I know folks have beat this issue to death but i think if these type things are repeated form time to time it keeps the info fresh in our memories. Today i got a call from my dad while he was on the road towing with his E99 F550 with 38' horse trailer/camper. He called me concerned about his trans temps hitting 195*. I tried to recall what I had read in some of Mark's post about trans temps and I told him that 175-180ish is ideal and that 195 is not a concern when towing heavy, not even 200 would be a concern. It could run 220 all day long but that if it got to 220 not to just shut it off, put in park and let it idle and cool down. Also told him to run it 230 for no more than half hour or so before stopping to let it cool.

I got on here and did some searching thru the trans threads and pretty much confirmed what i told him (my memory does work after all these beers) with the exception that Mark says to run it 250 for no more than half hour. But i also came across some comments concerning the e99's and the lack of an OTW trans cooler as part of the radiator. Does anyone know if this was also the case for the e99 F550? (assuming since it was designed to haul heavy loads it may have a better cooling system) So if this is true the advise given to stop and let it cool would not be as effective with only a oil to air cooler? Would need movement to force air across the cooler? Unless of course there is an electric fan mounted to the cooler? If wanting to swap to a radiator to one with the OTW cooler would I be okay just ordering a radiator from say an '01 model year? Does the 6.0 cooler also match up with the e99?

 

The idea about not shutting it down is to allow the pump on the transmission to flow the fluid through the cooling system. Whether you have a OTW + OTA or just an OTA cooler the fluid moving through it will cool down. Once the truck is no longer driving, you are already helping it cool down since the load is removed. With the fan pulling air through the grille and across the OTA cooler it will drop the temps.

 

Yes, the 6.blow xmsn cooler will work in the e99. Same truck as the late 99 in the aspect of cooler fitment. That mod, in my mind, is one of the best you can do. Your dads truck has the same engine and tranny that I do, but I pull heavier and keep cooler, garaunteed! You can get a new one cheap, then a few bucks for some brass adapter fittings at Lowes or HD, maybe some extra hose (I used diesel fuel tubing from a boat store) and it'll keep it so much cooler. Plus the e99 has the air to air cooler, even though my radiator as the ports for it. I typically run 100-140* empty and 120-180* grossing 26-30k on level ground.

 

The F550 cooling is identical to the F250, so no, his truck does not have a cooler in the radiator, unless it was added after the truck was built. Many trucks were retrofitted with radiator coolers.

The best cooling setup is a radiator with a cooler, then to a 6.0L cooler.

 

Ok guys, thanks for the comments. I sent the following to my dad this morning. This is pieced together from several different threads and comments that i condensed into a single list. I thought i would post it here as well in case anyone using the search feature in the future could find this info all in one post. If there is anything incorrect, please correct me if i am wrong.

1.The 4R100 auto trans typically runs about 75-80* above ambient air temperature (eg. If 80* outside then trans temp should be about 160*, if 100* then 180 on trans, not an exact measure, but pretty damn close.)

2.The early model Super Dutys do not have an OTW (oil to water) cooler installed in the radiator. There is only an OTA (oil to air) fin type cooler in the early years. In 2001 they added the OTW as part of the radiator. What this means is that the cooling capacity is not the best with early truck in stock configuration, Ford recognized this and corrected the issue.

3. The ideal temp for this transmission is 175*, unloaded.

4. If towing, temps will climb higher, there should be no concern with anything below 210*, if towing this is to be expected.

5. Concern should start at 220. You can run all day long at 220* but remember not to shut the engine off if 220 or above. The idea about not shutting it down is to allow the pump on the transmission to flow the fluid through the cooling system. Once the truck is no longer driving, you are already helping it cool down since the load is removed. With the fan pulling air through the grille and across the cooler it will drop the temps. This does not mean to slow down and barely move while allowing to cool down. It means stop, put in park or neutral. The slow crawling will actually make the temperature rise as that is when an automatic trans builds the most heat.

6. While not recommended, you can run with temps up to 250*, but for no more than 30 min before stopping to cool down. Just like Kenny Loggins, you are now in the danger zone and will ruin the transmission.

7. By far the best upgrade you can do to help with the cooling capacity of the transmission is to install a transmission cooler from a 6.0 truck. The coolers on the 6.0 have a much greater cooling capacity than that of the 7.3.

