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.

 

[West 1]

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.

Yep, had the oil pan off last year, I know clearly where they lines should be they are not there. The pan has the block off. plate rather than two lines feeding in. I will need to look behind the grill to see if it has on external cooler for the tranny in front of the radiator. I am thinking this Denali was sold without the standard Tow Package? A good idea to clean out the fins on the radiator, doubt if that has ever been done. I have only owned this one for about a year and a half so lots of unkown history in it.
The tranny fluid is brand new so no smell or dis color at this point.

I was just wondering if this is standard with the 6.2L when towing heavy, I had another Escalade, same tranny and engine, a 2007, only sold it because I preferred a White one. It never overheated on me but I never towed over 4500 lbs with that one and I can't say I ever towed on a 100*+ day with the Escalade. The 6.2L is a towing machine. Sucks gas pretty heavy but pulls hard when needed. I was slowed down by the engine temps not by lack of power on the long pulls.

Thanks for the comments. I may have some work to do to keep this one reliable while towing.

I could hear the fans pulling air but no idea if they were actually at High Speed or not.

 

[Foggy]

Also make sure you are in tow/haul mode AND you put it in the manual mode
so you are not hunting between 4-5th gears.. 6.2's like rpms, so keep it 4th unless on
a big downhill. Let that thing eat!!
NOT having the external trans cooler and NOT having the oil cooler certainly
is a downfall of your particular Yukon.. Strange.. but ...
The high speed fans won't kick in at all at highway ish speeds. I believe
only under 45 mph.. Which is a bad design.
Your fluid and trans is fine for short bursts at those temps. At least you are
keeping an eye on everything (many don't, till it's too late)
A good "tune" via HPTuners or Blackbear would def help out. Torque converter
strategy is much much undesireable from gm. That's why the TC bite the dust so early

 

[Marky Dissod]

Before I even bother reading anything else

... saw temps for the engine close to 240F and the trans hit 232F ...

Whenever my motor oil / coolant / ATF hits 230F, regardless of whatever, I change all three fluids if no other faults are present.
GM (and other carmakers too) put temp sensors where they are easy to install, not where the hottest possible temps are, meaning
if a fluid temp sensor reaches 230F, be sure that it's BEEN hotter than that somewhere else the whole time, that's why it's heating up in the first place,
which is why I change out ALL the fluids if ANY of them hit 230F, no matter how impressive Dexron6 or Dexron8HP-LV is.

... should have mentioned my idle Oil Pressure dropped to only 18 PSI when the engine was at 240* ...

Hotter motor oil ALWAYS equals lower pressure; if the motor oil were at NORMAL operating temp, oil pressure would be higher.
Again, somewhere, motor oil is hot enough to *offgas, which is why it's time to change it, unless you want to test a theory or something?
*a form of oil consumption caused by ... heat

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 1/4" thicker

Definitely this. Even if a radiator SEEMS to be in otherwise good working order, debris slowly builds up at the bottom of the radiator
(both an effect and cause of radiator aging) unless the radiator is regularly BACKflushed (no one does this often enough anymore, can't blame 'em).

high speed fans won't kick in at all at highway ish speeds. I believe
only under 45MpH, which is a bad design.

High speed fans never kick in over 35MpH, only low speed is available from 35-45MpH.
Over 45MpH, the headwind made by the vehicle's forward motion makes the fan motors completely useless
(except in the rare instance of a 45MpH tailwind while the vehicle is doing 45MpH)
Actually, since this is a GMT900, the fans are PWM modulated, so as the vehicle speed progressively increases,
the fan motors let the headwind gradually do more and more of the work (again, a mighty tailwind could mess things up)

A good "tune" via HPTuners or Blackbear would def help out.

HPTuners is just one of the possible software packages tuners of varying skill levels use, EFILive being another, a few still use TunerCAT-OBD2 as well (see my sig).
Don't know if BlackBear uses HPTuners or EFILive or another software package, he's earned his respect regardless of which software package he tunes with.

Torque converter strategy is much much undesirable from gm. That's why the TC bite the dust so early

GM's OE 'tune' sacrifices durability & longevity in several ways at several different points, including the TCC.
Some part of me still does not fully get why there are any people left out there who still have not yet bothered to get a proper/thorough ecm & tcm tune.
If it's the stereotype that tunes are only for leadfoots, that idea needs to die along with 'backpressure'.

 

[West 1]

Thanks for all the good tips. I really was interested to see what others see for temps in similar towing situations as all my previous LS engines have never had temperature issues even when heavy towing. I have had several 5.3's a 6.0L and 3 6.2L's now.

I will address the basics and always be careful hoping to avoid damage. In my working career I saw hundreds of blown up engines many due to overheat, lack of oil changes etc. I also saw many, many piston failures due to bad tunes. With this always in the back of my mind I have stuck with OEM engine tunes as I did not see piston failures with OEM tunes. I also like being able to run 87 octane. Call me cheap. My son is a very accomplished tuner. Can do GM tunes no problem but specializes in Audi and Porsche Turbo applicatons. He has offered many times to tweak my engine and I say No Thanks, it runs great as is. He thinks I am a sissy for this but as I said, I have seen melt downs many times from someone wanting just a little more power.
I was the guy that had to tell them, they have no warranty because the modifications killed the part. The pistons would show the combustion overheat situation that caused failure. The parts did not lie, close examination showed how the part failed and why in almost every case. Yep, I am a sissy when it comes to tunes. My son also says I need twin turbos which he is able and willing to do. I have refused that move also. Again, I am a sissy on this subject. At 30 years old I may have done all that but not now.

Done correctly I certainly know a tune can make you happy. Done wrong I have seen them make guys cry. A well planned out tranny tune might interest me as I do see the tranny could work a little better.