2008 Denali Towing Temps

[West 1]

I have an 08 Denali, 6.2L and 6L80 with the new Luk converter now installed.

I have owned several of these GM Suv’s with the LS engines. I have never had one heat up while towing the temp always stayed pretty much dead on the thermostat temp.

Last weekend I had to help my son move. I pulled a car trailer twice from old home to new. Each load was maybe 6500 pounds, Car trailer loaded with a car. I think the Denali is rated to pull around 8,000 pounds.

There were several long hills and outside temps were right at 100* each trip so conditions were tough for sure.

Pulling one long hill on each trip, maybe a 3 mile pull, I saw temps for the engine close to 240* and the tranny hit 232* on that pull. Once over the long hill the temps slowly came back down.

The engine pulled like a beast and maintained around 60 mph on that pull.

I was surprised by the temps reached, did not expect that at all. My previous 5.3L Yukon pulled heavier loads working harder in lower gears, could not pull at the same speeds but the Temp of the engine stayed very close to 200*?

The tranny fluid in this Denali is only 2,000 miles old but I don’t like that it was exposed to 230* even though it was for a short time. The engine was flushed last year and new coolant and hoses were installed. Never showed high temps till this hard pull last weekend.

I did add a large tranny cooler to both of my previous Tahoe and Yukon’s with the 5.3L but have not added a heavier external cooler to this Denali. Also this Denali does not have the engine Oil Cooler from the factory. I should have mentioned my idle Oil Pressure dropped to only 18 PSI when the engine was at 240*. I cooled it by lifting the hood and holding the idle at 1000 RPM for several minutes till the temps came back down.

That is a lot of words to ask if this is normal with the 6.2L while pulling or if my cooling system is not up to par???

The engine made all the power I could ask for, seemed to run absolutely perfect but I did not like the temps at all but I understand I was towing in a worse case scenario. Heavy load and very high temps outside.

 

[j91z28d1]

I'm not a heavy tow guy so others will know much better, but if the radiator is original from 08. I'd start there replacing it with that Denso one guys here have good luck with. good price, oem quality and I believe a 1/4in thicker

could also double check your fans are both working on high speed mode.

 

[intheburbs]

Check the fins of the radiators for debris/blockages. I just had some work done and my mechanic buddy said he blew a bunch of cottonwood seeds out of my radiator.

230° for the trans fluid for a few minutes isn't the end of the world. Dex 6 is pretty stout stuff, and the "trans hot idle engine" warning only trips around 265°. My personal all-time high score is 243°. I just change the fluid more frequently. Not just a pan drop - full fluid exchange, all 16 quarts.

Pull your dipstick, and wipe it with paper towel. Is it still red/pink? Brown is ok, black is bad. How does it smell? Oily/detergenty is good, any burn smell is bad.

 

[Doubeleive]

I have an 08 Denali, 6.2L and 6L80 with the new Luk converter now installed.

I have owned several of these GM Suv’s with the LS engines. I have never had one heat up while towing the temp always stayed pretty much dead on the thermostat temp.

Last weekend I had to help my son move. I pulled a car trailer twice from old home to new. Each load was maybe 6500 pounds, Car trailer loaded with a car. I think the Denali is rated to pull around 8,000 pounds.

There were several long hills and outside temps were right at 100* each trip so conditions were tough for sure.

Pulling one long hill on each trip, maybe a 3 mile pull, I saw temps for the engine close to 240* and the tranny hit 232* on that pull. Once over the long hill the temps slowly came back down.

The engine pulled like a beast and maintained around 60 mph on that pull.

I was surprised by the temps reached, did not expect that at all. My previous 5.3L Yukon pulled heavier loads working harder in lower gears, could not pull at the same speeds but the Temp of the engine stayed very close to 200*?

The tranny fluid in this Denali is only 2,000 miles old but I don’t like that it was exposed to 230* even though it was for a short time. The engine was flushed last year and new coolant and hoses were installed. Never showed high temps till this hard pull last weekend.

I did add a large tranny cooler to both of my previous Tahoe and Yukon’s with the 5.3L but have not added a heavier external cooler to this Denali. Also this Denali does not have the engine Oil Cooler from the factory. I should have mentioned my idle Oil Pressure dropped to only 18 PSI when the engine was at 240*. I cooled it by lifting the hood and holding the idle at 1000 RPM for several minutes till the temps came back down.

That is a lot of words to ask if this is normal with the 6.2L while pulling or if my cooling system is not up to par???

The engine made all the power I could ask for, seemed to run absolutely perfect but I did not like the temps at all but I understand I was towing in a worse case scenario. Heavy load and very high temps outside.

Are you sure you do not have oil cooler???? as far as i know all of the gmt900 denali have a oil cooler (drivers side of radiator) and it "should or may" have the small external transmission cooler up in front that runs parallel with the one built into the radiator on passenger side, that one may have been optional though.