Don, I understand that completely. The rad tank helps warm the trans fluids, which helps the trans heat up faster in colder climates. I am not worried about that in the least bit. This rig is only used in spring/summer/fall. I have an inline filter installed, and it is directional. Easy to figure out the flow direction.
This is just for discussions sake:
I'm going for the opposite, because of towing. I want the engine coolant in the rad, to reduce those temps. My ultimate goal is to have the trans and engine run at the same temps. Somewhere around 195* would be perfect. Doable? That is the question, and the reason for trying this.
When towing, the trans temps are hotter than the engine temps, with the rad bypassed as is. Engine at 195* & Trans hitting 200-210* in 3rd gear, OD off. OD on is when it climbs to 230* at speed. Ack...
So my brain says to me that if the 210* trans fluids hits the 195* rad tank, it's going to either heat the coolant to 210*, or the engine coolant will reduce it to 195*.
I don't want to heat the coolant higher with the hotter trans fluids. If the trans fluids gets cooled by the aux cooler/fan first, then enters the rad tank to match the engine temps, before returning to the trans, that would be great.... "IF" it works that way. According to Ford's routing, this is the way they say it should be. Is this the reasoning as to why? I Dunno.
If the rad can drop the trans fluid to match the coolant temps, w/o heating it up, then the aux cooler drop's it a few more degrees, then great.
I'm just thinking this out before I plumb it, in hopes not to have to do it twice, meaning time and new hose.
I can't use the longer F-250/350 coolers on this rig. The front skid is in the way for that. I have the aux cooler in front of the condenser, with a pusher fan on it. If I could fit a thicker cooler I would step up to a better one, but can't. Only have 3/4" thickness room, and the bigger plate coolers I have found are 1.25" thick, or more.