Tranny cooler question

If I were to install a transmission cooler, would it be in addition to going to the radiator or would it only have to go through the cooler?

I have some f'ed up tranny lines from a difficult pull and I want to put on a cooler anyhow. If the lines ran in the tranny to the cooler out of the cooler and back to the tranny that would be ideal. I am assuming but have never got a confirmation that the transmission has its own pump? I am a transmission newbie but I need a little help.

I would just mount the cooler under the car or what? where do these normally go? In front of the radiator?

THanks

--Alex

Normally goes in front. This topic gets discussed a lot. I'm sure searching here will get you lots of info, and I know for sure that searching on jeepin.com will too.

Get the biggest tranny cooler that you can fit in front of the radiator!! You don't NEED to have the lines going into the radiator too...but some people usually leave them going through there anyways. Generally, the logic behind keeping that almost useless cooling loop part of the bigger loop is in the winter, it will get your tranny fluid up to temp!!! Seeing as how you live in AL I'd say you really won't have to be worrying about the tranny never getting up to operating temps!!

Do whatever is easiest. If you totally remove the radiator loop, obviously, block off the holes there. If your tranny hard lines are really messed up, just cut them back to where they're not bad, and run tranny hose the whole way up and back!! The pump is in the tranny, no worries there. Do not use fuel line!! It's different than tranny line. The tranny line is specific to deal with tranny fluid, and any autoparts store has it. Get more than you need.

The easiest way to get the hose onto the hard lines is just with a hose clamp. I'd recommend using two hose clamps if you can...just extra insurance.

If you want, you can also get compression fittings onto the hard lines and then put barbs onto the compression fittings and do it that way...but you'll still need to hose clamp the lines to the barbs. I did this method years back before I knew better, and although it worked, it was a waste of parts. I've done many more tranny coolers since then with just hose clamps on the hard lines with no issues at all.

mjma said:

Normally goes in front. This topic gets discussed a lot. I'm sure searching here will get you lots of info, and I know for sure that searching on jeepin.com will too.

Get the biggest tranny cooler that you can fit in front of the radiator!! You don't NEED to have the lines going into the radiator too...but some people usually leave them going through there anyways. Generally, the logic behind keeping that almost useless cooling loop part of the bigger loop is in the winter, it will get your tranny fluid up to temp!!! Seeing as how you live in AL I'd say you really won't have to be worrying about the tranny never getting up to operating temps!!

Do whatever is easiest. If you totally remove the radiator loop, obviously, block off the holes there. If your tranny hard lines are really messed up, just cut them back to where they're not bad, and run tranny hose the whole way up and back!! The pump is in the tranny, no worries there. Do not use fuel line!! It's different than tranny line. The tranny line is specific to deal with tranny fluid, and any autoparts store has it. Get more than you need.

The easiest way to get the hose onto the hard lines is just with a hose clamp. I'd recommend using two hose clamps if you can...just extra insurance.

If you want, you can also get compression fittings onto the hard lines and then put barbs onto the compression fittings and do it that way...but you'll still need to hose clamp the lines to the barbs. I did this method years back before I knew better, and although it worked, it was a waste of parts. I've done many more tranny coolers since then with just hose clamps on the hard lines with no issues at all.

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I would agree about doing searches on here for more info, but i would definetly disagree on getting the biggest cooler you can fit in front of the radiator. Your asking for trouble that way... (engine overheating etc).
If i absoloutly had to put a cooler in front of the radiator, i would probably do one of those ford exploder tranny coolers there.
I put mine inside the front crossmember below the radiator. I also have a taurus fan that is installed in my Jeep, and the lower section of the fan pulls air through the cooler.

As far as how you want to run the lines, its all up to you. Its general rule of thumb that if have colder winters, that you should run the fluid out of the cooler and into the heat exchanger (in the radiator) and then back to the tranny. If you stay fairly warm during winters then you can just go straight to the cooler and back.
Its just as bad to run the transmission with cold fluid as it is to run it with hot fluid, thats why i always recommend no matter where you live to run the fluid through the cooler and then into the heat exchanger and back to the tranny.... but in all reality its up to the end user...

bypass the radiator all together.

R_jeep said:

bypass the radiator all together.

