Like the title says I need help finding the return line so I can hook up my new transmission cooler. I did a search for it and I recall someone saying the return line goes to the back of the transmission but Im not sure If im remembering that correct and dont want to start cutting lines to find out its the wrong one. I think I have a good idea because the return line shouldn't have pressure like the inlet i would think. But any help would be great

 

Yes, "return" is the line at the rear of the trans.

 

Yes the return line is the one that goes to the rear of the transmission. This is because the torque convertor is where the majority of the heat comes from in an automatic tranny. So the hot oil comes out of the convertor at the front of the trans. Are you doing away with the factory cooler? If not, the oil should come out of the tranny, go to the add on cooler, THEN to the factory cooler and back to the tranny. 2 reasons to do it this way-the add on cooler takes away most of the heat so your radiator runs cooler in the heat, the other reason is that in the winter your trans oil will be brought up to the proper temperature more quickly by radiator so it does a proper job of lubing the trans. If you look at the trucks with Super Cooling on them, they are plumbed this way, oil comes to the added cooler and then to the radiator cooler and then back to the trans. For this reason I would recomend keeping the factory cooler unless there is something wrong with it.

 

This is an add on cooler. Nothing wrong with the radiator cooler. I had talked about this before and someone told me to go to the radiator then out of the radiator to the inlet of the added cooler then out the cooler to the return line, reason was because the radiator is hot already so you would be sending hotter oil to the add on cooler and pointless to use the cooler? But if the super cooling system is set up so it goes to the cooler then the radiator cooler that seems to be the right way to go

 

Check the manufacturers' suggested installation documentation. A quick search reveals this:

Cut from here: Automatic transmission cooler guide and installation

Transmission Cooler Quick Guide & installation
The most often asked question is should I bypass the radiator cooler when I install a auxillary cooler.
Most cooler manufactures and automobile manufactures information we have read, recommends installing the coolers In-Series with the factory radiator cooler for maxium cooling efficiency.
So unless the manufactures who have spent 1000's of hours testing different installations are wrong, the suggested cooler installation is in-series......
Transmission > Radiator cooler > Auxiliary cooler > then Back to the transmission.



A second source of info cut from here: Hayden - FAQs

Q. Should the cooler be installed before or after the radiator?
A. Hayden recommends installing the auxiliary cooler after the radiator to return the coolest fluid directly to the transmission. Installing the cooler before the radiator will still provide additional cooling and may be necessary in some difficult access applications.

 

The shop I used to work in routed first to the radiator then to the external cooler and back to the trans.

 

Thanks guys I looked at the way the mfg sugguests and it wants transmission to radiator then aux cooler back to transmission. Thats the way im going to do it since Im sure they know w hats best for there product