I've been on the road with my 12k fifth wheel since late May. Once I got out west and started pulling grades, I also noticed my transmission temps would sometimes be pretty high. A friend from Cali with a 2019 350 6.7 made a temporary bug screen for the both of us while we were in Idaho; he was concerned about rocks and bugs as we headed into the Canadian Rockies, Yukon and then Alaska. It was made out of fiberglass screen material, so very small holes in the screen. After a few grades up in the Rockies, I could smell my transmission at every stop we made, so I took it off and chanced the rocks. He was pulling a much, much lighter TT and had no issues. I've not gotten any red light warnings except when I shut it off hot and then restart fairly quickly before it cools down. I think the highest sustained I've seen is 226 (transmission, not oil temp). My friend with a Chevy duramax keeps asking me what my temps are --usually low 200s into 210's---and then bragging that he's less than 160s. I've countered him by saying Chevy and Ford must measure the temps in different places, but I don't really know. The Ford manual doesn't have a specific entry, but I did find one mention of 'normal' operating transmission temps up to 216. Any thoughts? It's hot--I'm making my way east again and have been in the scrubland of eastern Oregon and now Idaho. I actually turned off my a/c today pulling a grade because I was in the 220s. Am I worrying about nothing?

 

In a word, YES, you are worrying about nothing.

225 degF is NOT hot for any decent oil. Even 250F sustained is not a big deal. In many SAE tests, the sump temps are set at 250F.

 

Great, thanks. Then I'm gonna relax and enjoy the ride.

 

Do you have your Forscan mod to show the digital temps of engine oil and transmission, coolant above the Gauges? When the temps get really hot, they show YEllow, and then Red, if you ain’t yellow or red, just enjoy the ride. There are several other threads about how this transmission does in fact run much hotter than previous versions and it is meant to do so. Replace the bug screen with a simple roll of window screen down in front of everything, it’s not restricting airflow. The more bug guts and bent coolant fins, the less cooling you actually have.

 

Pulling passes in the Rocky Mountains with my 11k GVWR trailer I routinely hit 230° F on the transmission temperature. The highest has been 232° F I believe.

I wouldn't run a bug screen on my truck. I want all the air flow I can get.

 

My trailer is 10K and the highest Ive hit was 207* in my 6.2 going up a 9 mile 5% grade which was around the Appalachians.

 

Somebody on this forum looked at the logic. He found the engine fans don't kick on to cool the transmission until 245. 6.7lilter. Maybe it was a youtube video. I know the thermostat for the transmission minimum operating temperature is 195

 

So does the Duramax run a lot cooler or is it what I kept telling Jerry when he went on and on about how much cooler he was running and that Ford measures it in a different spot? He told me he changed the transmission fluid in his Chevy to some expensive product recommended by Allison and was convinced it made a big difference.

 

At one time you always wanted transmission temps below 180F. Ford has revised their design to operate at much higher temperatures. GM hasn't. I can't think of one transmission failure i read about on this forum on the 6.7.

 

Ah, thank you!

 

When I have the transmission temp Guage pulled up in the "my view" screen, once the transmission temp reaches 210 it displays the actual temp in digits right above the guage. Mine has gone to 217, but I am thinking, guessing, that it is a bit of a heads up that the tranny Temps are getting up there, not too hot, but just a way to let you know to keep an eye out. Once the Temps fall below 210 the digits disappear. So your back into no concern territory.

 

Window screen blocks 33% of your airflow.

 

You have to completely recalibrate yourself as to what the definition of hot is. Conventional wisdom isn't current with these trucks.

Under the lightest driving imaginable, my temp is 196. That's about the floor. For any stop-go driving, highway speeds, or anything approaching a normal drive, I'm in the 205-210 range. When I'm towing 7,000 lbs, I'm in the 205-215 range on flat, easy terrain. For easy hills, I'm in the 210-220 range. For 6-7% grades, I'm in the 215-230 range.

I think 232 is the highest I've seen. Usually, at that point, my coolant is at that level and the fans kick on. In 2-3 minutes, my coolant drops down to 187 and that pulls the transmission temps down a few degrees, too.

BTW, I'm driving at 5,000' normally and I'm in the 6,000 - 11,000' range when towing. Ambients are 65 - 85 and don't seem to affect the numbers much.

 

We were towing our our fifth wheel camper trailer today in Florida, dash showed 98 to 100 degrees outside, 65 to 72 mph, transmission temperature went to 210 a few times. Flat, no wind to speak of, just hot and humid. But there has to be a reason they decided to make the actual temp show up in digits starting at 210. I am not saying that is too hot, just thinking there is a reason.

 

We were towing our our fifth wheel camper trailer today in Florida, dash showed 98 to 100 degrees outside, 65 to 72 mph, transmission temperature went to 210 a few times. Flat, no wind to speak of, just hot and humid. But there has to be a reason they decided to make the actual temp show up in digits starting at 210. I am not saying that is too hot, just thinking there is a reason.