Installing a trans cooler onto a '96 XJ 4.0 w/ AW-4 transmission, and in trying to identify which trans line is which I started the engine from cold, pulled it up against a wall and let it rest there in drive, and felt which line got hot first. Although both got warm together it seems like the top line, or the one entering toward the front of the transmission, got hotter. So I would assume that one is the return, and the other ending further back on the transmission is the out. Does that sound right?

Second, most accounts of installing this cooler advise placing it directly in front of the full time fan. Sounds logical. But just now I read an account of that installation position causing someone's engine temp to begin to rise too high, I would assume because of the restricted airflow. Is anyone else seeing this engine temp problem after doing the same install? Should I consider installing it further over toward the center?

And last I'll be doing a simple splice into the soft part of the return line w/ a brass barb. Any advice on routing the lines from there to the cooler?

 

Bottom line on radiator is the pressure line, top is return. You can verify this by looking at the crimped spot where the hard metal lines goes to rubber hose, the line with the high pressure crimp is the pressure line. The pressure line should be the one on the front side of trans, return should be on the back side.

I put mine on driver side or radiator as the out side, front most unit, so it's in front of AC condensor. Then I routed my lines out the top of cooler and along the side and around radiator. I also have a trans temp Guage and have no issues with the trans or engine overheating with it this way. Even when towing a car trailer (which i probably shouldn't be doing in the first place. Lol).

And one last thing, I completely bypassed the stock radiator trans cooler and use only my aftermarket trans cooler. But I blocked off the radiator cooler in case I ever decide to use it in future.

 

You're close on picking which line is the output and return line on the trans, but you've actually have it reversed. That hotter line on the front of the trans is the output line and the one that is at the back of the trans is the return line.

I mounted mine in front of the clutch fan and haven't had any problems. I'm considering moving it over to the electric fan side since my trans doesn't seem to warm up much. I have a gauge installed on the trans output line and it shows that it only gets to about 125 F.

I did the same as far as connecting mine in. I have the fluid going to the heat-exchanger first and then to the trans cooler. I actually ended up removing the crimped end on the hard line and using a compression to barb fitting.

I hope this helps answer some of your questions.

 

in winter the trans may never get up to temp. one reason for trans "cooler" in rad is to stabilize temp in the running gear,designed to run hot,(not too hot!) so the trans actually gets warmed up by the rad "cooler" i read about this somewhere a while ago?

 

interesting. That explains why my trans always seems to be a bit cold unless towing.

 

Correct. It is a heat exchanger.

 

The way I remember it is, R&R. Rear is Return.

 

AW4 cooler line diagram. Blue is return line. Front line is the hot/out line, it is closest to torque converter.