TRCM

Not all vehicles are the same I guess....but 225 deg on an 88 AW4 makes me wonder...........if your friend's vehicle is running 190 deg for transmission fluid temps AFTER going thru the stock heat exchanger AND an aftermarket cooler, he has a problem. Trans fluid should stay well below 200, and should be in the 150-170 range 90% of the time on a healthy transmission.

My 88 doesn't get anywhere near those temps, and it has 380k on it, the trans slips some under heavy load when 4wheeling, and it has never been rebuilt - only fluid/filter changes.

I've run an aftermarket cooler ONLY on cars and trucks, from 100 hp to 500+ hp, daily drivers to rock crawlers, stock and high rpm torque converters, and I have never had any over heating fluid problem, and never got close to 200 unless towing heavy.

Yes, liquid to liquid will always be more efficient, as the specific heat capacity of a fluid is greater than air.

And every OEM has that setup because every OEM designs the system to minimize wear by doing 2 things:
1) which means the trans fluid is heated up to normal operating temp as quickly as possible by using the coolant to minimize wear inside from fluid that is too cool which means the metal parts are too close together
2) also cools down trans fluid that is getting too hot (as in hotter than the coolant), but this time, it's to keep those metal parts from expanding to much and causing wear, which in turn heats the fluid up even more.



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Tbone289

The terms "cooler" or "heater" are more specific than "heat exchanger", because the use of those terms further illustrates which way the heat is normally travelling.


By following your logic, auto manufacturers should call the radiator heat exchanger a heater. The odd thing is, they call it a cooler. I guess Jeep just jumped on the bandwagon because all the other manufacturers were calling it that, even though it was wrong. The radiator manufacturers jumped the bandwagon too. It's a shame they can't call it what you say it really is--A HEATER.


As you say though, just because auto manufacturers and radiator manufacturers call it a cooler, that doesn't make it right. I guess I should be surprised that Jeep doesn't refer to the engine as a motor in the FSMs.

No, it isn't, and that is why it is referred to in all the FSMs as a COOLER.


They are not typically referred to as a heat exchanger or a heater. The temperature of the coolant in your radiator is not normally higher than the transmission fluid at operating temperature. And when I say operating, I mean under load. That picture I showed with the IR gun above is just after parking, immediately after a long highway trip through the hills. Humor us and show an example of how the radiator is heating the transmission fluid most of the time. I'm curious as to what coolant temperatures you think are present at the heat exchanger during the majority of normal operation, and the delta between the two fluids.

From the 2000 FSM:

TRCM

So, you quote a FSM, which is so right, it calls transmission fluid oil.

I am basing what I am saying on what I have personally seen when running the equipment being discussed.


Cooler means cooling per you, but it both heats and cools..............

Maybe you should call the heater core a cooler too, as it definitely cools the fluid......

Tbone289

Where did I say it only cools? Quote me. I've stated that it heats and cools, and that it's a heat exchanger over and over. You should probably go back and read.

It's called a cooler by auto and radiator manufacturers because that's its primary function. That is a fact, and that is what I stated. A heater core's primary purpose is not to cool, so people don't call it a cooler, but it does cool something as a result of being a heat exchanger, as all heat exchangers do. You should probably just continue to call all of these items heat exchangers since you seem to be confused as to their primary purpose. At least then you would never be wrong.

I might actually start to believe your claims if you could actually provide data that the primary function of the radiator heat exchanger, or cooler as so many manufacturers call them, is to heat transmission fluid.



Please share with us the details of your observations and how you came to the conclusion that the stock heat exchanger's primary purpose is to heat.


BTW, transmission fluid is oil based so yes, it is an oil. What kind of fluid do you think it is? LOL Base oils, viscosity index improvers, anti-foaming agents, additives, etc...a recipe very much like what we all call motor oil.

