Good morning all, I have a 1980 F350 DRW that I am working on. RWD, C6, 4.10 axle, 400 that is currently at the machine shop. I have the trans out and I will be replacing the filter and will go ahead and install a Transgo SK-6 kit. I have never really driven the truck, it developed a huge rear main seal leak shortly after I got it.
The question is if I put a larger trans cooler in front of the radiator can I eliminate using the trans cooler in the radiator? From what I have read water kills transmissions and radiator coolers are know to leak coolant into trans cooler portion. Truck will not see a ton of miles, some towing and hauling when it does get driven. Thanks for any feedback.

 

Your observations are correct. The Caterpillar equipment I worked on had separate coolers for engine oil, transmission and water. Eliminate the possibility of cross contamination.

Hobo

 

I've never heard of running an air-ATF transmission cooler vs a coolant-ATF transmission cooler due to the threat of failure. I could see it in industrial equipment like Hobo mentioned, but coolant-ATF coolers aren't only used in heavy duty trucks. Pretty much any modern automatic transmission vehicle uses coolant-ATF transmission coolers. To each his own though.

 

Normally the aux coolers are in front of the coolant radiator,flow wise. My thought was that will keep the trans fluid at a steady level not too cold, not too hot. The only problem I could see with running a dry cooler is that the temp is not really regulated. If you drive in colder weather the trans fluid might get cold.
Someone else will need to chime in if that is a serious concern or if it doesn't matter.

 

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I agree with your logic.... I'm running a couple of factory setups with the combination all in one. On the other hand, I have added extra (stand alone coolers). Some depends on the environment. Some depends on a man's previous experiences... For some, it's like buying insurance... We pay for it for the peace of mind and pray we don't need it.

@BlueWhiteFord
Makes a good point about ambient temp..... Too cold was never an issue in Louisiana... Now, in Montana that is a possibility... May have to run a radiator blanket here.


Hobo

 

Definitely run your trans coolers through the radiator trans coolers and then to your auxiliary trans cooler.
the transmission oil needs to come up to temperature and it does that through the radiator trans coolers, it needs its temperature limited and that is where the auxiliary cooler comes in.
you would like the temperature of your trans fluid in a window aprox 120-170 °f

 

Now you have made me unsure
I gonna take a look tomorrow to see how it is set up from the factory. I have a factory aux trans cooler and could have sworn it went through the aux first, but now I am not so certain anymore. Your logic makes sense too.

 

I only bring this up because I was watching Precision Transmission channel on YouTube and he was showing some trans that had cooler failure at radiator that caused complete trans failure. I live north of Seattle where temp are not very extreme, hot or cold.

 

Hey, I watch him too, great channel even if a lot of it is Cheby work. He makes it look SO Easy lol....

 

If you buy the cooler and read the instructions, they say always use the factory radiator cooler AND the aux cooler with it. They claim the auxilary cooler you are buying is just that, a aux cooler that adds to the cooling of the factory system. If you eliminate the factory cooler you will have to run a very large separate cooler.

 

I'm sure. It goes through the radiator cooler first, then the aux cooler.

 

most comments here are accurate. the bigger issue is routing. failure of components is a given of when, not if. its just part of owning equipment. properly built and maintained equipment should last its engineered lifetime. many and most catastropohic failures are a result of neglecting-ignoring these factors; maintnance testing and component life.
Your engine coolant temps should regulate both your trans temp and your engine oil temp. lubricants first task is cooling, then in the case of an automatic its fluid dynamics. Engine coolant should have the task of regulating the other lubricants temperatures.

this means the transmission fluid must go through the coolant to index its own temps in relation to what the coolant is registering as engine heat.
ATF in an automobile should be at its lowest operating temp 175. its extreme hottest should not exceed 215 in farenheit.
this is ideal but not always possible. So the engine cooling system is old or poor maintenance the radiator is blocked with crud or multiple layers of coolers. the fan is inadequate, all contribute to poor coolant performance. thus poor regulation of other fluids relying on engine coolant as their index.

