I recently purchased a new 2010 F-250, 5.4l, 4X4, 4:10, SB, CC. It also has a "towing package". It has the 5 speed auto which I believe is referred to as the "TorqShift".

I was nosing around and noticed that the trans cooler has hoses running to/from the radiator in addition to running to/from the transmission.

So I was wondering if there is additional cooling gained from the radiator before or after the fluid passes through the trans cooler itself?

Also, since I do tow a travel trailer with this truck (~6,500 lb) through the hills of western PA, does anyone have experience as to how effective this trans cooler config is on my truck?

Thanks,

 

Traditionally, most automatic transmissions were cooled by a coil in the cold side of the radiator. It looks like Ford installs an additional loop of finned tubing, usually around the bumper, for additional air cooling with the towing package. To be most effective, it should be installed ahead of the loop in the radiator, so I hope they get that right.

I have an Aerostar with the dual ATF coolers, and the experience of most Aerostar users is that the combination is not sufficient for anyone doing any real towing. We usually end up replacing the loop of finned tube with a large plate type cooler. Since the space between the grille and AC condenser is quite tight, we usually remove the loop for the power steering cooler to make space. In most cases, we also re-routed the PS fluid through the finned tube loop of the stock ATF air cooler (in the bumper).

 

Don't know your model year, but in general, most automatic trannies have an in radiator cooler. Heavier duty applications also have a finned cooler outside of the radiator.

On my 94 F250 the auxilliary cooler is about 12X6X2 and is made up of staked plates, kind of looks like a honey comb. It sits in front of the radiator and has hoses into the radiator cooler and from the tranny. I use this rig to tow an 8000# trailer thru the teens up to well past 105 degrees and in good hills like Californias grapevine and Oregons blue mountains. My temp rarely goes past 200/210 unless I am in a head wind or stopped or driving in reverse after a long hot drive. So my opinion is the combination of coolers is adequate for what I do. I would assume that was Ford enginnering's opinion too when they designed the system.

The in radiator cooler has two functions. To cool AND heat. Cool during warm weather and normal use. And to heat when it is cold. It takes a surprising amount of time to warm up fluid to more than 150 degrees in cold weather, several hours in my experience without a tow, freeway driving in below freezing temps. The guage which starts at 100 doesn't even bump for maybe an hour on cold days.

Good Luck,

Jim Henderson

 

There is A LOT of cooling to be gained by the radiator cooler. It is extremely effective at removing heat from the ATF.

The right way to route the fluid is from the transmission to the radiator where most of the heat is removed, then to the air to oil cooler where it can further lower the temperature. That's the way Ford did it.

If you go to the air to oil cooler you won't get the trans fluid as cool when everything is hot. In hot ambients when the truck is working hard the cold tank on the radiator can get quite warm. The radiator cooler can't cool below this temperature, but the air to oil cooler always cools nearer to ambient temperature.

The cooler on a 6.0L truck is not a loop with fins. It is a large stacked plate cooler.

There is only one function for the transmission cooler in the radiator. It cools the ATF. I have tested cars and trucks with radiator coolers as cold as -40°F and NEVER found any condition where the coolant around the transmission radiator cooler was as warm as the ATF.

When the engine is started after the car/truck sits all night everything in the radiator is the same temperature. The ATF going into the radiator warms up quicker than the coolant around the cooler. As long as the engine's thermostat is closed the flow into the radiator is essentially zero. The radiator is VERY effective at these cold temperatures. This means the cold water sitting around the trans cooler is still at outside temperature.

Once the engine warms up the thermostat opens and ~200°F coolant goes into the radiator. At the same time ambient temperature coolant (-40°F) is taken into the engine at the lower hose. That cools the engine quickly and the thermostat closes again. Flow in the radiator stops and the coolant in the radiator quickly gets close to ambient again. Hot coolant doesn't make it to the cold tank where the trans cooler is located, so that cooler always has coolant that is nearly outside temperature.

None of this is what I think happens. Cooling the transmission was my job at Ford for three years. I spent way too much time in cold weather places and cold wind tunnels measuring all of this.

 

Very informative information. Thank you all.

Mark K, so am I to understand that in your experience and expertise you would consider the cooling config in my truck (2010, F-250, TorqShift, 4:11, stock aux trans air to oil cooler, etc) to be sufficient and effective for the towing I'm doing (6,500 lb travel trailer)? I've read your responses for some time and respect your opinion.

Thanks,

 

That's a good way to overheat the engine.
The circuit to be cooled should go transmission-cooler-radiator and back to the transmission. You need to shed heat or else you're dumping it back into the engine, and yes the radiator cooler does help to regulate the transmission warmup. The coolant in the radiator isn't wildly changing temperature, it is still quite warm when it goes back into the engine, typically well over 100degrees.

 

Yes, it will be fine. The cooling on your truck is excellent.

Have you ever measured any of this? I've run cars and trucks with 30-100 thermocouples throughout the cooling system to determine how all of this works.

How does the radiator cooler help regulate the trans temperature during warmup? When I measured the temperature the coolant around the cooler (ever measure the coolant temperature around the cooler? It's not easy to get a thermocouple in there) the coolant was ALWAYS colder than the ATF. From what I remember of my college and graduate school heat transfer classes, and from working with heat transfer for 30 years after college, you can't warm the ATF if the coolant is at a lower temperature than the ATF. The ATF is actually warming the coolant.

