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Discussion Starter · #1 ·
Hello Everyone. I have been reading though threads and threads about the Transmission Coolers in the WJ's. Well I have come to the conclusion that there really have not been any definitive answers because of the variety of different setups. Depending on what engine, what year, and if you have a tow package or not, can determine your setup.

For Example: My 2004 WJ with the 4.0 and the Factory Tow package (Including: The Mechanical Fan, 3.73 Gears, The Tow Bar, and the 7-Pin Harness). As for the transmission cooler from the 2003 and 2004 years according to the FSM there was no Auxiliary cooler because it was determined that one was not needed. BUT my transmission oil cooler is in the A/C CONDENSER and is NOT in the Radiator. (have pictures to prove below). While some o

So to my question. I am adding an auxiliary cooler because I am going to be towing and use my WJ harder the its "Grocery Getter" name. I planned on installing the Aux Cooler AFTER the factory cooler as recommended. BUT, for what ever reason, I can not decide or figure out for the life of me, which line is the RETURN line from the transmission cooler, back to the transmission. There is one line with a "check" or back-flow preventer valve. To me that would logically be on the line coming FROM the transmission and too the cooler to keep the radiator "full" so no priming is needed in the system.

Picture Time:
Here are the transmission cooling lines going to the AC Condenser. (Driver Side)


These are the AC lines going to the AC Condenser. (Passenger Side)


You can see here that the bottom line has the "valve" on it. (Next to the oil pan, looking up towards the bottom of the engine


Then up to the AC Condenser Connection:


So finally, does anyone know which line is the return line, specifically on the 2004 and possible 2003 WJ with the 4.0? Thanks
 

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Discussion Starter · #3 ·
Well I went ahead and just dove into the project and found what I was looking by trial and error!

Well got it all done today!
Here are all the pictures and captions, here we go!


Figuring out how the heck I am getting the aux cooler in there!


Getting the hoses on the aux cooler.




Getting the Cooler in the Grille and routing the lines.








Side Shot. I did not want to use those radiator ties that go through the fins. I did not thing that was the best for them. So what I did was zip tie it basically bheind the grille. I added tonight the foam sticky pads on all metal on metal on contact so there is not scarping and rattling :thumbsup:.


Fluid - I had my friend who is President of the Jeep club and smelled it and looked at it and said it was okay. Also went to two other AAP and had them look at it, they both said it was okay and that I should not worry.



Underneath. I found that that factory cooler OUTPUT line is opposite to what some of the diagrams were saying. The line with the BLACK hose half-way on it, was the exit for the factory cooler. I found this out by connecting some extra hose to that port (I had picked this one because it was cooler, ran it for a few minuets) then with that hose, I started it up and then put the Jeep in N for a split second and sure enough tons of fluid was spewing out! So that took care of that! My routing is as follows --> Feed from transmission, goes through the factory cooler, out the factory cooler, through the aux cooler and back to the transmission! The differences in 'feel' of temperature in the lines is immensely more then stock! The Aux cooler is doing its job very very well!


This is showing how I routed the lines over the power steering pump. They are not rubbing on anything and they are away from things that get very hot.







Showing the new lines connected to the stock ports. Everything is routed so there are NO tight bends.



 

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I added a cooler about 7 years ago - Still have it today. After many many years of hard work and abuse I am still running the original tranny, no rebuilds either. OD is almost to 200k - A tranny cooler is one of the best things you can do to keep your transmission from blowing up.
 

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Discussion Starter · #7 ·
You are welcome guys. If you have any questions, post them up!!
 

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Discussion Starter · #8 ·
I added a cooler about 7 years ago - Still have it today. After many many years of hard work and abuse I am still running the original tranny, no rebuilds either. OD is almost to 200k - A tranny cooler is one of the best things you can do to keep your transmission from blowing up.
Oh I agree, I should have added my cooler years ago! I have noticed improvements in the shifting with the cooler. When I am lugging around in the city during the summer, without the aux cooler, it would start to get sloppy because it would be getting hot. Now, it is keeping it much cooler and happier!
 

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Where did you get this aux cooler? I know you have an '04, but on my 00, I believe the stock cooling lines run the radiator, not the A/C condenser. I wonder if it will pretty much be the same for me...

Great write-up though, nice and practical method.
 

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Discussion Starter · #10 ·
This is the exact cooler that I bought here

Right, I do not know which year Jeep switched from the transmission cooler being in the radiator to the AC condenser. The 2003 and 2004 years had the transmission cooler in the AC condenser for sure.
 

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Great thread and very helpful. I have a 2003 GC with the 4.0L withOUT the trailer towing package. My factory transmission lines go to the radiator. They do not go to the AC Condenser. That said, the rest of my lines look just like yours. I'm installing the B&M cooler. You don't have to use zip ties. If you take your time, you can bend the supplied brackets and mount them to existing bolts. Start off by tracing the brackets on some cardboard. Bend the cardboard until you have shapes that will work. Then transfer the bends to the actual brackets. The easiest way is with a bench vice and a hammer. But, you could do it other ways too.
 

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Discussion Starter · #12 ·
Thanks. I was glad that it was able to help you out. On my cooler though. The whole entire mount tab was running down the entire length. Would have sucked to bend all of that.
 

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Discussion Starter · #14 ·
86cj74.2L said:
On the V8 the cooler in the condenser is for the power steering fluid.
For the V8's with the hydraulic cooling system. That's why they had a separate transmission cooler. Correct?

I'm not as familiar with the v8 setups.
 

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Discussion Starter · #16 ·
Cool, thanks for the pictures! The more you know. :)
 

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Replaced leaking hoses

You are welcome guys. If you have any questions, post them up!!
Alright kid07, I have a 03 WJ and the cooler is in the radiator for mine, the only thing that confuses me is that the line that has that bulky adapter (or bottom line under the oil pan) goes to the bottom of my cooler. Then flows upward then back down to return to the transmission. Does that make sense? Wouldn't that create a lot of unnecessary pressure to push fluid up?

And finally if i but the tow bumper on, should i go aftermarket cooler anyways?

Thanks!
 

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Discussion Starter · #18 ·
I believe it flows upward so it does not all drain out when you park the Jeep, in conjunction with the check valve. If there was no back flow preventer, the check valve, all the fluid would run back and would have to refill the cooler every time you start the Jeep.

If you are going to be doing any towing or want to keep your transmission cooler, (which can never hurt to keep it running cooler), I definitely recommend a cooler.
 

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You are welcome guys. If you have any questions, post them up!!
First of all, thanks for posting this. I have a few question though. My 2002 4.0L is a bit different in that it has the transmission lines going to the drivers side of the radiator (cooler built into radiator). From what I've read on this thread, the trans fluid comes from the trans to the bottom of the rad/cooler to the top of the rad/cooler then back to the trans.
Is this correct?
If this is correct then the only trans line I will splice my cooler into would be the one WITHOUT that check valve on it?
Also, could someone post pics of any "test ports" on the transmission in order to hook up a trans temp gauge?
Just want to be sure, since I have very limited time to work on my Jeep.
Thanks dudes.
 

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Discussion Starter · #20 ·
If you follow the same procedure you should be pretty good to go. You can check the flow the same way as I did by putting it in N for a half second and seeing where fluid comes out. Make sure you have a quart or two of transmission fluid to fill it up when you are done.

As for routing the lines and flow, it should all be in the first post.

I don't have a temperature gauge for the transmission fluid.
 
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