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If you leave the Radiator hooked up, it pre-cools before it hits your Aux trans cooler, and in cold weather it keeps the trans from being too cold.

I think the idea is the other way around.

Trans -> aux trans cooler -> radiator -> trans

Doing this will help keep it from getting too cold in cold weather. Here in california its ok to bypass the radiator, but it would not be a great idea in say .. colorado.

Cooler on my 96. Biggest one I could fit!! Other than the water pump just going out on me, no cooling problems.


Cooler on my 99...not quite as big, but still big, and no overheating problems.

Stallacrew said:

If I were to install a transmission cooler, would it be in addition to going to the radiator or would it only have to go through the cooler?

I have some f'ed up tranny lines from a difficult pull and I want to put on a cooler anyhow. If the lines ran in the tranny to the cooler out of the cooler and back to the tranny that would be ideal. I am assuming but have never got a confirmation that the transmission has its own pump? I am a transmission newbie but I need a little help.

I would just mount the cooler under the car or what? where do these normally go? In front of the radiator?

THanks

--Alex

Click to expand...

The aux cooler typically mounts to the face of the radiator.

The jury is still out on whether the cooler goes in series with the "cooler" in the radiator, or the radiator cooler gets run out of circuit. I'll usually run it out of circuit - preferably with a thermal bypass valve. The idea behind running the OEM cooler in the radiator tank is to help bring the tranny fluid up to temp in a hurry, but then it inhibits cooling once it does get there, which works against the added cooler.

The "thermal bypass valve" works to take the cooler out of circuit at temperatures below ~190*F, then opens to up allow flow through the cooler. It cycles back and forth to maintain fluid temperatures of ~190-200*F, which is right about where you want them anyhow. I know B&M used to make such a valve, and I would think that the idea has long since spread to other outfits as well (like FlowKooler, Flex-A-Lite, and Hayden.) It's a fairly common speed shop item, so you might want to start there (locally) or with Summit or Jeg's (online.)

5-90 said:

The aux cooler typically mounts to the face of the radiator.

The jury is still out on whether the cooler goes in series with the "cooler" in the radiator, or the radiator cooler gets run out of circuit. I'll usually run it out of circuit - preferably with a thermal bypass valve. The idea behind running the OEM cooler in the radiator tank is to help bring the tranny fluid up to temp in a hurry, but then it inhibits cooling once it does get there, which works against the added cooler.

The "thermal bypass valve" works to take the cooler out of circuit at temperatures below ~190*F, then opens to up allow flow through the cooler. It cycles back and forth to maintain fluid temperatures of ~190-200*F, which is right about where you want them anyhow. I know B&M used to make such a valve, and I would think that the idea has long since spread to other outfits as well (like FlowKooler, Flex-A-Lite, and Hayden.) It's a fairly common speed shop item, so you might want to start there (locally) or with Summit or Jeg's (online.)

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I am not sure on this one. If the XJ works anything like a full size truck, then I would disagree. large trucks we see the trans temp will run cooler with the radiator first in line, trans fluid coming out of the T.C well exceeds the 210 in your radiator, So when your T.C is getting a workout and the fluid coming out of it is 225+, you get a slight drop before it hits your cooler, and like you said, It also heats it up quick which is also important, especially in a stock vehicle where you are locking to achieve constant Shifting.

FordGuy said:

I am not sure on this one. If the XJ works anything like a full size truck, then I would disagree. large trucks we see the trans temp will run cooler with the radiator first in line, trans fluid coming out of the T.C well exceeds the 210 in your radiator, So when your T.C is getting a workout and the fluid coming out of it is 225+, you get a slight drop before it hits your cooler, and like you said, It also heats it up quick which is also important, especially in a stock vehicle where you are locking to achieve constant Shifting.

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Which is why I brought up the thermal bypass valve - allows the transmission fluid to get up to temp without the cooler in circuit, and bypasses the cooler if the fluid gets too cool during use. I'd rather run a setup like that than run fluid through the radiator - if the fluid is hotter than the coolant, then it's an extra thermal load on the radiator.

Yes, having the cooler in front of the radiator is also an extra thermal load, but it's actually quite a bit less than heating up the coolant directly!