All the OEMs that have both coolers run it from the trans to the radiator cooler, then to the aux cooler, and then back to the trans. Are you saying you have better test data than ALL the OEMs and you have found that we all do it backwards?

And yes, the trans does dump heat into the radiator. So does the aux cooler if it is in front of the radiator. The engine cooling system is designed with that knowledge so that it has enough capacity to cool.

When we engineered these trucks we didn't just think about how it works, there are long and hard calculations performed, computer modeling, and a lot of testing. It is a complicated system.

 

"the coolant was ALWAYS colder than the ATF."

Odd, I must have an inaccurate set of guages, or as the other guy said, the cool tank is much cooler than the hot one. My engine coolant got warm MUCH faster than the ATF temp guage showed. It sometimes took a couple hours for my ATF guage to get anywhere near to what I would estimate was 150+. I assume the engine coolant was around 190 since that is what the thermostat was rated at and the engine temp guage usually runs around the O and R of Normal in cold weather, and that usually only took me maybe 2 or 3 miles at freeway speed in freezing weather to get to "normal".

But since the engine temp guage takes a reading outside of the radiator, the coolant in the cool tank could well be much lower than the guage indicates. The Autometer guage for the ATF only has indications for 100, 180 220 and 300 and not evenly spaced at all. It appears to be nonlinear so readings between tick marks are highly speculative, so who knows what temp my ATF really is while taking time to get up to operating temp. Also the sender for the atf temp is on the outlet of all the coolers, so it has been cooled. In retrospect that may be the reason I "Think" the ATF is so cold, becasue is has been cooled.

I would take the word of the tranny engineer or a tranny shop over what my eyeball tells me, but it sure seems like the ATF is cool for a loooong time when ambient is around freezing.

just a shade tree mechanic observation,

Jim Henderson

 

Jim,

You're right, the ATF is cool for a very long time longer than the engine coolant in cold ambients when you are measuring the coolant temperature before the radiator. In freezing ambients the coolant temperature can drop 100°F across the radiator. Where does that leave the cold tank coolant temperature? In ambients below 0°F I've seen more than 150°F drop in coolant temperature across the radiator.

 

Thanks to Mark for the excellent detailed explanations. You're able to do the types of measurements most of us can not.

Having lived in Detroit, I understand that in cold weather the cold side of the radiator can drop over 100F from the hot side, so cooling the ATF there is not an issue. In fact, you see a lot of trucks using zippered covers in front of their grilles to reduce the amount of cooling on really cold days.

But what about in hotter climates, where you are challenged to keep the engine cool? If you had two coolers, one outside of the radiator, and one in the cold side, ATF entering the internal cooler first would release most of its heat there, which would go directly back into the engine with no other forms of cooling.

Would it be better to use the external air cooler first, where the biggest temperature differences causes the greatest amount of heat transfer? Yes, I realize this heat then goes to the AC condenser and radiator, but there the transfer would not be as efficient as being carried by the liquid coolant directly back into the engine. In addition, if you place the external air cooler in front of the hot half of the radiator, the liquid coolant still gets cooled by flowing through the cool half of the radiator. Now the ATF entering the radiator cooler contains much less heat, and will therefore send less heat back into the engine. Just theorizing here.

 

No, it doesn't work like that. You get the most trans cooling efficiency by having the greatest delta temp between the ATF and the coolant. Dumping the heat into the radiator from the ATF directly to the coolant or the ATF to air to the coolant doesn't really matter. Either way adds just about the same amount of heat to the engine.

 

Just thought I'd update on some transmission fluid (and engine coolant) temperatures I experienced over this past weekend.

I purchased a ScanGauge II a week or so ago and connected it to my OBD port for this weekends trip. We pull a camper in the 6,500 lb range. This weekend we went to a campground at Raystown Lake and had to deal with two 10% grades that lasted about 2-3 miles (these grades are posted on state highway signs, not guestimated). In addition, the ambient air temps were ~92 degrees F and very high humidity. It was hot!!

Pulling the 10% grades the trans fluid temp got as high as 194 F when I had to slow down for a slower truck-travel trailer, and the engine coolant temp got as high as 206 F. When I was able to pull the two hills at my speed, the trans fluid temp ran around 183 F. Most of the rest of the trip (~65 miles) the trans fluid temp ran between 170 and 180 F and the engine coolant around ~ 190 to 195 F (all while pulling the normal hills of western PA, but not all 10% grades! ).

Overall, I'm very happy with how this truck performs pulling our camper. I thought the temperatures I was seeing were appropriate and "normal". And I thought it was fun, interesting and informative to watch the ScanGauge. As a side note, the dash needle gages always were dead-center in the middle of normal throughout all this.

Just thought I'd share some first hand experience.

 

Thanks for the great conversation and expertise. What is the best way to determine the actual flow of the fluid to add another (yes 3rd) cooler? I monitor my temps regularly, and when pulling a heavy load, it is clear that the engine temp gets hot and causes the trans temp to elevate. (sometimes even without pulling, the engine temp can go over 200 and then the trans temp starts to climb. The stock gauges on the dash are always in the center, while the engine temp can range from 180-220, and the trans temp can go from 150 to 185. I want to add an additional cooler for the trans after the radiator to pull a little extra heat out, while adding an aux electric fan in front of all of it.