for cold warm up the radiator heat exchanger is indespensible to get the trans fluid to working temp as rapidly as possible , and to hold it there during operation.

the very best way to approach this issue in a heavy truck with a transmission like the c6 is to , if possible leave it as factory and be sure every component is in top repair. if you find that you are burning fluid and the cooling system is perfect, then you go the next step because the radiator is not keeping up and you are using the truck beyond design parameters , or the factory missed the target in design


the routing is important and by my logic, the trans fluid coming off the hot side should go to the auxillary cooler first, then to the heat exchanger in the radiator tank next,. in this way the coolant has the last say in trans fluid temps.so that it is indexed to engine cooling temperature. the other way round you have no control of the exiting ATF fluid temps coming from the flat plate cooler and going directly to the transmission.

the flat plate cooler in front of (or preferrably to the side of ) the radiator, will take the spikes out of the heated fluid ( sometimes as much as 30* by my research), thusly reducing the load on the cooling system and offering a more stable fluid temp introduced into the radiator heat exchanger as it begins its return trip to the trans pan.
likewise when very cold, the trans will heat rapidly due to the friction of the torque converter. this will get hot faster than the engine coolant, but only slightly. this temp flows through the auxillary generally when the vehicle is in warm up and then aids the coolant to reach temp as it passes back through the radiator. this action is less remarkable in effect.

 

Have you measured this, or just done a thought experiment? A thought experiment is where you just think through what will happen without testing it. When I was an automatic transmission cooling engineer I tested this extensively. THE RADIATOR *COOLER* NEVER WARMS THE ATF. The colder the ambient air the more the radiator *COOLER* cools the ATF. It never, ever, ever warms the ATF.
The radiator *COOLER* is in the side of the radiator where the engine coolant has already been cooled. At very low temps the engine thermostat only opens for a very short time. Hot coolant is sent to the radiator in spurts. The coolant spends a lot of time sitting in the radiator where it is cooled to near ambient temperatures. Then this near ambient coolant hits the trans cooler. How can coolant at or below 0°F heat the ATF? It can't happen.

Wrong. This shows a lack of understanding how the ATF is cooled. See above.

This is just plain wrong.

 

I am just going by my experience. I had a 1980 f150 in good mechanical condition, completely stock with a c6. Ran fine for years, then I borrowed a trailer to tow some vehicles. Everything went fine, but I noticed a couple of weeks later the transmission was acting differently. Hesitation to drop into gear, and other little odd things. I checked the fluid and it was very dark and smelled burnt. I changed the fluid and all the little symptoms went away and it drove like new. I hadn't changed the fluid for years, so I figured it was old and needed it.

Fast forward several years later and I was moving and used the car trailer again. Afterward, same thing happened and the fluid was very dark and stinky again. Changed it again and this time I added a small cooler in series with the radiator cooler. Everything was fine again, it must be hard to kill one of these c6 transmissions. Afterward, I towed the trailer some more, and never had any more problems with it burning the fluid.

When I installed the cooler I followed the instructions that came with the cooler. There is a certain way they want it hooked up. They tell you in the morning when everything is cold, before you do anything start the engine and run it in park for just a few seconds and then turn it off. Then feel both of the transmission lines, one will be warm. It's amazing to me that just idling it for that very short time warms the fluid in the one line that quick, it's very noticeable when you put your hand on it. Once you found the warm line, they wanted that hooked up a certain way, I can't remember how it went exactly. But there is a certain order they want the cooler inserted into the factory loop.

 

Here's some instructions for a larger fancier cooler than I used. It is larger and has it's own fan. Looks like it can be hooked up stand alone or in series. And it looks like they want the hot line from the transmission going to the factory cooler first, and then the aux cooler is located downstream of the factory cooler. I personally would always use the factory cooler along with the aux cooler, unless you were in a situation where you did not have a factory cooler, for instance in a old classic car or truck that did not come with a radiator cooler.

https://www.google.com/url?sa=t&rct=...OWsEcLKQf-Znyg