8. The best cooling setup is a radiator with a cooler, then to a 6.0L cooler. The 6.0 is a direct swap with the 7.3 in regards to mounting location, but will need some threaded fittings and high temp hose to make the plumbing connections as this part is not a direct swap.



The radiator w/ cooler can be purchased for about $250, and the 6.0 cooler can be had anywhere from $250-$400 depending on where you get it.

 

Didn't think going from radiator to 6.0 cooler would be best, as that means you will raise the tranny temp to your engine temp (190-210*) and then trying to cool it down again. I guess it would work, but I never see over 140 empty, and 180 towing, and I tow up to 21k all the time. But hey whatever keeps you from a $3000 rebuild LOL!

 

You will not be heating it up to 190-210, that is the output temperature. The OTW cooler is in the bottom of the radiator. Since the radiator is cooling the fluid, it will be much cooler at the bottom. Mark listed a number one time and I believe it was something pretty low like 120-130 degrees there. Easy to check, just use a thermo temp gun and hit the bottom of the radiator.

 

All of those items come from Mark, aka, the Ford transmission engineer, I think if anyone would know it would be him. All of these items were in a bunch of different posts that i found from the search function, all i did was re-state what mark has already said, but i put it in list form so others can find all the information in one spot if they also use the search feature in the future. That comment was also referring an E99 which apparently does not have the otw cooler as part of the radiator.

 

good work organizing that info.

 

That darn myth just won't die! I'll try again.

The transmission cooler is in the cool side of the radiator. It NEVER sees engine temperature. If the fluid leaving the radiator was at engine temperature, why would you even need the radiator, if the fluid leaving is the same temperature as what's coming out of the engine?

The answer is that the engine coolant is cooled in the radiator. It's quite a bit cooler by the time it crosses the radiator and gets to the trans cooler. It is cool enough that it is always cooler than the ATF flowing through the cooler. ALWAYS.

I am not sitting at my computer imagining how all this works. I spent years instrumenting trucks and measuring the temperatures in the radiator, transmission, coolers, and lines. I measured everything that had to do with cooling the transmission. It was my full time job.

I measured in ambient temperatures between -40F and +115F and NEVER found a condition where the radiator warmed the ATF. Never even came close.

 

Same principle applies to the ZF6? Or that trans just doesnt produce enough heat, to worry about the "6.blow" added cooler...lol, good one Mongo.

 

Mark, I have to ask why you think the Radiator cooler is a good Idea. Im not really questioning your back ground but the theory.

I build and race the Taurus SHO all around the country and for years have been eliminating the radiator cooler on the ax4n and 30 degree colder temps but just adding a large external cooler. Highway speeds in the SHO (96-99) the trans will be in the 200 range, a little higher climbing hills. after the removal of the radiator from the equasion and adding a cooler on the same road with roughly same temps I will see 165-170.

the fans come on at 208 degrees and I personally think that my trans fluid passing through that cooler with come up to the coolant temp before going to the external cooler (stock) which is super small. Never getting the chance to cool down.

The new 2010-up SHO uses the Ac Condenser which blows my mind as they are always red hot! in process of elimnating it now as I have already melted one of fords new 6f55 on VIR this past summer.

Now I dont tow heavy at all, my truck weighs in with trailer at 11010, and Ill add 5k to the trailer max most of the time and from reading all the horror shows, but in 5 months a have towed 40000 miles and need a stable truck. really wish I could go steal my Allison's back out of all of my recent duramaxes.. lol

 

Here's why:


Taurus cooling, both engine and transmission, is GROSSLY undersized. I fought that for several years when I worked on the AX4S in the Taurus, Windstar, and SHO.

The radiator has barely enough capacity to cool the engine, but definitely not enough to cool the engine under sustained WOT operation, such as racing. Add the heat from the trans to the undersized radiator and both the engine and trans will get too hot.

 

The ZF6 makes A LOT less heat than an automatic. I never measured a manual trans to know if it has enough cooling or not. That wasn't my area of responsibility as an automatic transmission engineer. Someone else in another part of the company did that and didn't share their findings with me.

 

WOW. Hang in there Mark. There are many of us who read, pay attention to and respect your experience. But, I do appreciate some of the questions, as I learn something new most of the time.