About Transmission cooler and radiator

[Justin J]

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!

 

[Fix4Dirt]

in my 2nd gen at least, part of the trans cooler is in the radiator stock. if you got the tow pkg, they gave you the radiator+another cooler. so yes they can mix. it aint hard to do that, ive seen others do it, havent gotten around to it myself. around that time, given youve got the 5r55e, get 2 stock coolers, or 2 big coolers, as low heat keeps these 5rs going for years

 

[Justin J]

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!

 

[Fix4Dirt]

imo its more to warm the trans on a cold day than to keep it cool, although it does a tiny bit. but standalone or just adding a cooler does wonders for these. change the fluid often (ie. for me its 30k), install 1 or 2 big coolers, and you should see good miles on these

 

[Justin J]

imo its more to warm the trans on a cold day than to keep it cool, although it does a tiny bit. but standalone or just adding a cooler does wonders for these. change the fluid often (ie. for me its 30k), install 1 or 2 big coolers, and you should see good miles on these

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!

 

[imp]

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” Ford engineers! DESIGNED TO FAIL!

Understanding the reasoning pre-empts your contentious replies. The additional cooler for transmission fluid outside of the radiator keeps temperature increase related to long term engine idling and high outside temperatures from getting the trans fluid even hotter under such conditions, as well as the cold temp conditions mentioned.

 

[Fix4Dirt]

Understanding the reasoning pre-empts your contentious replies. The additional cooler for transmission fluid outside of the radiator keeps temperature increase related to long term engine idling and high outside temperatures from getting the trans fluid even hotter under such conditions, as well as the cold temp conditions mentioned.

i wonder if they could make soemthing similiar to a block heater for the trans. imo i dont like the radiator and trans cooler being one, but i keep it there for the reasons you mentioned. however if there was something to warm the trans thats not the radiator, and i could run my external big ole cooler, i would hcoose that instead

 

[Justin J]

Understanding the reasoning pre-empts your contentious replies. The additional cooler for transmission fluid outside of the radiator keeps temperature increase related to long term engine idling and high outside temperatures from getting the trans fluid even hotter under such conditions, as well as the cold temp conditions mentioned.

I can see the reasons for the design, but it makes the (leak) failure TOO EXPENSIVE!

Routing transmission cooler inside a radiator can almost guarantee the transmission fluid temperature won’t exceed 212F (or that of the coolant). Standalone coolers may not have this edge! However, I see some big trucks use standalone transmission coolers, and they work fine with heavy tow.

 

[Fix4Dirt]

I can see the reasons for the design, but it makes the (leak) failure TOO EXPENSIVE!

Routing transmission cooler inside a radiator can almost guarantee the transmission fluid temperature won’t exceed 212F (or that of the coolant). Standalone coolers may not have this edge! However, I see some big trucks use standalone transmission coolers, and they work fine with heavy tow.

imo standalone is better all round, providing you have good airflow. but imo the main reason is for cold temps. this is jmo though

 

[Josh P]

The Eaton 10 speed manual transmission in my freightliner truck has coolant lines that go into the oil pan. Oil and water run through the engine and the head gasket is the only thing keeping them separate, is that a stupid design too?

 

[Fix4Dirt]

The Eaton 10 speed manual transmission in my freightliner truck has coolant lines that go into the oil pan. Oil and water run through the engine and the head gasket is the only thing keeping them separate, is that a stupid design too?

just curious, how many rigs you got? i know you have the aero, and i feel like ive heard of others (couldve been someone else with aerostars) also, are you an owner op?

 

[Josh P]

just curious, how many rigs you got? i know you have the aero, and i feel like ive heard of others (couldve been someone else with aerostars) also, are you an owner op?

3 currently, looking to buy 2 more. I got 2 jeeps, 2 merkurs a 06 ford LCF I got dirt cheap, and a 68 cougar.

 

[BKennedy]

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.

 

[07EddyB]

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.

 

[Justin J]

Thank you gentlemen for your comments! They definitely help us understand the design!

Any preventative measures can we take to prevent the transmission from being damaged by leaking coolant?

 

[Fix4Dirt]

Thank you gentlemen for your comments! They definitely help us understand the design!

Any preventative measures can we take to prevent the transmission from being damaged by leaking coolant?

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

 

[BKennedy]

Thank you gentlemen for your comments! They definitely help us understand the design!

Any preventative measures can we take to prevent the transmission from being damaged by leaking coolant?

If you are worried about it you can bypass the radiator by running the trans fluid lines to the external coolers. However, I think its fairly clear that you don't really have anything to worry about. I've had radiators fail, trans lines fail, but never where coolant and trans fluid end up mixing.

 

[94Eddie]

Thank you gentlemen for your comments! They definitely help us understand the design!

Any preventative measures can we take to prevent the transmission from being damaged by leaking coolant?

The only thing I know of is replacing the single o-ring OEM connection with a double o-ring one from Dorman. I did this on the replacement radiator I bought a couple of years ago. Having two o-rings is built in redundancy should one o-ring fail.

 

[Justin J]

Thank you all! I think I’ll just leave it alone for now.

 

[CDW6212R]

Thank you gentlemen for your comments! They definitely help us understand the design!

Any preventative measures can we take to prevent the transmission from being damaged by leaking coolant?

The pressure of the trans fluid is far higher than the coolant, easily over 100psi, versus about 16psi max for the coolant. That internal trans cooler is hardly ever heard of to fail. When it ever might fail, the ATF is going to go into the radiator while running, but when shut off, the coolant pressure will remain for a long while, and some will be pushed inside the transmission.

I prefer far cooler fluid temps than OEM, they want the coolant a little above 200*, and the ATF they expect to be very close to the same. Having the ATF go through the radiator, basically insures the ATF cannot run cooler than that. I want coolant to run around 175*, both for best power, and more margin for safety of the coolant overheating. Transmissions are killed by heat and malfunctioning of the VB and shift devices, lowering the temps is always helpful until they can get well below 150*.

The OEM 5R transmissions have an internal thermostat which doesn't allow ATF out to the cooling lines, until it reaches about 155*. That's likely inside most modern transmissions now.

If you install a very large external ATF cooler, then you can bypass the radiator cooler. A thermostat would be very beneficial if someone made one. There are many versions for oil coolers, they open at about 180* normally. I found one that is made with a typical thermostat "pill" inside it, the bimetal spring assembly in them. I got that but couldn't on first attempt unscrew the access cover. The cover is a hex shape outside, but less than 1/8" thick. I got a marine thermostat to cut apart for the pill, which is 145* rated. That would make an excellent thermostat control for the ATF cooling. I'd like to get that done right, and use that for all of my project vehicles. The Super Duty Ford trucks have several various sizes of ATF coolers. Members here have had good success with the long version of those, which can fit along the bottom of the Explorer radiator in front of it.