Trasmission cooler bypass radiator?

[rmonte4812]

Hi There, im going to be installing a new bigger transmission cool and was wonder if I should bypass where it goes in to the radiator. I live in Phoenix AZ so cold weather isn't an issue. Just wondering what peoples thoughts are on this. The jeep has 32's and Ill be starting to tow a small trailer in the future

Thankseace:

 

[z06elmo]

are you installing a bigger transmission or installing a bigger transmission cooler? If the latter then you can bypass the radiator (i'm not sure how much of the radiator is used for cooling).

 

[ParadiseXJ]

The only feasible function of the radiator loop is to WARM the tranny fluid in cold weather, it holds about 2-3 cups of fluid. It is a heat exchanger, not a cooler.
Just the left tank holds the fluid in a foot long, 1"-1 1/4" tube bathed in hot coolant.
[how could a radiator running at say 190 cool tranny fluid to ~125 or ~150 degrees?]

I've had the loop deleted from my XJ w/AW4 for several years now with no ill effects. I added a 10"x12" COOLER for towing and hot weather. Right now I have to turn it off manually with a gate valve in the winter. But all summer long it's working. Average summer temps here run around 90-100 and only about 80-90 up in the surrounding mountains. My average tranny temps run 125-150 degrees.

...and no, it doesn't matter IMHO which hose the gauge is on...I said "average" temps.

 

[OutkastBoss]

the stock aux cooler left the radiator exchanger so I did too...

 

[carves]

The only feasible function of the radiator loop is to WARM the tranny fluid in cold weather, it holds about 2-3 cups of fluid. It is a heat exchanger, not a cooler.
Just the left tank holds the fluid in a foot long, 1"-1 1/4" tube bathed in hot coolant.
[how could a radiator running at say 190 cool tranny fluid to ~125 or ~150 degrees?]

I've had the loop deleted from my XJ w/AW4 for several years now with no ill effects. I added a 10"x12" COOLER for towing and hot weather. Right now I have to turn it off manually with a gate valve in the winter. But all summer long it's working. Average summer temps here run around 90-100 and only about 80-90 up in the surrounding mountains. My average tranny temps run 125-150 degrees.

...and no, it doesn't matter IMHO which hose the gauge is on...I said "average" temps.

X 2 ....

Bypassed heat exchanger,
10x12 stacked plate cooler - mounted behind the grille and in line with the clutchfan,

and my tranny sump temps are about 140*f/150*f in 0*f - 110*f weather .... and about 170*f/180*f on a hill with a lump of a trailer on behind.

Just takes a few extra minutes/miles to get up to temp ... if Im silly enough - to be out and about in 0*f - 20*f weather ... :laugh:

Very peaceful in the cab not having the 190*f warning buzzer not going off anymore ...



Got any pics of that U.S. LHD heat exchanger Paradise ??

This is the little bit of junk they jammed in ... the hot side ... of RHD radiators. .... Which is a real handy setup for 70* - 110* weather

 

[hubs97xj]

I have not actually seen the exchanger before. I'm even less impressed now.

 

[ParadiseXJ]

I have not actually seen the exchanger before. I'm even less impressed now.

I've thought about making an OBCM (aka On Board Cappucino Machine) out of mine. Just have to figure a way to route some tubing in to the cab.

:laugh:

 

[techno1154]

X 2 ....

Bypassed heat exchanger,
10x12 stacked plate cooler - mounted behind the grille and in line with the clutchfan,

and my tranny sump temps are about 140*f/150*f in 0*f - 110*f weather .... and about 170*f/180*f on a hill with a lump of a trailer on behind.

Just takes a few extra minutes/miles to get up to temp ... if Im silly enough - to be out and about in 0*f - 20*f weather ... :laugh:

Very peaceful in the cab not having the 190*f warning buzzer not going off anymore ...



Got any pics of that U.S. LHD heat exchanger Paradise ??

This is the little bit of junk they jammed in ... the hot side ... of RHD radiators. .... Which is a real handy setup for 70* - 110* weather

That is a really interesting cooler/heat exchanger pictured there. I know water passes around the outside but what passes in the center hole? From the angle of the picture it look like water also. Am I correct? Is there a tube inside a tube with water around the outside and down the middle also?

 

[rmonte4812]

Thanks for the help. I kinda figured it went through the radiator to warm it up quicker and not cool. And thanks for mentioning which side you put it on, that was my next question.

 

[carves]

That is a really interesting cooler/heat exchanger pictured there. I know water passes around the outside but what passes in the center hole? From the angle of the picture it look like water also. Am I correct? Is there a tube inside a tube with water around the outside and down the middle also?

Essentially its just two pieces of tube joined at the ends.

Coolant passes by the outside ... and thru the centre.

Was most disappointing finding that thing, years ago - instead of a tube or two, running across the rad core ... when I pulled an old radiator apart looking for the factory, inbuilt, "cooler" mentioned so often in the FSM and forums ... ..


Keep in mind it is dangled in 200*+ coolant in a RHD .... so it may perform slightly better ... as a "cooler" ... in the other end of the radiator in a LHD.

 

[OutkastBoss]

My motor actually runs cooler now with the cooler trans fluid going through the radiator exchanger .
Does your guys with it bypassed run cooler as well i suppose?

One of my main reasons for keeping it was that while it does see hot temps , once every other year its in the mountains in colorado in December.
and it helps get it up to operating temps..

there was a thread where the pros or cons were discussed and it seemed there was no clear answer as to either way being any better than the other .. just everyone saying their way was better because theirs worked fine.

