Trans lines to radiator (top/bottom)?

[jalapeño]

C4 fluid lines: I know the rear is return & front is out, and Im fairly certain the proper sequence is radiator first then aux. cooler. Question is: When hooking up the lines to the radiator, does it make a difference which line (return or out) goes to the top or bottom fitting? Is one a better in/outlet top or bottom?

 

[73azbronco]

I'd say top is from c4, this lets the line run another foot or so before it hits the rad, with a shorter return to c4. Other than that, I don't know.

 

[DirtDonk]

I've always plumbed an input into a lower port if it was available. That way it seems that any air would be forced out the top and not create a pocket.
Probably not an issue with a trans, but that's how I think of any type of fluid line.

And there is a school of thought too, that says to run it through the auxiliary first, to give it an initial cooling, then on into the radiator. That way, if it's hot, you're not putting any more heat into the radiator than you have to (although the heated air from the aux cooler is still going through the rad), and if it's cool out, the engine heat will normalize the heat in the trans.

Nothing scientific in what I said, but we've had discussions here and on the full-size boards over the years about the "which one first" debate.

Paul

 

[Broncobowsher]

I like to do bottom up as well. Better for working the air bubbles out. Also consider how the bubbles will work out of the oil to air cooler as well. I have heard that people getting better trans cooling by turning the cooler 90° so it wasn't trapping air bubbles.

 

[Rustytruck]

since you live in snow and Ice country if you brave the cold winters in your Bronco you will want to run through the extra cooler first then through the radiator. out west we want to run the other way around as not to add heat to an already marginal cooling system. I myself only run a cooler and do not use the in radiator cooler. If I lived where you do I would rig bypass valves so I can run through the cooler only during the summer and then valve over to the radiator during the winter bypassing the added cooler. Automatics like to run cold but not Ice cold.