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Plumbing an aux. trans cooler correctly

T

Tonybeirut

NAXJA Forum User
Location
Lebanon
From the factory the XJ 1994 AW4 trans cooler is connected this way:

Supply oil line from trans (the front one on the trans) to upper port of OEM radiator > lower port of the OEM radiator to the return line of the trans (the rear one on the trans).

I read many write ups and im confused how to install the aux trans cooler :

1) trans > top of OEM rad > bottom of OEM rad > top of aux cooler > bottom of aux cooler > trans (thats the original settings for the factory trans cooler)

2) trans > top of OEM rad > bottom of OEM rad > bottom of aux cooler > top of aux cooler > trans

Which one is correct and how will it affect the AW4 temp if its installed one way or the other please.

Plus i want to install a temp gauge for the trans , the B&M comes with the complete kit but the oil line must be cut to install it, and the Jeep gauge brand (looks great its a jeep) from autometer comes with a sending unit and adapter to be installed on the trans oil pan.
which one is easier to install?

Thank you
 
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Either one will work.....

Just make sure you follow the flow directions for the cooler, as some may have a specific flow path, others, not so much (IE, inlet & outlet are marked on the cooler)
 
If you have a decent size aftermarket trans cooler, and you dont need the warm-up feature of the stock routing, ditch the trans cooler circuit in the radiator. It makes things much simpler and prevents the trans fluid heat transfering into the coolant.
 
xcm said:
If you have a decent size aftermarket trans cooler, and you dont need the warm-up feature of the stock routing, ditch the trans cooler circuit in the radiator. It makes things much simpler and prevents the trans fluid heat transfering into the coolant.
Click to expand...

I installed a Hayden cooler today, will ship a jeep brand trans and oil temp gauges from autometer with the pod but i need the T-Fitting full kit for the trans oil rail (like the kit that comes with B&M) , B&M doesn't sell it separate and couldnt find the kit online stores. Maybe you can help me finding a seller online for the kit i dont want to install the temp sensor at the trans oil pan.
 
The cooler is supposed to flow from the bottom up. It basically forces the fluid to stay in the cooler longer, thus cooling it further. Keeping the radiator tank inline with the cooler also helps the trans fluid reach operating temperature more quickly. This is especially important in cold climates. Also, if you bypass the radiator, your fluid could get really hot if you're not moving enough to have airflow through your aftermarket cooler. It's best to keep the radiator in the loop.
 
jeremyj said:
The cooler is supposed to flow from the bottom up. It basically forces the fluid to stay in the cooler longer, thus cooling it further. Keeping the radiator tank inline with the cooler also helps the trans fluid reach operating temperature more quickly. This is especially important in cold climates. Also, if you bypass the radiator, your fluid could get really hot if you're not moving enough to have airflow through your aftermarket cooler. It's best to keep the radiator in the loop.
Click to expand...

If you are moving too slow for airflow thru the cooler, then you are moving slow enough your engine temps are gonna be well over 200 Deg, as will your transmission if you have it running thru the radiator.

That's what the engine fan is for....to give you that air flow.

I do live in moderately cold climates, and I have always bypassed the radiator completely, and never had any heat related transmission issues.

You can do it either way....the bolded logic is flawed, but the underlined is true, if you need it due to the climate you are in.

Yes, if you direct flow from the bottom of the trans cooler, it will keep fluid in the cooler longer, but not enough to be of any substantial difference in how the cooler functions, and only the 1st time it is filled when the engine/trans is started and put into gear (like maybe a second longer at most). Doing that may help to keep air bubbles out of the cooler, and will ensure the tubes stay full, but that's about it. If the cooler is full of fluid as it should be, the direction of flow makes no significant difference.

The reason the stock radiator trans cooler fills from the bottom and comes out at the top is the colder water in the radiator is at the bottom, so the fluid cools off quicker if it is hot, but it will still be just as warm as the water temp in the radiator.

The only way to cool it off more is a separate cooler.


.
 
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My statement coincides with the vast majority consensus on plumbing a cooler. You can argue all you want, but it's true. Keeping it inline will warm the fluid faster, expand fluid capacity, and prevent the temps from going above engine temp. If it's left on its own circuit, without air moving through it, it could get even hotter. This all depends on your fan setup and surrounding climate as well. There are a lot of variables involved.
 
jeremyj said:
My statement coincides with the vast majority consensus on plumbing a cooler. You can argue all you want, but it's true. Keeping it inline will warm the fluid faster, expand fluid capacity, and prevent the temps from going above engine temp. If it's left on its own circuit, without air moving through it, it could get even hotter. This all depends on your fan setup and surrounding climate as well. There are a lot of variables involved.
Click to expand...

