Auxiliary Tranny Cooler Question

97 XJ Auto 4.0L Police Package

seems like i have a leak in the fins of my auxiliary transmission oil cooler that is mounted in front of my radiator. i am going to replace it but i was wondering since this is an 'auxiliary' is it absolutely necessary if this is a daily driver that does no towing?
was it stock or installed because its a police package?
doesnt the tranny oil somehow go through the radiator to cool also?

dumbagain said:

97 XJ Auto 4.0L Police Package

seems like i have a leak in the fins of my auxiliary transmission oil cooler that is mounted in front of my radiator. i am going to replace it but i was wondering since this is an 'auxiliary' is it absolutely necessary if this is a daily driver that does no towing?

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Its a good idea to keep it, I can guarantee it will extend the life of your tranny even if you do not tow

dumbagain said:

was it stock or installed because its a police package?

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Most likely it was added

dumbagain said:

doesnt the tranny oil somehow go through the radiator to cool also?

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Most likely and its a good idea if you live in a colder climate to put a little heat back into the tranny. If you live in a warmer climate I wouldn't worry about it.

so the tranny oil passes through the radiator to WARM it?

dumbagain said:

so the tranny oil passes through the radiator to WARM it?

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No not exactly! In cold weather the engine will heat up before the tranny does in most cases so the engine coolant will help put a little heat into the in-radiator cooler and warm the tranny fluid to a good operating temp. This is only useful in really cold climates. Otherwise just bypass the radiator cooler and go right into/out of an axillary cooler.

xjtrailrider said:

Its a good idea to keep it, I can guarantee it will extend the life of your tranny even if you do not tow.

Most likely it was added

Most likely and its a good idea if you live in a colder climate to put a little heat back into the tranny. If you live in a warmer climate I wouldn't worry about it.

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If it's a little 2" by 10-12" cooler, it's likely stock, especailly if it has the lame quick discos. If it's something like 6 or 8" by 10-12" then it's added. It is SUPER easy to add a better cooler. While you are at it you can replace the cooler connections to just regular clamps. A decent cooler will run about $40-50.

dumbagain said:

so the tranny oil passes through the radiator to WARM it?

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Yes..the tranny lines go thru the radiator to warm it. Optimal operating temp is between 125-175 or so. I have a temp gauge on mine (and no passsage thru the "heat exchanger" in the radiator) and during the winter it sometimes never gets over 125 degrees. Then again I live in NorCal and cold here is ~~30F, summer is 90-100.

I have a Hayden cooler on mine, hottest it's ever gotten is 260, towing, on a 11 mile long 6% grade in 102 degree weather. When I topped the hill it quickly came down to 150.

its the small stock cooler for sure. i probably should have gotten a bigger one but i found a junkyard replacement for real cheap figuring its worked this long and i wont be towing with this xj.
the old one was leaking a lot of fluid per week so i just want to avoid that. i will probably cut out the discos and use flaring, clamps and barbs to reconnect before the discos start dripping. oil pressure is low right? so clamping is find to do?

There is pressure, but not as much as people think. It's pushing fluid but it's not likely to burst a line or the like. I just have clamps on all my connections and it hasn't dripped a drop in 3 years (OK, maybe a drop).

it is necessary to get a tubing flare kit and flare the ends where the atf hoses will attach or would a good fuel injection type clamp do the trick?

A hose clamp should be fine. I never had more then a drop or two come out of mine, and that was with a old crappy leftover hose that was supposed to be a temporary splice. If you want, just double the clamps.