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So i'm putting in my tranny cooler, and I was told by my mentor/ tranny builder to go inline with the factory "cooler" , and Ron Sessions, here's the question should I run it on the feed or return. If I run on the feed, it will cool then get heated by the coolant and return to the tranny. On the return it will go through the radiator and get warmed then cooled and back. Whats your guys opinions?
 

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Well, you've just opened up a can of worms, as there are 2 distinct thoughts on this. ;)

First thought: Keep the tranny fluid as cool as possible at all times - that means don't even hook it to the radiator. Thought here is that instead of cooling the fluid, it will heat the fluid. If you go this route, do the external cooler last so it cools the fluid further.

Second thought: The radiator will maintain more consistent temps than without, and will cool the fluid first before the external cooler. Personally, this is the way I do it. Using the radiator is also a good idea if you drive your car in cold weather, which is generally not a concern for most of us.

Best bet is for you to install a temp gauge and see where you are at, and go based on the readings. I've read that the tranny fluid should be kept cool, and the cooler the better - which really means avoid the radiator if your fluid stays below 180° to start with.
 

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anther thing to consider is what quailty of cooler are you planning to install .......

there are the cheap three pass bent tube with fin's type .... (cheap)

then there are the multi-stack plate coolers most of which are VERY high Quility ... an come in all size's & fittings you could possibly ever need .......

IMO buy a quailty cooler & mount it correctly & your trans will live a LONG happy life :D

I myself use one of the Multi-stack plate coolers made by Sertab & run it alone without including the radiator cooling tank at all .......

but I'm in Ca an it doesn't get cold here :D even with a mild stall converter Pulling the boat across the desert !!!

the cooler has never gotten to hot to lay my bare hand on :)
 

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Just a couple of things to ponder.

1. Has it ever occurred to you that there is a pre-determined optimum fluid temperature or at least a point that it is considered excessive. Factory engineering is obviously of the opinion that temperatures in the return tank (lower hose) of the radiator are effectively lower than that of "HOT" tranny fluid or it wouldn't be identified as a "COOLER".

2. Routing hot transmission fluid through a remote cooler FIRST, may actually be to your advantage, as the coolant in the radiator would be disipating heat rather than conducting heat.

This is coming from personal sense and sensibility. If something scientific trumps this line of thought, I'd be eager to hear it.
 

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Bypassing the radiator, and using only an auxilliary cooler will allow your trans to run its coolest. The radiator "cooler" only adds heat to the fluid.
 

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Bypassing the radiator, and using only an auxilliary cooler will allow your trans to run its coolest. The radiator "cooler" only adds heat to the fluid.
That's not necessarily true, it takes a heck of a lot more than 200* to burn tranny fluid and burnt fluid is what is trying to be avoided. It's far more likely for summer temps, towing and running up against the stall to overwhelm the capabilities of the factory (rad) cooler, that hardly translates to "adding" heat to the fluid, quite the opposite, in fact. An external cooler is needed for systems seeing temps well in excess of that in the radiator.

When an engine mounted temp guage reads 220, the coolant temp in the return tank (already passed thru the radiator) is going to be considerably cooler, therefore, cooling the fluid. If your returning coolant is much, if any, over 200*, than Your going to have more immediate problems than tranny issues.
 

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FWIW my feeling is that the line going through the rad. will lower the trans fluid temp Esp. behind a high hp eng and high stall converter and then will be cooled more with the external cooler. I would get as big a cooler in front of the rad as you can. One experience I have is that with a loose converter and no external cooler a car that runs cool normaly travels up a long low grade hill the eng temp goes over 220. The trans is adding more heat to the rad. if it went back to the trans at a cooler temp all would have been better.
 

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My trans never goes over 150 with the radiator bypassed, and run through a stacked plate cooler. How is it going to be more efficient in removing heat by first running it through a radiator that is at 200 degrees? It won't.
 

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My trans never goes over 150 with the radiator bypassed, and run through a stacked plate cooler. How is it going to be more efficient in removing heat by first running it through a radiator that is at 200 degrees? It won't.
But how hot is it entering your cooler?
 

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The inlet line is slightly warmer than the outlet. The pan is a nice comfortable warm that I can keep my hand on. When I used to run the radiator "cooler" only, the trans pan would get scalding hot to where if you brushed against it, you would get burned. I didn't have a gauge for the trans then, but scalding hot vs. warm is a huge difference.

The 150 temp is after several passes at the dragstrip. The trans normally runs 120 degrees. B/M stacked plate.
 

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First of all, the coolant in the return side of the radiator is cooler than whatever the guage indicates, simply because it has already travelled through the radiator. As a matter of fact, it will argueably be the lowest temp in the entire system. To the point of being able to absorb the heat of the engines operation and still only be the figure that you are seeing on the guage.

As for the fluid temp, it depends where the sensor is located. Taken from the main line port of a TH400, I'd say that is a fair example. Other trannies offer less accurate alternatives and a T'd cooler line would be totally moot.

It could be that 2525 is in the middle of an ice age or something. Good to know that Global Warming of the 21st century is a temporary thing. BUT, I can tell you this, in Vegas, on any given August afternoon, the water in my dog dish can exceed 120*. Put the bowl in direct sunlight and you can poach an egg.

