2011 Yukon XK Denali Towing/Heat/Temp issue

[tkdgirl]

So 3 trips towing with my 2011 Yukon XL Denali and when the outside air temps are above 80/85, the engine temp gets a little too high (between mid and highest temps). Freaks me out so I turn on the heat to help. The trans temp hovers between 200-216 with the highest at 222 in idle/slow construction with hot/humid conditions.


Mechanic looked it over and said everything looks fine (hoses/radiator, fans and timing). The odd thing about this is the air temp also seems to get wonky. For example, the last time I towed the outside temp was only 80 but the internal temp said 96. Are both temperature sensors bad? Can I replace these easily?

 

[Geotrash]

So 3 trips towing with my 2011 Yukon XL Denali and when the outside air temps are above 80/85, the engine temp gets a little too high (between mid and highest temps). Freaks me out so I turn on the heat to help. The trans temp hovers between 200-216 with the highest at 222 in idle/slow construction with hot/humid conditions.


Mechanic looked it over and said everything looks fine (hoses/radiator, fans and timing). The odd thing about this is the air temp also seems to get wonky. For example, the last time I towed the outside temp was only 80 but the internal temp said 96. Are both temperature sensors bad? Can I replace these easily?

That's normal when towing with these rigs. Several of us have made some mods to our trucks to help keep the temps down. Some of them include a thicker double-row radiator, an aux transmission cooler in place of the dinky factory one but mounted below the bumper to keep it out from in front of the radiator, replacing the baffles on either side of the radiator, higher wattage cooling fan motors, etc. An easy first step you could take is making sure your radiator exterior is clean and free of dirt and debris.

Also, coolant boiling point oil these with the factory Dexcool is 265ºF, so there is a fair amount of margin built in. And, 222ºF on the transmission isn't an issue either, despite all of the charts of doom out there that show transmission life vs fluid temperature. The fluid is the limiting factor and it's good to 270ºF before it starts breaking down. GM engineers it to stay below 265ºF in all but the most extreme circumstances - e.g. towing in Death Valley.

 

[avalonandl]

You may need a radiator flush. These suv’s have marginal cooling for towing big loads. Your trans temps are ok.

 

[Foggy]

New Coolant. Transmission Full Service- Pan/Filter... Not the flush BS
Make sure your serpentine belts and tensioner are less than 5 years old/under 75K miles
Regular maint items like plugs, wires, air filter.. Make sure your front area where
the ac condenser/radiator aren't all filthy with road debris/bugs/salt/cotton wood seeds
ALL this kinda stuff is little by itself, but it really stacks up to create a situation that you are seeing.
Servicing the front and rear differential and transfer case too... It's all points of heat/friction, extra power
needed to get it moving, therefore extra fuel/heat needed

Depending on your location, you could run a higher percentage of distilled water to dexcool to help
dissipate heat better... I'm in the midwest, so I run 70% distilled water + additive with my dexcool...
But late in fall I drain and switch to 50/50...