2007 5.4 towing 5400 lb TT. 95 degrees outside temperature coming home, all interstate with the end few miles in town then parking in lot.

Radiator temperature stayed right around 197 plus or minus a few degrees.


Transmission stayed around 155 on interstate. Then when I got in town and parking, it rose to about 188. I put it in neutral and idled for a bit before shutting off and it never came down, at least not until shutoff.

So what is the maximum safe temperatures for both?

What are others seeing.

By the way, I'm using a OBD Reader with phone app.

 

I can't say what is normal on the 5.4. But the transmission temp on my 2014 with a 5.0 stays between 195 and 205 during warmer months regardless of whether I'm towing or not. During colder months a few degrees cooler. That seems very common with that engine based on what I've read.

There is conflicting data out there. But from what I can determine as long as transmission temps are under about 200-210 the fluid will last a long time. The more time you spend with it at or above 220 the more often it should be changed. Ever let it get to 230 and it needs to be replaced ASAP.

Personally 155 degrees on transmission fluid seems too low. I'm not sure I'd trust the gauge.

 

I had an '01 Explorer that I towed with and I'd added a trans temp gauge (no fancy info screen in those days) and towing our 4000#+ trailer raised the temp to 210 for a short period of time (10 minutes or so) a number of times over the years. I had 150K on the odometer when I sold it and never had an issue

 

NC, does your truck have the tow package and large oil to air trans cooler with thermostat?

 

Yes. Tow package with external cooler.

I presume it has a thermostat. The app is reading it from the OBD port.

 

Mine runs at 199 all the time, it will heat up to 206 when I'm pulling the tt up the Rocky Mountains

 

I was pulling our 30' camper through central texas last weekend and it was 98 degrees out. Engine temps were 220 to 230 per the torque app. But the gauge in the dash never moved. Trans was steady 208 to 210. Anyone see this as abnormal? Speed was between 65 and 70.

 

As long as the tranny temp doesn't go over 225°, you're good to go. You probably won't overheat the engine or tranny unless you try to drag a heavy trailer out of Death Valley at 75 MPH with ambient temp over 120°. Or same hot steep grade and you poke along with the tranny torque convertor unlocked. So keep the speed up to at least 45 MPH to keep the torque convertor locked, and downshift to keep the engine RPM up to over 2,000 with speed down to about 55 MPH when working the engine hard.

 

I had been wondering this myself, specifically the transmission temp when towing. After much online research and input from several techs at my local Ford dealer this is what I have discovered.

The applies to the 6r80 transmission (6 speed). I have not researched the new 10 speed.

Disclaimer: As this has not come from a Ford engineer I have no way to verify it is correct.

The needle gauge (idiot gauge) on the dash only has four positions:

Cold: 0 - 50 F Normal
Mid: 50 - 220 F Normal
Elevated: 230 - 250 F (Yellow Area)
Danger: 250+ F (Red Area)

On top of only four positions, it is programmed to move slowly as the temp rises. If you only briefly hit a transmission temp of say 230+, it my be slow to move and most likely will rise a bit from its normal position, but not go all the way to yellow instantly.

All this is to say, don't use the needle gauge. When towing on a hot day up a grade and you suspect things are heating up, have the transmission digital temp reading out on your dash so you have a real time display of the actual temp. This way you will know if it is still going up, or starting to cool.

In talking with the techs at the dealer, they said that brief periods of running hot (in the 230s) will not hurt the tranny. By brief they said under 30 min. They also did say that if I go over 225, the best thing to do is pull over for a bit and let it cool. You can also try gearing down if possible.

The best advice is to always avoid going over 220, then there is nothing to worry about. There are some situations where that is unavoidable in the moment though....

 

Based on my driving observations. Smokey had this right.

Flat and level highway cruising keeps temps happy. When climbing, down shift, keep torque converter locked, on my 3 speed that means shifting to 2nd on steeper climbs and holding about 45. That puts the RPM's around 2700 to 3000 which is no problem. When I slow, start driving around town, or the lot to store trailer, temps start to climb.