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.

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[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.

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[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.