All heat exchangers transfer heat energy and, as a result, heat one medium and "cool" another. "Cool" meaning to remove heat energy.
A cooler is a heat exchanger, but a heat exchanger is not necessarily a cooler. Cooler is a term reserved for a heat exchanger thats primary purpose is to cool a medium, but it does heat a medium as well.
A heater is a heat exchanger, but a heat exchanger is not necessarily a heater. Heater is a term reserved for a heat exchanger thats primary purpose is to heat a medium, but it does cool a medium as well.
Oil is a fluid, but a fluid is not necessarily an oil.

on and on... See how that works?

TRCM

Transmission fluid is a hydraulic fluid, just like power steering fluid....based on oil, but much better at handling pressure and providing lubrication than at removing heat. That's also generally why they are designed to operate at lower temps before they break down.

Almost ALL hydraulic fluid is oil based...but they are still called and referred to as fluid, not oil. I only say almost because some of them today are synthetic and not oil based.

I do not have exact numbers to give you aside from what I already have....I don't record every thing I ever see for future reference (but sometimes wish I could have). I do remember when things are not as I expected (I use to think like you do).


So, you want to get technical over the term oil vs fluid, and insist on oil being the correct term since hydraulic fluid is based on oil, but yet you don't want to use the more technically correct term for a cooler or heater, which would be heat exchanger, as they are ALL heat exchangers ??

So, all oil/fluids are based on oil, so they should be called oils ??.

All heaters/coolers ARE (not just based on) heat exchangers, but they shouldn't be called such ??

You stated:
All heat exchangers transfer heat energy and, as a result, heat one medium and "cool" another. "Cool" meaning to remove heat energy. True, sort of....it's not 'heat energy' that is removed, it's simply energy, and using your terms, 'heating' something up adds energy, and cooling it down removes energy. Any heat exchanger removes energy from 1 or more fluids and transfers it to 1 or more other fluids.

A cooler is a heat exchanger, but a heat exchanger is not necessarily a cooler. Cooler is a term reserved for a heat exchanger thats primary purpose is to cool a medium, but it does heat a medium as well. Not true. Any cooler is still a heat exchanger, no matter what it's primary purpose is, as it still transfers energy between the 2 fluids. The colloquial term may be cooler, but that does not make it right.

A heater is a heat exchanger, but a heat exchanger is not necessarily a heater. Heater is a term reserved for a heat exchanger thats primary purpose is to heat a medium, but it does cool a medium as well. Not true. Again, any heater is still a heat exchanger, no matter what it's primary purpose is, as it still transfers energy between the 2 fluids. The colloquial term may be heater, but that does not make it right.

Oil is a fluid, but a fluid is not necessarily an oil. True, so why call a hydraulic fluid oil ?? Why does it say fluid on the bottle and not oil ??


There are heat exchangers whose primary purpose is to cool 1 fluid AND heat another, with both being of equal importance.

Any heat exchangers primary purpose is to exchange energy between 2 or more fluids. What side of that exchange we use, heat or cool, doesn't change the primary purpose, but generally, people call it based on what they think it does, ignoring that it actually does both.



Anyway, neither of us are wrong for the most part, but you are using generic terms, and I was being specific. I do not agree with all of what you say, and I also don't disagree with all of it, but that's life.

I put out my thoughts & experiences, and whomever is reading it can figure it out for themselves. I have never had any issues with running an aftermarket cooler by itself, nor have I had any issues running just the factory setup, as long as the transmission didn't have a mechanical problem.

Only problems I have had that are even related, were using the wrong type of hose (fuel vs hydraulic), and a leaking seal in the stock setup that put water in the transmission fluid, which gave me a lot of liquid soap to remove.

At any rate, I'm tired of typing for awhile............................. ........it's all good


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Tbone289

Jack oil isn't referred to as fluid, and it's hydraulic oil.

I couldn't care less what you call it. You are the one that started off denying it was a cooler, and it should be called a heat exchanger. As I've said over and over and over, "cooler" and "heat exchanger" are correct terms for the factory setup, because cooling is the primary function of that particular heat exchanger.