Your argument does coincide with the vast majority consensus of people living in colder climates. Living in warm/hot climates doesn't require any pre-heating of the transmission and plumbing inline will likely work against it when driving slowly, even with an electric fan. I think we can all agree on that.
 
SC driver, pretty hot here. I kept my radiator in the loop for the transmission. I bypassed it originally, and noticed that my transmission temp gauge I installed would fluctuate quite a bit. Out of curiosity I reinstalled the radiator into the circuit, and my temps are much more stable now. Temp climbs slower if I'm in traffic or sitting at a drive through. I know the great debate has pros and cons on both sides, but I do notice that having the radiator in the loop helps with temperature stability over the years I've had it installed. My cooler is also filled from bottom to top for what it's worth.
 
jeremyj said:
My statement coincides with the vast majority consensus on plumbing a cooler. You can argue all you want, but it's true. Keeping it inline will warm the fluid faster, expand fluid capacity, and prevent the temps from going above engine temp. If it's left on its own circuit, without air moving through it, it could get even hotter. This all depends on your fan setup and surrounding climate as well. There are a lot of variables involved.
Click to expand...

No arguing...simple scientific facts.

1) It will warm the fluid faster, true, if needed this is a good idea....if not, not so much

2) It WILL NOT expand fluid capacity...takes a bigger trans pan to do that. It WILL expand fluid volume...volume & capacity are not the same thing. Expanding volume is the opposite of what ya want to do. Warm fluid that has 'expanded it's volume' will now remove LESS heat from the transmission internals, and since it is thinner it will also provide less lubrication and not handle as much pressure

3) Unless you mount it in some weird out of the way place, it will have EXACTLY the same air flow thru it as the radiator...ya know that other cooler that keeps the engine from overheating. That's why there is a fan behind the radiator to provide airflow when moving slow. And since you always follow the 'vast majority consensus', you will mount it in front of the radiator, where the engine cooling fan will provide airflow thru it when moving slow just like it does the radiator

4) While in certain climates, it may keep the fluid from getting hotter then engine temps...it will also keep it from getting cooler then engine temps. In my vehicles, if I can keep the trans fluid below the 220 deg the engine runs at I will since trans fluid is best kept below 175 deg.....not so easy to do in a radiator cooler that at best drops it 20-25 deg.

5) Running the radiator cooler inline as you suggest MAY NOT keep it below engine temps, since the cooler is small and the time in it is short. If you have an internal issue in the trans or torque converter that is producing extra heat (like a slipping lock-up clutch), that cooler WILL NOT be enough to cool it down, and it will in fact heat up the engine if you let it go long enough. Been there - done that.

6) and for the statement about keeping the cooler full....trans fluid is a hydraulic fluid, and therefore not compressible...here's an example for ya:
Let's say the pump in my AW4 trans puts out 30 gpm flow rate, and my auxiliary cooler holds 1 gal.
Now, lets say I installed it right, the way you say I have to to keep the fluid in the cooler longer so it can cool more (in @ the bottom and out @ the top) & the cooler will stay full of fluid since it doesn't leak.
Now, when the transmission is in gear at lets say 50 mph, it puts out 30 gpm flow, which means the fluid will stay in the cooler 2 seconds (1 min / 30 gpm = 2 sec per gal).
So, please explain to me how the fluid direction will let it stay in the cooler longer ??? The ONLY way the time the fluid is in the cooler will change is if you change engine/trans speed/rpm.....direction of flow has no affect whatsoever


Now.....did you even read and think about my post ?? The only thing I said you had wrong was the claim that it helped keep the cooler full, and that it would overheat if moving slow, and I even explained why what you said was wrong. I also agreed with some of your statements.

Now about this general consensus....among whom ?? your friends ?? there is no right or wrong way to do it as long as it doesn't leak, and as I said, it is up to you to decide what you want and the climate you drive in. I personally, have seen more installed without using the radiator cooler than with, and I've seen quite a few installed (more than 2 dozen).


.
 