Considering that the factory has to engineer the system to accommodate any number of climates and driving conditions, I'm gonna have to stick to my guns here. Any temperatures reached in the radiator aren't going to be detrimental to the fluids service limits. Excessive trans temps beyond the cooling capacity of the radiator necessitate remote coolers.
 

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Yup, can of worms, discussed her many times.

I do what Rowdy does. Aux cooler first, dump as much heat as you can, then trough the OEM cooler and moderate the temp close to where the engine temp is.
 

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Some people just won't accept real life expeience, and choose to cling to whatever they have heard previously in life. There is no way the coolant on the return side of my radiator is less than 150 degrees. What does your trans temp gauge read?
 

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ok ....... I'll try to explain this anther way .. I'm sure you all know that cars are built by "bean counters" you know the funny little guys with pocket protectors & thick glass's who's whole reason in life it to CUT the price on any & every thing they possibly can !!
if you notice Heavy duty service vehicles all get OIL-Trans-power steering COOLERS !!!

you won't find these items on your run of the mill passenger car becouse it would add to the cost & make it last longer ... ( p.s. bean counters like things to wear out !)

so what way save's the most money & sells the most units !! Cooler or NO Cooler/ I.E. in the radiator ??
Up till the last time MY computer crashed I had a really cool chart telling the life span of a transmission by the temps it experenced .... & the 30 or so degrees that taking it out of the radiator & running just a GOOD multi-plate stacked cooler is a much better way to go ......... as long as your not driving across the NORTH POLE !!
 

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I am a supervisor at a nuclear power plant and watch all types of gauges and meters all day. I have had it engrained in my head to always believe your indications. With that said, the only real way to see which line up is best is to install a tranny fluid temp gauge and run different cooler line ups and see which one works best. Real data does not lie.
 

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Some people just won't accept real life expeience, and choose to cling to whatever they have heard previously in life. There is no way the coolant on the return side of my radiator is less than 150 degrees. What does your trans temp gauge read?
Some people just don't have REAL LIFE EXPERIENCES and choose to cling to whatever they have learned in their personal, minimal and sheltered enviroment.

I wholeheartedly believe that an external cooler is superior to a radiator incorporated unit. Never said that I didn't. Heck, I have one on everything that I own. Five, of which, came from the factory that way (4 Class A Motorhomes, 1 F350 4X4 4dr longbed).

The point trying to be expressed was that the fluid will maintain it's integrity up to and above 200*. Although, I've never previously connected the two, there is probably a secondary engineering aspect associated with the routing of the fluid (that, yes, under normal conditions is often times lower in temp than the coolant) and I'm going out on a limb here, because this is not a factor that I have ever heard specifically addressed.

Similarly to an engines crankcase (admittedly to a lesser extent), there is likely a certain advantage to bringing the fluid up to operating temperature, simply in avoidance of the accummulation of condensation. Like mentioned in an earlier post, there is no doubt a temp range that is considered optimal. I would venture to say, and again, this is only speculation on my part, that temp would effectively burn off contaminants (evaporate moisture). yet avoid damaging the molecular structure of the fluid.

This is a personal revelation that came as I typed. It may never have been a consideration in the engineering, but could be argued as having at least a trace of merit. More than anything, it is meant to thwart the universal application of the "my experience" is fact statements. The original poster did solicit advice and personal experience in this matter and if it were me, I would welcome all responses. In my case, I included the arguement commonly expressed when choosing one of at least three methods used when incorporating an external/remote cooler. Whether it is the decided method does not matter to me and very well, may not be ideal for their circumstances. That, by no means, is a condemnation of the advice of another, rather an opinion based on more than just laying my arm across the transmission pan. Just F'n with you Wooderson, couldn't resist poking a little fun at ya :D

From my own experience, when working in your driveway in July, don't pick up a wrench left in the direct sunlight. Not bare handed anyway.
 

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you point is valid ......... but I don't know anyone willing to put in all the gauges necessary to monitor every thing happening under the hood ...
lets see....... oil pressure . oil temp . before & after cooler. oil pressure after cooler.... trans temp at pan . trans temp at cooler .. trans temp after cooler. water temp left head . water temp right head . water temp intake. water temp lower rad. water temp upper rad . fuel pressure at electric pump at tank & fuel temp. fuel presure at carb inlet after fuel filter & fuel temp after filters. lets see .... oh its EFI so we need Inlet temp & engine temp & Map..... oh lets not forget the normal stuff like Alt & tack & fuel guage ........ OMG where the people going to sit !!!
 

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The best way to convince those of you who don't believe the same as myself is to hook up a temp gauge for the trans. Then you will be able to see what I'm talking about. Everyone have a good weekend. :)
 

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I use a stack plate cooler that bypasses the radiator in my supercharged 01 chevy truck, runs 125-150 on hot days and never exceeds 180 when towing.
 

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One other thing to mention is that a transmission won't produce condensation inside by running it cold. There is no combustion taking place as in an engine, and so no water as a by-product.
 
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