniquebrett]

I have a 97 gmc K1500 z71 with the 4L60E....Which of the steel trans fluid lines on the pass. side of the trans. is the out going and which is the incoming ? I would expect the top line is outgoing (hot) and bottom is incoming ( cool) is this correct?

[unsolved]

Just remember gravity and you'll be fine. The top would be the output from the pump and the bottom would be the return.

[ridgekid]

At the radiator, the bottom is in and the top is return. If your adding a tranny cooler come off the top line, go to your add on cooler and them back to the tranny. Thats the way GM does it. (Just looked at mine)

[C & A s Dad]

Since yours is a 97 I would want to double check.

 

Once you remove the line from the radiator, insert the fitting into the radiator and slip your hose over the fitting and place it into a container. Have someone crank the truck for just about 3 seconds and you should have fluid coming out of the line.

 

You can also hold both lines in your hand while they are completely cold, have someone start the truck and put it in drive with the brakes on, the line coming to the radiator will begin getting warm first letting you know the other line is the rtn line and the one you want to tap into to go to your aux cooler.