Power steering cooler using radiator trans cooler?

I have to front end of my Jeep torn down due to a frame stiffener upgrade and figured I'd work on the cooling system while i'm at it. I have an aftermarket HD upgraded radiator (made for an XJ, obviously) and it has a beefy transmission cooler in front. The radiator also has fittings on the driver side of the core where the stock transmission cooler lines would attach, but they are plugged and I figured why let them go to waste?

The aftermarket trans cooler is plenty big for my AW-4, but would it be beneficial to run the return line from the power steering gearbox through the built in cooler in the radiator then back to the PS reservoir? I have a bone stock power steering circuit that pushes 33"s & 35"s.

My Jeep runs at 180 degrees at all times unless I am climbing a steep grade for a long period of time where it may climb to 220 degrees. I have never had issues with the power steering, nor has it ever over-heated or burst a line. I was just curious if the cooler would actually be beneficial to prolong the life of the pump and gearbox.

Well, from everything I've come across when researching the matter, you should run the transmission line through the transmission cooler and through the radiator, because in winter and during warm up the transmission fluid will be warmed by the radiator. The AW4 operating range is from about 110 to 170 IIRC so it needs to get into that range. I have that system and I use a transmission cooler from a Ford Bronco II from the junkyard for a power steering cooler. I never had an issue either but about 3 or 4 years ago I put it in with the hopes that it would make my pump last longer. I put it under the radiator behind the bumper in one of those 3 large oval holes cut into the cross member there.

Oh and I rock a camo XJ also. Sweet.

I'm curious about the "normal" operating temperature of the PS fluid in the XJ vs. what "radiator" cooled PS fluid temperature would be. In other words, would you be heating up the PS fluid running it through the radiator's trans cooler?

It has been my experience that the power steering fluid get pretty hot. I recently had my power steering fluid going through the radiator and I found that it heated the coolant back up just before it goes back into the engine and made it run hot. I disconnected the powersteering fluid from the radiator and now I run it through a separate cooler. I think it would work better if they had designed the tranny cooler to be in the middle of the radiator so that the coolant still has some cooling fins to go through after it picks up the heat from the tranny fluid (or power steering fluid if you have that running through it).

joe_peters said:

I'm curious about the "normal" operating temperature of the PS fluid in the XJ vs. what "radiator" cooled PS fluid temperature would be. In other words, would you be heating up the PS fluid running it through the radiator's trans cooler?

Click to expand...

My thoughts exactly. The only way to accurately tell would be an infrared thermostat gun, which I don't have and don't want to purchase one just yet. We have them in our diesel & HD shop at school, so maybe when summer break is over, I'll see what i can do to hook it up and experiment.

yes a cooler can prolong the life of the power steering pump and box. i drive on old forest service and fire roads with lots of turns and havnt had any problems without a steering cooler but upgraded my steering pump, box and tie rod & drag link last month and installed a grand cherokee auto trans cooler as a steering cooler. i havent checked temps but it runs fine and gives added peace of mind