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WJ Transmission Cooler and Line Routing

92K views 49 replies 20 participants last post by  WJ60 
#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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#33 ·
So from what I have gathered, in the 2004, 4.0, WJ, ONLY it uses the radiator in it's entirety for the the coolant. The splits the AC condensor in half for the AC system and the transmission fluid cooler.

There weren't any oil coolers on the WJ's to my knowledge.
 
#34 ·
The only thing I can figure out is they kept the same AC condensed and if you had the 4.7 the aux cooler portion was for the powersteering fluid. If you had the 4.0 it became the trans cooler. And the 42 behind the 4.0 needs all the help it can get.

Both 04's I have have the tow package and no extra cooler which also falls in line with a how to tow PDF from Chrysler that says no aux cooler needed.
 
#35 ·
My '04 Overland with the 4.7HO definitely has a trans cooler in the radiator because one of the fittings has been leaking since I bought it. There are fittings on the top and bottom of the passenger side of the radiator with hardlines that run down to the trans. It's damn near impossible to get to the top fitting though, which I need to so I can put some teflon tape on it or just plug it and run an Aux cooler instead.
 
#36 ·
dcorn said:
My '04 Overland with the 4.7HO definitely has a trans cooler in the radiator because one of the fittings has been leaking since I bought it. There are fittings on the top and bottom of the passenger side of the radiator with hardlines that run down to the trans. It's damn near impossible to get to the top fitting though, which I need to so I can put some teflon tape on it or just plug it and run an Aux cooler instead.
Yes for the 4.7 that is the only trans cooler. And I'm pretty sure its the same for all V8's with the hydraulic cooling fan.
 
#40 ·
Transmission fluid only runs through the condenser in the late 2004 WJ with the 4.0 engine.
Power steering fluid runs through the condenser in the late 2004 WJ with the 4.7 engine.
 
#41 ·
snobrdrkid07 said:
Transmission fluid only runs through the condenser in the late 2004 WJ with the 4.0 engine. Power steering fluid runs through the condenser in the late 2004 WJ with the 4.7 engine.
to be honest every 99+ 4.0 owner ought to think about getting the condenser assembly for the later model WJ's and the tubing (junk yard or dealer) and use that as the Aux Trans cooler. To me it's a better setup but will cost some money to install it.
 
#42 ·
So
snobrdrkid07
You had a right up about this.
and you did mention the routing of the trans cooler line but i don get it.

I want to ask, , ....the two skinny lines, with the rubber hoses, I see one has a valve type thing right before the hose. on my jeep 2001 jeep 4.0 6cyl WJ is just the same,/ the bottom line.
Which line from the radiator connect to that one with the valve.

Question
Lines from the radiator upper/lower connect back to which skinny rubber hose, the top with the top and lower with lower or vs. please help
 
#43 ·
WJ transmission cooler and line routung

So does the upper radiator line connect back to the upper transmission line with 3.8 hose. My radiator only has 2 lines and the coolant filler neck is on the driver side. all diagrams I see is talkng about the oil cooler that sits in front of the radiator.

I just want to know for 2001 grand cherokee leardo 4.0 WJ, does the upper hose/lower hose from the rasdiator connect back to the upper radiator line with upper trans line and lower line with lower trans line.
Snobrdrkid.. help a girl out
 
#44 ·
The metal fitting between the hard line and the rubber line is a check valve. That line is coming from the transmission, to the cooler, and the other line is the return.

The transmission cooler from the factory, is a separate cooler inside the radiator. A liquid to liquid cooler.

On my 4.0 Jeep, I added the aux cooler between the output side of the factory cooler, and then from the aux cooler back to the transmission.
 
#46 ·
I was curious why there was 3 pages for a trans line routing thread so I had to look. I see the 04 upgrade caused some confusion. Over the years I have noticed that lots of people want to install a trans cooler but nobody ever installs a trans temp gauge. On my old Chevy square bodies it is the same. I put a temp gauge on mine and the trans never ever gets near hot; even while plowing snow for an hour. You have to really tow heavy loads in the mountains to get an automatic trans to get hot. I would always install a gauge before installing a cooler to see if a cooler is even needed.
 
#47 ·
Yes. JRT 403, I have 2001 grand cherokee laredo 4.0 6 cyl. takes 4 oxygen sensor, I believe made in California. I dont see to hooks on Jeep... it this all means any thing. But yeah on 2001 also.. the trans oil cooler lines connect from the radiator to the transmission.
 
#49 ·
Any one.......
looking at the diagram WJ 60...., has of 4.0 6 cyl. transmission routing line pic
Does the upper hard steel line from the radiator look like it connects with the lower hose of transmission lines and the lower line from radiator line into the top trans mission line? That's what I see...
 
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