Recently towed a trailer load of calves (approx. 14K including GN) noting transmission temps broaching 250 (243 degrees to be exact). It did the same thing last summer pulling a load of hay (roughly same weight). Had the tranny serviced thinking I road it rough during the trip. Understand Ford designed trannys for higher temps, but excess of 240 degrees F too high?

Thanks,
Rick
2012 F250 SD Lariat 4dr SB 72,000 miles

 

That sounds a little high to me but I didn't design the cooling system for these trucks. I would think synthetic fluid would take those temperatures better but FoMoCo has to be aware of the transmission getting this hot. I feel more comfortable in 220-230 degree range and I have considered installing an external cooler downstream of the radiator to facilitate those temperatures.

 

220-230 for me seems to be the max. You may want to add a fan to the trans.

 

I see 230s trans temps when oil temp is also maxed out. They fall after cresting the summit of a grade. The liquid to liquid trans cooling system is doing it's job. The secondary system also cools the air charge (CAC), oil and EGR. every one of those things is hot during a hard pull.

What is the secondary cooling system temp under same condition? Fan RPM?

 

When I used to tow my 5er when I had my 2013 my tranny temps where often in the 240's. Research I did at the time indicated that this is normal. From what I understand the tranny was designed to operate at higher temps than what we are used to. IIRC there is an ex Ford engineer on one of these forums that confirmed this. Hopefully he sees this and confirms.

 

When I picked up my new F-350 dually in Texas and drove it (unloaded) to New Mexico my tranny temps was running at about 230. It also threw a engine code at that time. The dealer check my secondary coolant and found it to be low. Since that was corrected by the dealer my tranny temps have stayed at or below 200 when run unloaded. I have not seen 230 even when towing my 5th-wheel.

 

I see Ford transmission temperatures as excessive and am developing/testing a kit. I typically tow 18K (5th Wheel) and typically operate in the 198-205 range. On long pulls I may see 216-220 but recovery is very quick. Heat is not a friend to automatic transmissions and these things are expensive.

 

Cooler is better, but keeping the transmission under 300F is best depending on the fluid used of course.

 

Kayaking,

You're brave. I don't like to see trans temperatures much above 200. When I'm towing, I always have the trans temp on the display giving me a good idea on how things are doing below my feet.

 

I don't have first hand knowledge of the 6R140. I never worked on it.

Before I left Ford in 2007 we were talking about raising the transmission operating temperature. The first step in that was adding a thermostat to the 5R110W. We were talking about going higher than that, but I left before any decision was made.

I was part of a team at Ford that supplied transmissions to an off road race team. They had the trans coolers in the bed of the truck to protect them from rocks and other nasty stuff found in the desert. They had large fans to force air through the coolers because they didn't get any natural airflow.

At one race, the fans failed. I forget now why they couldn't fix them during the race, but it wasn't possible. They were leading the race, and they made the decision to keep going as long as it would go. The trans temp gauge was pegged at 320°F for hours. The trans never faltered. They won the race.

After each race, we got the trans back for a teardown analysis. When we tore this trans down, each clutch showed some signs of heat, but was not damaged. The only thing we found that wasn't right was each solenoid. All of the solder in every solenoid had melted and was laying in the pan.

Solder melts at 451°F. So we don't know exactly how hot the trans was, but it was at least 451°F. And it still worked. And that's also why I recommend Mobil 1 Synthetic ATF, which is what that trans had in it. That's also why I don't worry about a 6R140 running below 250°F.

 

I'm right there with you, but warm and fuzzy vs what a transmission and its fluid can actually deal with are 2 entirely different things. With the cooling system Ford gave us and the newer LV fluid I doubt the temperature of a 6r140/10r140 will ever be why it fails even if the trucks are abused and well overloaded according to factory recommendations. Transmission temperature just isn't something to worry about on these trucks. Just keep fresh clean fluid & filters in them and keep on keeping on!

 

I don't believe any of the "designed to run hot" hype. Tribologists (such as the "Motor Oil Geek" Lake Speed, Jr.) on YouTube will tell you that even modern trans fluids start to break down rapidly beyond 230F. The ideal temp range for trans fluids is about 180-190F.

My 2019 stays below 200F always. Towing, not towing, cold outside, hot as Hades outside, up hills, down hills, city, highway, doesn't matter to my truck....it NEVER has high transmission temps and that's exactly what I expect. If my trans fluid ran at 230F or greater mine would be headed to the shop.

 

I'm with you!
I removed the thermostat in my 6R140 valve body and never see over 230F temps even with heavy towing. Unloaded driving I am at 160-170F. Changed my Trans fluid about 4 weeks ago at a little over 65K miles and came out looking new.

 

I'm trying to remember but believe a user here had either a 11 to 16 gen F350 or a F450 and installed a Mishimoto trans cooler, IIRC (or maybe it was an oil cooler as he towed heavy -- I'll try to find the thread) and was very satisfied. This cooler integrates into the stock liquid trans cooler circuit. If anyone is worried about high trans temps, this may be worth looking into. There was another aftermarket company that sells a trans cooler for the 6.7 as well. I'll try and find that to post here as well.

Another thing to remember, the Alumina Dutys 17 plus trucks use the primary cooling system to cool the trans fluid whereas the 11 to 16 trucks use the much cooler running secondary system to cool ATF.

 

You can add coolers all day long but you will never get past the 180F thermostat in the valve body. Higher oil/fluid temps are all about EPA compliance to include LV/ULV fluids and oils.