About Transmission cooler and radiator

[Justin J]

Your reply is Very informative, CWD! Thank you!

 

[Littleant]

Auto manufactures have been running automatic transmission lines through part of radiators for decades. I don't really see the issue as it heats the trans fluid up quickly in extreme cold, prolonging the life of the transmission, and keeps it cooler on hot days, also prolonging the life of the transmission. My 2008 Silverado has the same set up, so does my 2005 Workhorse W22 RV chassis with an Allison 3000 trans.

I chose to bypass the radiator on my trail rig because when crawling (going slow for miles) the trans fluid temps were pushing up the coolant temps, and the coolant temps were pushing up the trans fluid temps. You could watch one start to rise in temp, then the other, then the other, etc.. I also have 2 trans coolers and an electric fan on the big one, and a all-aluminum radiator.

BKennedy is correct. Coolers have been Integrated for decades. Never seen one fail during the 60's-70's when I did auto repairs. Radiator and coolers were copper

 

[Bettywhite]

Is it true that Ford combines the transmission cooler into the engine (coolant) radiator? And the two different fluids can potentially mix together when there’s a leak?

If yes, has anyone installed a STANDALONE transmission cooler for the truck? Thanks!

Yes I disconnected my trans from the radiator and installed a separate trans cooler so my trans temp could stay cooler when out rock crawling

 

[Len Thornton]

Is it true that Ford combines the transmission cooler into the engine (coolant) radiator? And the two different fluids can potentially mix together when there’s a leak?

If yes, has anyone installed a STANDALONE transmission cooler for the truck? Thanks!

They do, indeed! Not uncommon in older domestic vehicles, but a recipe for disaster. I had my radiator go on my 2007 Explorer in 2019. Bought a replacement one from Autozone - made by Spectra. Went in no problem, after following a YouTube for the easiest path. Had problems a few days later. Coolant was brown and foamy. Did some research, and it was indeed tranny fluid leaking into the coolant. The bigger issue was coolant leaking into the transmission. Automatic transmission clutches don't like water - at all! Replaced the radiator and drained and replaced my tranny fluid, but the damage was done. Put in a claim for a remanufactured transmission with the Autozone regional manager. He stalled for a week and then said their liability does not not extend to other parts - they only replace the bad radiator. Now, I've worked in auto parts stores way back in my college days. I know the parts vendors allocate a certain amount of cash for claims like this. But, generally not for do-it-yourselfers. A commercial account getting a bad radiator would be taken care of, as he represents a fair amount of future business. End result - I'm out $3,000 for a new transmission. But, I'll never set foot in an Autozone again, and I tell everyone I meet my story. FWIW, a standalone transmission cooler is a great idea, especially if ever towing.

 

[keptman]

Is it true that Ford combines the transmission cooler into the engine (coolant) radiator? And the two different fluids can potentially mix together when there’s a leak?

If yes, has anyone installed a STANDALONE transmission cooler for the truck? Thanks!

There isn't a car out there with a automatic transmission that doesn't have this type of setup. In all my years of working on equipment and cars. Ive never seen a failure of the oil into the radiator system. Radiators tend to fail elsewhere.

If your that concerned about it. Whatever after market cooler you use go bigger then you think you need if your going to remove the system in the Radiator. A lot of aftermarket units account for the displacement of the stock unit plus the one your looking at.
If you tow anything go big. Never hurts to keep trans cool.

 

[1Neptune]

All automatic transmission cars have that feature. Tranny fluid runs through the radiator. Been doing that since the 1950's

 

[spt87]

Thanks! My 06 4.0SOHC Explorer has 5R55S, I think.

What a stupid design to combine the two coolers in such a way! At least don’t let them mix fluid when one is leaking!

“Smart” engineers! DESIGNED TO FAIL BIG!

This is nothing new. Every car or truck with an automatic transmission I’ve ever owned (or seen) is set up like this - going back to the 1970’s (domestic or foreign). I also think it is very rare for a type of failure where the two fluids mix together. I’ve never seen or heard of it. I’m sure it has happened but I personally don’t worry about (never even considered it until reading this thread). Change the antifreeze regularly to keep the corrosion protection additives fresh - use distilled water to prevent mineral build up in the cooling system and many more common problems will be taken care of along with reducing any small risk of the transmission heat exchanger in the radiator failing.

 

[Larry Compton]

My concern is a cooler leak could mess up transmission, letting alone the fluids themselves.

The design to warmup transmission fluid is almost meaningless.

One thing I want to say is, based on my research on this, almost all cars with an automatic transmission have a cooler/radiator like this, not just Ford! To name one, Toyota 4Runner has this stupid design too!

This has been done for more years than most of you have been alive. Physical contact is a better way to cool the fluid than airflow especially if the car isn't moving fast enough. The transmission builds heat especially if it isn't in 1 to 1 gear ratio. That is in slow moving and especially if you are stuck in snow or mud.

 

[Berepair]

Replaced a radiator last week that was over filling with ATF. 99 Chevy Tahoe.

Happens, but rare.

Just sayin'

 

[pelagic1122]

Is it true that Ford combines the transmission cooler into the engine (coolant) radiator? And the two different fluids can potentially mix together when there’s a leak?

If yes, has anyone installed a STANDALONE transmission cooler for the truck? Thanks!

