07 Denali: Large Roadtrip Upcoming. Advice?

[Paul Brambilla]

We are soon going to be taking our 07 Denali on a large, 4000 mile road trip. She has 130k miles and I'll be pulling a 6500 lb trailer.

Here's what I've done so far:
1. Replaced rear shocks, and compressor
2. Installed rear helper air bags
3. Installed secondary transmission cooler
4. Oil change + lucas stabilizer which has dramatically improved the likelihood of stabilitrac/traction control codes. However, it still happens periodically when running at high RPM's up the mountain followed by low RPMs / stopping.
5. (edit) Up' d the air pressure to 38 PSI instead of the recommended 34.

Things I haven't done but am considering:
1. LT tires. My P tires seem to have adequate tread left and so far I haven't really had a problem pulling the trailer with these tires, but I bet LT would be way better.
2. Drain/fill transmission fluid. Some say not to touch the fluid at these miles, others say drain/fill is ok, just don't flush.
3. What else am I missing?

Thanks for any advice!

 

[swathdiver]

I'd sure feel better with LT tires for towing on such a long trip. Almost zero chance of getting a flat with a 6 or 10 ply truck tire. Michelin LTX would be my choice.

Have you calculated your GVWR and GCVWR for this trip? How much will your truck weigh with everyone and everything in it, including tongue weight? How much will both weigh together; been to the scales? Does it exceed 14,000 pounds?

 

[PWMac]

2. Installed rear helper air bags
3. Installed secondary transmission cooler

Hope you had a good trip. What transmission cooler and helper bags did you install?

 

[Paul Brambilla]

Hope you had a good trip. What transmission cooler and helper bags did you install?

We are about 2300 miles into the trip, and so far it's been good. The transmission temps have only gotten above 200 once which I find incredible. It was the first climb over Snoqualmie Pass in 95 degree temps that did it. Since then it has remained cool.

The cooler I installed was the Derale 13503. The helper bags are the Air Lift 1000.

The only real challenge has been that the stabilitrak/TC messages have been coming on far more frequently than I'd like. It goes back off after a few miles of normal driving however so it hasn't really been a major problem.

Also, I did have to add some oil at about 1800 miles. I'll have to keep my eye on that.

Sent from my Robin using Tapatalk

 

[Danny3737]

Have you seen any red Ferrari's along the way?

 

[PG01]

Have you seen any red Ferrari's along the way?

Holiday road.....oho road....

*******

 

[intheburbs]

You might want to get your rig weighed, to make sure you're not overloading anything. I'd bet $1 that you're overloading your rear axle.
I also would've recommended changing the fluid in the rear axle. That's the weak point on your powertrain. If you're having to install helper airbags, you're overloading something.

Keeping the transmission too cool can cause problems as well. These trucks are designed to operate at 200°. On my trip a few weeks ago, I had the transmission up to 241°. I wasn't concerned at all. I really don't get everyone's urges to add extra/larger trans coolers. The stock cooler is more than adequate.

 

[Youngerjc]

You might want to get your rig weighed, to make sure you're not overloading anything. I'd bet $1 that you're overloading your rear axle.
I also would've recommended changing the fluid in the rear axle. That's the weak point on your powertrain. If you're having to install helper airbags, you're overloading something.

Keeping the transmission too cool can cause problems as well. These trucks are designed to operate at 200°. On my trip a few weeks ago, I had the transmission up to 241°. I wasn't concerned at all. I really don't get everyone's urges to add extra/larger trans coolers. The stock cooler is more than adequate.

I agree with the trans temp i was running 190-210 on a 3k mile trip no consern And she still runs like a beauty that was last month

 

[08grey]

190 Trans Temp no prob but why in that pic is you engine Temp so high. You gonna blow a head gasket.

Sent from my SM-G950U using Tapatalk

 

[intheburbs]

190 Trans Temp no prob but why in that pic is you engine Temp so high. You gonna blow a head gasket.

I was climbing 8-10% grades with a GCW of over 16,000 lbs in the Rocky Mountains. The engine was working a little hard. Once we reached the summit, we stopped and let the engine cool down.

It's not the first time it's gotten that high, and I'm sure it won't be the last.

 

[08grey]

Fans were on?

Sent from my SM-G950U using Tapatalk

 

[swathdiver]

I was climbing 8-10% grades with a GCW of over 16,000 lbs in the Rocky Mountains. The engine was working a little hard.

You're at least 2,000 pounds over weight.

 

[intheburbs]

You're at least 2,000 pounds over weight.

Oh, really?

 

[swathdiver]

My apologies, for some reason I thought you had a 1500. But by your own admission you were overweight at least some, hence those high temperatures. ;-)

 

[Rangel]

2500 series Denali?



Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[intheburbs]

My apologies, for some reason I thought you had a 1500. But by your own admission you were overweight at least some, hence those high temperatures. ;-)

I was two percent overweight - 16,340 lbs. It's not like there's some magic line, where if I'm underweight I'll see no elevated temperatures, and if I'm one pound overweight, I see a spike up to hot. More weight = more work = more heat. It's a gradual increase, and I know my equipment and I know what it can safely do.

On my previous trip to the Rockies with a 7,000-lb trailer, I saw trans temps as high as 235°. GCW was well below 16,000 lbs. So your statement "hence those high temperatures" is false, because I'd still have gotten that hot even if I was under my GCWR.

 

[swathdiver]

Alright Bill, I reckon you know more than me as I do not have a 2500. However, those that have them and have posted on towing, none showed engine and transmission temperatures that high. But context is key and I do not remember the details.

 

[intheburbs]

Alright Bill, I reckon you know more than me as I do not have a 2500. However, those that have them and have posted on towing, none showed engine and transmission temperatures that high. But context is key and I do not remember the details.

Those that have them probably aren't doing the things I do. I took the 7,000-lb trailer up I-70 in Colorado to the Eisenhower Tunnel, elevation 11,158 ft. From Denver, that's a 6,000-ft climb, higher than most of the highest parts of the country east of the Mississippi. Long grades (miles long) of 6, 8, even 10%. I'm running the engine at 4,000 RPM, or higher, for 15, 30 even 45 minutes at a time at full throttle. The transmission pump shaft is attached to the input shaft from the crank/torque converter. Spinning it that fast for that long of a time is going to dump a lot of heat into the transmission.

On this last trip, I took the 8600-lb trailer up Powder River Pass, elevation 9666' feet. Again, long, steep grades at high RPMs for quite a long period of time. And both times were during the summer, so we also were running the A/C, which also adds extra heat under the hood. Find me others "that have them" that have made these kinds of pulls/ascents with their trucks.

Sure, when I'm towing these trailers on relatively flat land, which is most of the time, the transmission runs around 210-220°, which is completely normal and expected.

 

[ken in md]

I have the same question as Rangel posted a few days ago - is it a 2500, or a Denali? The original post described it as an 07 Denali. But then I see the 2500 GCWR pictured. Which is it?

Very interested here as I am about to move FROM a 2010 Yukon XL Denali TO a 2013 Yukon XL 2500 primarily for the purpose of more towing and 2k more GCWR. We take the same type of long trips as described - 7100 miles this summer - our camper is only 5k dry but all loaded up - wife kids dog cooler stuff - we were pretty close to our Denali's 14000 GCWR. We weighed as high as 13,500 once and I wasn't too comfy with that. Our Denali OK...engine temp would rise on long grades though and that worried me. I did have two transmission coolers going and trans temp never went over 200, even in Bryce Canyon. Much different than without the extra cooler. But I did shy away from some routes to be safe and I don't want to do that. Hoping our 2500 will give us more peace of mind. Open to any opinions or comments on this.

 

[intheburbs]

I have the same question as Rangel posted a few days ago - is it a 2500, or a Denali? The original post described it as an 07 Denali. But then I see the 2500 GCWR pictured. Which is it?

Very interested here as I am about to move FROM a 2010 Yukon XL Denali TO a 2013 Yukon XL 2500 primarily for the purpose of more towing and 2k more GCWR. We take the same type of long trips as described - 7100 miles this summer - our camper is only 5k dry but all loaded up - wife kids dog cooler stuff - we were pretty close to our Denali's 14000 GCWR. We weighed as high as 13,500 once and I wasn't too comfy with that. Our Denali OK...engine temp would rise on long grades though and that worried me. I did have two transmission coolers going and trans temp never went over 200, even in Bryce Canyon. Much different than without the extra cooler. But I did shy away from some routes to be safe and I don't want to do that. Hoping our 2500 will give us more peace of mind. Open to any opinions or comments on this.

OP has a half-ton Denali. I have a 2500.

A 2500 should pull your trailer with no issues whatsoever. And there's no need to get a second transmission cooler. Dex VI fluid can handle much higher temps than older fluids. 200° is normal operating temperature after 30-60 minutes of driving. The "transmission hot idle engine" warning only comes on at 265°. I never got higher than 241°, and that was with a GCW at 16,300 lbs driving up to almost 10,000-foot altitude, with the A/C running.

The 2500 Suburban/Yukon XL are actually "sleepers." Because they share the same body as the half-tons, everybody thinks they're the same, but just beefed-up a little. The truth is that under the shared body is a completely different truck - bigger/thicker frame, bigger axles, bigger brakes, heavier-duty transmission, different/more-durable engine, heavier-duty suspension. They're completely different animals from their wimpier, half-ton cousins. You've made a great choice upgrading to a 2500. It will serve you well for many years and miles. Mine is at 170,000 miles and is still PERFECT. I've spent exactly $23 in repairs over the last three years, all the while beating the snot out of the truck.