Which line is the trans fluid return line?

I searched but couldn't find the answer. I'm putting a tranny cooler in my Jeep next week and I want to use the return line to feed my new cooler. Whicn line is that? I assume it is the lower line but I wan to make sure before I start cutting stuff up.

Heres how I did it....
From a cold start ;
1) Run the engine and shift thru gears for a short time. (Maybe around the block)
2) Grab the lines which ever line feels higher in temp. will be your return line.

Nick

The easier way is to read this.....



it's the lower line

Its the line that runs to the back end of the tranny. The front end is the pump.

as above, it's the line that goes to the REAR of the transmission

cooler lines around the radiator and factory cooler (if you have one) are a real mess, ignore all that stuff and just pay attention to what is coming out and going back into the tranny

Didn't want to post the same question again..

On my XJ the rear line goes to the top of the radiator and the front goes to the bottom of the radiator...

I understood that the line connected to the front of the transmission is suppose to go to the top of the radiator...

Hope someone could clear this up..

I've traces the lines many, many times and somthing seems wrong...

Thanks...

I think yours is right. The bottom fitting is the inlet. That way the cooler is self-bleeding. Air would float to the top and return to the trans sump. Otherwise, the cooler could retain a large amount of air, allowing less surface contact with the oil.

E C Yarter

hanaxj87 said:

Heres how I did it....
From a cold start ;
1) Run the engine and shift thru gears for a short time. (Maybe around the block)
2) Grab the lines which ever line feels higher in temp. will be your return line.

Nick

Click to expand...

If this is a transmission cooler, shouldn't the return line be cooler than the cooler inlet line.

Ok, I'll add to the confusion, (as an ex-supplier engineer of automotive cooling systems to Chrysler and others). The oil flow of the in-tank tranny cooler is supposed to be opposite to the flow of coolant in the radiator. In the radiator, the coolant flows from top to bottom, so the tranny oil SHOULD flow in from the bottom to the top. I can't say that this is really how they did it, but this is the recommendation of the cooler manufacturers.

So the only known fact is that the line from the front of the trans is the one from the pump which should be the inlet line to the cooler. And the trans return line goes in towards the rear.

Got it...

I just left it with the same route. Pump side on the bottom, return side on top.

Eliminated the radiator all together. It's connected straight to the cooler, stand-alone.

Just weird everyone posting that the return line should be on the bottom of the radiator.. Even the FSM indicates the same...

When flushing the system, I disconnected the top hose, replaced it with a short piece. Then to an empty gallon jug. Just repeated until the old was out.