So I have another side question while we are on the cooler/rad/tranny topic. I have procured some m14-1,5 plugs to replace the large lugs that have the "quick disconnect" for the hoses. I will replace these QD's with the plugs that have a 3/16 barb on the end and replace the stainless lines with rubber tranny hose.

Is this a bad idea running only rubber hose and no steel? I don't really see it as an issue. Rather than the QD's there will be hose on barb with a hose clamp or two per side. this is how my cooler accepts line so I figured it would be kosher.

Stallacrew said:

So I have another side question while we are on the cooler/rad/tranny topic. I have procured some m14-1,5 plugs to replace the large lugs that have the "quick disconnect" for the hoses. I will replace these QD's with the plugs that have a 3/16 barb on the end and replace the stainless lines with rubber tranny hose.

Is this a bad idea running only rubber hose and no steel? I don't really see it as an issue. Rather than the QD's there will be hose on barb with a hose clamp or two per side. this is how my cooler accepts line so I figured it would be kosher.

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Given proper hose routing and retention, it's not that big of an issue. Pressure is minimal (but I'm sure you meant 3/8" barb, not 3/16". 3/16" won't give you enough flow for the cooler to be useful...)

Keep them tied up out of the way, and make sure they stay there, and you'll be fine. Also, be sure to keep them away from the exhaust (should be obvious, but I've had to fix bad hose routing issues before...)

Yeah I meant 3/8........I was talkin to dad on the phone about it and he made me furious saying that OEM is the way to go and not change anything. Anyhow, I now have clearance on my idea......and if I eff it up, then I the one who has to fix it, right.

And if I have an old coolant temp sender can I plumb that into a T line and run the wire to my temp gauge and have a switch to control which line I read from ( coolant or trans)?

Every automatic jeep that I've ever taken a peek at was leaking from the crimped part where the hard line connects to the hose......F OEM stuff!!! Back yard engineering does it better!!!


Are you talking about eliminating the "quick discos" that are up by the radiator (yeah, ditch those POSs) or the "quick discos" that put the hard lines into the actual tranny?? (if those work, keep em).

If the quick discos at the tranny aren't leaking....don't touch em!! I've never touched em, always just cut the hard lines to remove the tranny....so can't tell you anything about em. They look like more of a PITA than they're worth though.

Sorry but your dad is right. Extensive testing was done in both hot and cold climates and the OEM set up is the best way for your XJ. Chrysler has more money invested in RND than anyone on this forum. Listen to Dad he has more Knowledge than you. Use the OEM Cooler or maybe one a little bigger and run the lines according to manufactures suggestions. I have the OEM set up for my XJ and no problems in cold climate. Lake Tahoe is 7-14 below in the winter sometimes.

Jumping in, I have to agree with the above comment about them having a Large budget. but they also want to cut costs as much as possible.

by dropping the tranny temp 10* - 15* may add a few more years to the life of teh transmission. I am sure Jeep wont say it but any Auto Maker mostly cares about things working for the length of the warranty. after that they say its normal ware and tare.

I find it hard to beleive that RND would put the Government, FBI, FNG, Forestry Department and Water District at risk. Those are just some of the Government funded services that had contracts with Chrysler. They all used XJ's in the most extreme enviroments.

Usually those vehicles get equipped with extra features and cost more. That’s why its nice to find a used Gov. Car that has not been beat to death, but that hard to do some times.

I do believe that R&D does not want to put people in danger (I don’t know if having the transmission temp run higher would be considered danger) but I know the CEO's and people looking for a profit are looking at the most ways to squeeze quality out of parts.

If it means saving 20 bucks a jeep for a 10% smaller cooler that runs the trans at 170* normal op in place of 160* they are going to go for the cost cutting. Will the higher operating temp be a problem for "normal" driving? No but in 4x4 or other situations (like the Gov.) what they do is slap on a cooler and a tow hitch and calls it a towing package and charge you for it.

Skip the radiator/trans cooler. It's a retarded design and just stick extra heat into the engine coolant and slows the cooling process.

I've been running mine that way and I have no problems in the -30 - +100 deg SD weather. You want the trans fluid to warm up let it run for a bit longer.

And bigger is better to a point, area is only part of it, get one with the biggest tubes you can find as well.