Tranny cooler lines

[Ranger4x4newb]

I'm trying to add a second cooler to my tranny and I've got 2 questions if anyone can help.
First off its a 98 4x4 auto with a 4.0 5r55e.
I'm trying to figure out what size the cooler lines are and which one is the return line going from the stock cooler back into the tranny. Thanks!

 

[willy]

3/8

 

[ghunt81]

The line coming out of the bottom of the radiator is the return line according to what I've read.

 

[Ranger4x4newb]

3/8

The line coming out of the bottom of the radiator is the return line according to what I've read.

Thank you both.
The only problem however, my tranny cooler isn't mounted internally to the radiator, its an external unit and its not aftermarket either.

 

[ghunt81]

I'll have to try to remember to look at mine and see if I can see which line port on the transmission is the return line, I don't know off the top of my head.

 

[Mickey Bitsko]

You want your top line going into the radiator to be in line with your auxiliary cooler, that line is coming from the trans and in need of cooling. The bottom radiator tans line has been cooled and going back to the trans.

 

[ghunt81]

He already said he doesn't have the cooler in the radiator.

Also I forgot to look at mine last night, sorry. I was looking right at it while working on something else and thinking about that, then it slipped my mind.

 

[adsm08]

There has to be a cooler in the rad. Ford has NEVER used just an oil to air cooler on an auto trans, they aren't efficient enough.

If you have a trans cooler up front that isn't in the rad that is an auxiliary cooler, and the primary should be part of the rad. If there isn't one in the rad at all someone installed a manual trans radiator on your truck.

 

[Ranger4x4newb]

There has to be a cooler in the rad. Ford has NEVER used just an oil to air cooler on an auto trans, they aren't efficient enough.

If you have a trans cooler up front that isn't in the rad that is an auxiliary cooler, and the primary should be part of the rad. If there isn't one in the rad at all someone installed a manual trans radiator on your truck.

I'll try to get a picture of it and post it either tonight or tomorrow

 

[ghunt81]

If there isn't one in the rad at all someone installed a manual trans radiator on your truck.

Which is very likely...lines rusted and/or broke, someone that didn't know better put in the wrong radiator and just plumbed around it. Wouldn't surprise me in the slightest.