A transmission cooler has been incorporated in the radiator on pretty much every automatic transmission car/light truck for as long as I can remember. Even if you get the optional tow package with an external cooler you will still get the default cooler in the radiator that everyone gets. This is not a new thing and is not unusual to the Explorer. Can it cause a problem? Sure - things happen. But considering the number of vehicles that have that setup the failure rate is pretty low.

Yep, virtually every vehicle is this way.

 

[94Eddie]

As a heads up, the 6R60/80 transmissions, and others, have an internal flow value and will not circulate fluid to anything outside the transmission unless it is at full operating temperature. This nullifies external cooling measures getting the fluid temps lower than the target temperature set by Ford. This is also why flushing these transmissions isn't possible if the fluid temperature isn't at the proper level. So installing a cooler on some transmissions will help lower fluid temps in severe duty conditions but they won't drop the temperature below what is targeted by the programming.

 

[CRowlett]

Is it true that Ford combines the transmission cooler into the engine (coolant) radiator? And the two different fluids can potentially mix together when there’s a leak?

If yes, has anyone installed a STANDALONE transmission cooler for the truck? Thanks!

Yes. The radiator of a car that has an automatic transmission have a split compartment one for the transmission fluid. I’m 51 years old and this has been going on as long as I know of. Yes you can swap in a transmission cooler aftermarket and install it in front of your radiator

 

[SquireWhipple]

My concern is a cooler leak could mess up transmission, letting alone the fluids themselves.

The design to warmup transmission fluid is almost meaningless.

One thing I want to say is, based on my research on this, almost all cars with an automatic transmission have a cooler/radiator like this, not just Ford! To name one, Toyota 4Runner has this stupid design too!

I replaced a leaking eternal transmission cooler on my 2001 Sport. Amazon Hayden Automotive at first selected a cooler smaller than the original. Amazon was good on returns/exchanges. I ordered on two sizes larger and returned the first one, for a refund. No shipping on replacement or return. The second replacement was 15% bigger than the factory original. I still lost the transmission at 120,000 miles. I was never sure if the radiator also had a built in transmission cooler. It should be very rare to have a leak in the built in transmission cooler as it isn't exposed to the elements as in salt or other corrosives. Hoping yours goes well.

 

[CDW6212R]

As a heads up, the 6R60/80 transmissions, and others, have an internal flow value and will not circulate fluid to anything outside the transmission unless it is at full operating temperature. This nullifies external cooling measures getting the fluid temps lower than the target temperature set by Ford. This is also why flushing these transmissions isn't possible if the fluid temperature isn't at the proper level. So installing a cooler on some transmissions will help lower fluid temps in severe duty conditions but they won't drop the temperature below what is targeted by the programming.

That's great that they have a bypass system in them. I'll have to find out what that normal temperature range is, and judge whether it's cool enough.

 

[94Eddie]

That's great that they have a bypass system in them. I'll have to find out what that normal temperature range is, and judge whether it's cool enough.

The temperature setting my be something that can be changed in the programming.

 

[CDW6212R]

Thanks, hopefully that's no trouble. I'm not close to needing the controller yet, and so far the Quick Shift 6 is the only one besides the OEM versions. I wish for Pro M or Holley to push into that and add it to one of their systems.

 

[Fix4Dirt]

I replaced a leaking eternal transmission cooler on my 2001 Sport. Amazon Hayden Automotive at first selected a cooler smaller than the original. Amazon was good on returns/exchanges. I ordered on two sizes larger and returned the first one, for a refund. No shipping on replacement or return. The second replacement was 15% bigger than the factory original. I still lost the transmission at 120,000 miles. I was never sure if the radiator also had a built in transmission cooler. It should be very rare to have a leak in the built in transmission cooler as it isn't exposed to the elements as in salt or other corrosives. Hoping yours goes well.

sometimes they just do that due to age/ither factors like fluid filters, or just dumb luck. sorry to hear that though! mine has lasted 330k so far, nothing internal but fluid/filter

 

[cujo2006]

nothing really you can do imo except make sure everything looks tight, and occasionally check to make sure that it aint contaminating

Ok, so here is my 2 cents. For one I have to agree with EddyB, these have been in automatics for decades. Very rarely a problem. That being said I had an 08 Ranger 4.0 SOHC and an automatic that I had this happen to.
I will start by saying that as long as the engine is running you should have no coolant entering the trans because of the pressure difference. 30-40 psi in the trans lines will push tranny fluid into the radiator before the 12-15 psi coolant pushes into the trans. That all goes out the window the second you shut it off.
My story: On my way to work (20 min. drive) my Ranger started to shift funny slipping and just acting like it was low on fluid. When I got to work I checked the trans, obviously low, and added some fluid and looked for a leak. During this I just happened to look at my coolant tank to see it was very dark. I opened the tank and low and behold there was my ATF.
It took a second to realize what was going on but when I did I took a heavy rag and popped the radiator cap to the vent side and shut the truck off.
Long story short, I replaced the radiator and all is well, no coolant in the trans.
Probably rare for this to happen this way but it worked for me. I did however have to get some oil out of the engine but removing the thermostat and lots of Dawn and water fixed that right up.

 

[donalds]

Hmmmm Transmission cooler just fit in my intake

 

[Josh P]

Hmmmm Transmission cooler just fit in my intake

If it leaks, run the engine like a 2 stroke.