Transmission Cooler Lines Flow Direction
 

Hi there, I've searched and can't seem to find a direct post about this. I'm gearing up to put an external tranny cooler on and am trying to determine which existing cooler line is the return line back to the transmission from the factory cooler. Can someone tell me if I have this diagram correct? Thx.

Not 100% sure, but I believe that you have those reversed; the driver's side is the "out" (from trans to radiator) and the passenger side is "in" (back to the trans). Hopefully someone can verify that.

Table♦1: Direction of Fluid Flow in Oil Cooler Pipes at TransmissionTransmission
Oil Cooler Feed (Exiting Transmission)
Oil Cooler Return (Entering Transmission)
200-4R
top connector
bottom connector
3L30 (180)
front connector
rear connector
3L80 (400)
bottom connector
top connector
4L30-E
front connector
rear connector
4L60 (700-R4)
bottom connector
top connector
4L60-E
bottom connector (may require J-35944-200)
top connector (may require J-35944-200)
4L80-E
front connector (may require J-35944-200)
rear connector (may require J-35944-200)
3T40
bottom connector
top connector
4T40-E
top connector (requires J-35944-440)
bottom connector (requires J-35944-440)
4T60 (440-T4/F7)
vertical (top) connector
horizontal (bottom) connector
4T60-E
vertical (top) connector
horizontal (bottom) connector
4T65-E
vertical (top) connector
horizontal (bottom) connector
4T80-E
front connector (case cover)
rear connector (case)
Allison
lower (forward) connector
top (rear) connector
Aisin (AF33-5)
top connector
bottom connector (requires J-35944-440)
Aisin (AF17)
top connector
bottom connector
MU4/MU5
top connector
bottom connector
5L50E
bottom connector
top connector
6T70/75
top/front connector
top/rear connector
6T40/45
top/front connector
rear connector
6L50/80/90
bottom connector
top connector
AF40-6
top connector
bottom connector
2ML70
front connector
side connector

Wow...lots of info...but still doesn't answer the question?:confused:

All I can find is the part number description where one is listed as and inlet hose and the other is an outlet hose but it doesn't say the inlet/outlet to the transmission or the inlet/outlet to the cooler. Just didn't want to have to disconnect one of the lines with the engine running to figure it out. I thought someone that has already put a cooler on would/should know since the only line you should be hooking it up to is the one going back to the transmission(if you're not bypassing oem cooler).

Is there a diagram with this info to make sense of it?? Thx.

Under each transmission heading there is two connectors listed. the first one listed is out of transmission into cooler. Second listed would be out of cooler returning to transmission. For eg. a 200r4 the top connector on transmission would flow in direction towards cooler. the bottom connector returns from cooler to transmission.

Got it. So it looks like I was right; bottom line at the trans is the outlet going toward the radiator/cooler, which according to the diagram, goes to the driver side of the radiator.

I swear that when I had mine disconnected, the hose at the bottom left of the radiator was the return line to the transmission.

so looks like my diagram is correct then