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Look, man. I don't have enough ****s to give about this to continue the argument against your "scientific facts". I did a ton of research before I plumbed my cooler and I was just stating the widely accepted, most common methods of doing so. Also, your argument for volume vs capacity is silly. Capacity refers to the amount of space that can be filled. Volume (in this case) refers to the amount of fluid in the space. Both are increased with the addition of a cooler. Not just one.
 
jeremyj said:
Look, man. I don't have enough ****s to give about this to continue the argument against your "scientific facts". I did a ton of research before I plumbed my cooler and I was just stating the widely accepted, most common methods of doing so. Also, your argument for volume vs capacity is silly. Capacity refers to the amount of space that can be filled. Volume (in this case) refers to the amount of fluid in the space. Both are increased with the addition of a cooler. Not just one.
Click to expand...

Whatever....you don't even know what you are saying. Yes, volume & capacity are increased with the addition of a cooler, but heat only increases volume, and that is what you said. Since I don't know you, and am not watching you say these things, I have but to take them at what you say.....and if what you say is wrong but you really meant something else, I can't tell. That's why saying it correctly is so important.

volume vs capacity. You used the words incorrectly, sorry. Capacity - 1) a 5 gal bucket has a capacity of 5 gals 2) volume - the volume that that 5 gals occupies may be more or less then the 5 gal bucket capacity depending on if it's boiling water or ice. You said heating the fluid up would increase the capacity...that is wrong. It increases the volume. You also said keeping the cooler inline would increase capacity. Putting a cooler in the system will increase the total system capacity, and bypassing the radiator will remove maybe 1/2 qt of that capacity.

Facts.....Hmmm.....they are what they are, you can like them or not, but they are still true.

'tons of research'.....not so sure here....All the info I put out I have personally seen or experienced, or is easily proven using science & common sense

Like I have said every time now, you can mount one however you want. Just because you, me, or anyone else thinks it should be done a certain way, doesn't make it right or wrong. Using provable facts can help, but it still doesn't matter in the long run unless you are in an extreme climate.

Considering the original posters climate, I'd say it'd be best for him to bypass the radiator cooler, and maybe even put in a remote mounted filter, as that will increase capacity by about another 1 1/2 qts to keep it cool as it's always pretty hot there (been over there, so I know).

I just don't like when people give misinformation out to people asking for help. And unfortunately, when corrected (or even questioned), those people get butt hurt.


.
 
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TRCM. Our climate is not extremely hot. We are in Lebanon, middle east not in the Gulf.
During spring and summer we have 20 to 32 degrees Celsius variable temp. 27 to 32 maximum and not more than a week or 2. During fall and winter we have 7 to 17 celcius, some rare days up to 23 24 and some days we even have below zero.

I Installed my aux cooler without removing the radiator one and on the electric fan side with a switch to the fan in case I'm on trail.
My coolant emp reach 100-110 maximum (gauge needle on the middle) before the e-fan activates and drop it to 70-80.
I installed a brand new radiator, new water pump and 180 thermostat with new housing, new water hoses woth 50/50 coolant and distilled water.

My question was how to plumb the hoses I was confused about which hose goes where (top or bottom for the return).
I ordered one gauge with 2 t-fittings and 2 sensors to monitor the Trans temp both ways. Will install those on a dpdt ON ON switch. Waiting for the shippement t arrive next week.
 
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It was hot when I was over there.......if you get down to freezing, then keeping the radiator cooler would be good.

It really doesn't matter if the inlet is on top or bottom.....I run them whichever way is easiest to keep the lines out of harms way.

Electric fan side ?? is that between the engine & radiator, or in front of the radiator. I don't remember where you said you put your electric fans when you installed them.

As long as you have airflow thru the cooler when the fan is on, you should be ok, but you also want air flow thru the cooler when the fan is off if you are moving.
 
TRCM said:
It was hot when I was over there.......if you get down to freezing, then keeping the radiator cooler would be good.

It really doesn't matter if the inlet is on top or bottom.....I run them whichever way is easiest to keep the lines out of harms way.

Electric fan side ?? is that between the engine & radiator, or in front of the radiator. I don't remember where you said you put your electric fans when you installed them.

As long as you have airflow thru the cooler when the fan is on, you should be ok, but you also want air flow thru the cooler when the fan is off if you are moving.
Click to expand...

Maybe you came July - August, that's when we have very hot days like today it's 32 here.

Installed infront of the radiator.
So it's aux cooler > rad (where the original transmission cooler is) > e-fan
 
yeah, is was the middle of summer when I was there

Ok, cooler location is good, just make sure it doesn't get clogged with bugs or mud & you'll be fine.
 
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