Even if i lived where it never got cold i couldnt imagine doing anything that would make it not as versatile in all conditions.. besides i like to wheel different locations and states .

it can get pretty hot in Stl sometimes (100 plus sometimes) and even when doing some towing or wheeling my trans temps stay low so i just dont see it being a benefit to remove it besides less fittings and attachments.
I recently geared down so i expect it to run even cooler this summer

 

[techno1154]

Essentially its just two pieces of tube joined at the ends.

Coolant passes by the outside ... and thru the centre.

Was most disappointing finding that thing, years ago - instead of a tube or two, running across the rad core ... when I pulled an old radiator apart looking for the factory, inbuilt, "cooler" mentioned so often in the FSM and forums ... ..


Keep in mind it is dangled in 200*+ coolant in a RHD .... so it may perform slightly better ... as a "cooler" ... in the other end of the radiator in a LHD.

That is exactly what it look like in the pics and I cannot explain my dissapointment in the lack of a proper cooler in the XJ. My XJ have been neglected/not been used since 2009. My plans for the cooling system includes fitting a radiator that do not have the cooler in it. I will opt for a remote cooler with an independant fan.

I am willing to bet that most XJ owners who have problem keeping the 4.0L cool also have the AW4 transmission. No matter who you ask about the AW4, the answer is always the same,... it is reliable but runs way too hot.

 

[OutkastBoss]

:dunno: I Never had any issues with overheating. i did the cooler to hopefully prolong the life of the trans by running it cooler.
(and i tow with mine relatively often)

 

[ParadiseXJ]

Very peaceful in the cab not having the 190*f warning buzzer not going off anymore ... Got any pics of that U.S. LHD heat exchanger Paradise ??

This is the little bit of junk they jammed in ... the hot side ... of RHD radiators. .... Which is a real handy setup for 70* - 110* weather

It's just the same as the RHD. It's just the tube, running down the inside tank of the left side of the radiator. Note the fittings on each end are the tranny line fittings. So coolant on the outside, tranny fluid on the inside. That's why it can't be called a "cooler". If the coolant is ~200F and the tranny wants to be ~150F or so +/- 50 degrees.

The "pressure" going thru that tube is really minimal to move the tranny fluid. It's enough to empty your tranny if there is a large leak, and enough to CAUSE a seeping leak. But, if the end seals on the tube fail, you'll have tranny fluid in the coolant and worse, coolant in the tranny. A sure way to ruin an AW4. Another reason to bypass the tube unless you live in cold country. Cold around here is +30F, just barely cool by Minnesota or Michigan standards.

Of course the temps go down the further up the hill you go. 35 miles away at elevation 6000 ft. the temp is about 15F with a few feet of snow.

 

[akelts]

I bypassed mine a couple years ago....no problems since then. Living in the desert I am more concerned with keeping things cool and not so worried about getting them up to operating temp. My trans temps are MUCH improved especially on long uphill grades.

 

[1993jeep]

So if I cancel the trans oil lines going into the water radiator and just make them go into trans oil cooler radiator in the front it will cool the trans better?

 

[garr]

Has anyone set it up so they can switch the rad tranny cooler/heater in/out to maintain the best ATF temperature year round ?
For example, switch it in service from December to April & Bypass the rad & use the external cooler for the rest of the year ?
Have the best of both worlds cooling when needed & Heating when needed!

 

[OutkastBoss]

Has anyone set it up so they can switch the rad tranny cooler/heater in/out to maintain the best ATF temperature year round ?
For example, switch it in service from December to April & Bypass the rad & use the external cooler for the rest of the year ?
Have the best of both worlds cooling when needed & Heating when needed!

seems like a huge waste when plenty of people have used both their aftermarket cooler and the radiator exchanger and have no problems in any weather!

however the stacked plate aux cooler I used supposedly bypasses the cooler internally when the fluid is cold.

when I did mine I changed all the lines to jegs pushlock hose with AN fittings and a temp gauge and a oil filter (wix 51515) for more volume and a real filter..

if your trans ever overheated and got hotter than the motor the exchanger would help cool to some extent.. If it got that hot w an aftermarket cooler on you would see it on your temp gauge and probably let it rest to cool down anyway though ( I think I would but I've never had to)

Paradisexj mentioned earlier in this thread something about his having a gate valve to turn off his cooler for winter ..

 

[OutkastBoss]

What temps are you guys getting with it bypassed?
mine reads from right after it comes out of the trans. and is grounded at the sender.

in the winter mine gets up to about 100 and not much more

And in the summer it usually runs at about 150 but if its real hot and im towing (missouri has hills) ive seen it get up to 160 (with stock gearing and 31's)

One timeI pushed it really hard in the backroads (very hilly) with two 48" commercial mowers on the trailer (only time i ever towed more than one with the 'rokee) and it got up to 170..

and meanwhile my motor that allways ran at 210 runs a noticable touch cooler almost all year and on the hot days get up to its old 210 with the trans at 150 under normal conditions

I beleive the cold side of the radiator should be like 180 190

 

[garr]

seems like a huge waste when plenty of people have used both their aftermarket cooler and the radiator exchanger and have no problems in any weather!

however the stacked plate aux cooler I used supposedly bypasses the cooler internally when the fluid is cold.

when I did mine I changed all the lines to jegs pushlock hose with AN fittings and a temp gauge and a oil filter (wix 51515) for more volume and a real filter..

if your trans ever overheated and got hotter than the motor the exchanger would help cool to some extent.. If it got that hot w an aftermarket cooler on you would see it on your temp gauge and probably let it rest to cool down anyway though ( I think I would but I've never had to)

Paradisexj mentioned earlier in this thread something about his having a gate valve to turn off his cooler for winter ..

I have no intention of doing this I was just curious,
I installed a B&M cooler inline after the rad that also supposedly bypasses the cooler internally when the fluid is cold & Have no issues at all. I installed a magnefine inline filter for a little extra insurance.