I towed my 4K pound trailer (5.5K loaded) from Los Angeles to Las Vegas today in 100 (was 110 at one point) degree heat. I had no issues towing except when going up one of the grades my transmission temp got up to 253 degrees while the engine temp was 185. I think that is a little too high. Should I add another or bigger transmission cooler? Is that normal?

 

I just towed from OH to TN in 90 or so degree heat. Around 9000 pounds and the highest temp I saw on tranny or coolant was 211 degrees. I know these trannys like the fluid hot better then cold. Not sure if yours got to hit but I doubt it.

 

Was the pedal to the metal up that grade? One thing to try would be to keep the rpms a tad lower, if you can...

 

I’m def no expert but 250+ seems pretty damn hot. I towed 6k up a decent grade albeit not for long and didn’t get over 220.

 

Ford spec's the NOT for the 10R80 to be 206 - 215F, so yeah, you were getting damm hot. Is your truck equipped with an ATF cooler? Certainly worth looking into if you tow a lot in those conditions. Extreme heat kills AT's more than anything.

 

Not really I was just kind of cruising along at 65 mph, I could have gone a lot faster but the speed limit for towing in CA is 55.

 

You were probably going up the Baker Grade, going from 960' to 4,100' in 19 miles, a notorious summer cooling system check, especially towing. They predict 113° today.

Were both your radiator fans roaring full bore? If you have active grill shutters, were they wide open?

That is the easy stuff to check. I tow a 7,500# boat/trailer on the hottest days around here, and so far the most I've seen is the tranny temp gauge moving slightly to the right of center on really hot days.

 

Is nobody else flumoxed by his engine temp? 185* is what I see with a 170* thermostat unloaded down a flat highway...no way a stock truck is running at 185 degrees when the transmission is 253.

 

You beat me to it. Ha ha. Yep, for those who don't know, coolant gauges on most vehicles are 'buffered', meaning the gauge/number doesn't move from about 185 to 235 (it might be higher on our trucks). When you activate digital gauge readings with FORScan (like I did), then you'd see actual numbers. OP didn't state his truck specs, but I think all trucks have a transmission oil-to-coolant radiator (at least mine does), which both heats up, and cools, transmission fluid, meaning tranny's temperature is always close to engine coolant temperature.

Anyway, 253ºF is way too hot IMO, but you didn't specify what you were doing. You might have been in too low of a gear, which is worse than higher revs, with less engine load. And if that hot and that steep, maybe a bit slower too, especially with a 2.7. Next time watch your transmission gauge and don't let it get above 230ºF, I'd say.

 

This was the second time my transmission dummy gauge went almost all the way to the right to the yellow section, however this time I switched to my digital gauges and that is where I saw my actual temp readings of 185 for the engine and 253 for the transmission. Does the truck save these temps anywhere?