Remember when you said that near the beginning of the thread? This is where you started us down the road to semantics. Both coolers are heat exchangers, and it has nothing to do with whether they only heat, only cool, or do both.

Where the hell did you get that idea? I never said that. You seemed to think it was incorrect for the FSM to call automatic transmisson fluid oil, and seemed to imply that it was not a good source for information for anything because of that. I'm pointing out that it's not incorrect to call it oil. I never said that calling it fluid is incorrect.

And where the hell did you get that idea? I never said that. I will say it again, just to be clear: THEY ARE ALL HEAT EXCHANGERS. Why you could possibly think that I think otherwise at this point in our exchange is beyond me. Are you reading any of this?



Correct--heat is energy. Energy can take many forms, and this is energy in the form of heat, thus why I said "heat energy". However, incorrect--heat exchangers don't just transfer heat from one fluid to another. They transfer heat from one medium to another, whether that be air, fluid, etc. That is why the aux fluid-to-air cooler is also a heat exchanger, and the factory setup isn't exclusive in being one. Oh, and by the way, since you want to get technical, there really is no such thing as cooling. You can only add or transfer heat.

Quote:

Originally Posted by TRCM

A cooler is a heat exchanger, but a heat exchanger is not necessarily a cooler. Cooler is a term reserved for a heat exchanger thats primary purpose is to cool a medium, but it does heat a medium as well.

Right. I just said above that any cooler is a heat exchanger...so you actually should be agreeing with me and not saying I'm wrong. What I said is 100% true.

I'm just trying to define why we call some heat exchangers coolers and some heaters. And yes, what I said above is completely true about why we term them that way.

Quote:

Originally Posted by TRCM

A heater is a heat exchanger, but a heat exchanger is not necessarily a heater. Heater is a term reserved for a heat exchanger thats primary purpose is to heat a medium, but it does cool a medium as well.

Again, same as above. See at the beginning there where I state that heaters (meaning all heaters) are heat exchangers? What I said is 100% true.

Of course it is a heat exchanger, but if we call it a cooler, we know what its primary purpose is. Using the terms "cooler" and "heater" are more specific because they illustrate the purpose of a particular heat exchanger.

Quote:

Originally Posted by TRCM

Oil is a fluid, but a fluid is not necessarily an oil.

Great question. Let me know what you find out. Why is brake fluid not oil, since it's hydraulic fluid, and so is jack oil?

Agreed, but that is beyond the scope of this discussion.

A heater is designed for a specific purpose--to heat. A cooler is designed for a specific purpose--to cool. The purpose is specific. You can't reverse a heater and have an efficient cooler, and you cant reverse a cooler and have an efficient heater. So, yes, it does matter what side of that exchange we use. It is not based on what people think it does, it is based upon it PRIMARY PURPOSE.

Try heating your house in the winter by using window air conditioners turned around backwards, fan in reverse, so you're using the wrong side of the exchange. Let me know how that works for you.

No, I am using specific terms, and you are using generic ones. I am saying the factory heat exchanger is specifically a cooler, because that is its primary purpose. Once again, the terms "cooler" or "heater" are more specific than saying "heat exchanger" because the terms reveal the true purpose of the heat exchanger.

And one of us is indeed wrong--the one that is stating that the primary purpose of the factory heat exchanger is to heat the transmission fluid. The primary purpose is to cool the transmission fluid, and that is specifically why most manufacturers call it a cooler.

fb97xj1

I dont care what its called, or why its called that, as long as it does what its meant to.

Martlor13

you come into the shop where i work (tire shop that does some other repairs) and tell me you have a bad heat exchanger instead of transmission cooler, im not going to know what the heck you are talking about lol

5-Speed

You know, that tempts me to call up some place like Autozone and ask them for an engine coolant intercooler for a 99 XJ and see what they come up with haha.

Martlor13

I mean i know my way around vehicles decently, but i'm gonna be honest and say i have never hears of that term before lol

Doc5440