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Old 07-03-2015, 07:16 PM   #1 (permalink)
Block Heater
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Mountain/high altitude driving

I'm not sure this is the right place for my question, so if not, moderator, please feel free to move.

We have a 2012 3500 Chevy D/A dually that we use mainly to pull our 38' 5th wheel. It only has about 18,000 miles on it. We are planning a trip later this month to Yellowstone and my husband wanted me to see if there is anything we need to know/do for mountain & high altitude driving. We've not done any performance mods to it. Thanks.

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Old 07-03-2015, 08:53 PM   #2 (permalink)
Diesel Boss
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nope. modern electronics take care of all the adjustments needed as elevation changes yes, you will loose some performance, not as much as a non turbo engine, but still loose some as altitude increases.

2015.5 Sierra Denali CC/SB/4x4 Stone Blue Metallic/Jet Black Interior
pinstriping by Bob Spencer AKA "spirit", undercover FLEX tonneau cover, color matched bug shield and vent visors, raintracker rain sensing wipers, X-treme coating bedliner, gm trailering camera system, coolant filter, Bilsteins, remote tailgate lock

04.5 LLY CC/SB/4x4 Allison Dark Green Metallic/Dark Charcoal Grey Interior
Webasto Hollandia Sunroof, Carbon Fiber Interior Trim, color matched bug shield & vent visors X-treme coating bedliner, Access roll top cover, Westin Step Bars, Lubrication Specialists Aux fuel filter, coolant filter, CAI, Michelin LTX tires, Manual High Idle Mod, Bilsteins, prodigy brake controller, raintracker rain sensing wiper controller, Remote autolocking tailgate, Reese Titan Class V hitch, Allison badges, Pinstriping by Bob Spencer, 4x4 decals removed, color matched door handles, 4 headlight mod, Homelink console.

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Old 07-09-2015, 12:32 PM   #3 (permalink)
Diesel Apprentice
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yup, what he said.

You will not have any troubles.

tow haul mode, engine brake if so equipped. set cruise control. enjoy the scenery.
13 Denali Dually D/A Steel Grey

Last edited by tmm2good; 07-09-2015 at 12:33 PM.
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Old 07-09-2015, 05:05 PM   #4 (permalink)
Diesel Head
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May need to re-jet the carbs but that's about it. LOL
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Old 07-11-2015, 10:41 PM   #5 (permalink)
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Don't be afraid to run a little higher than average rpms during the climb 2300-2500, it will handle that without an issue. Now on the way down, pick a gear and stick to it, only using the service brakes in short intervals. During engine braking rpms can climb higher than usual without causing any issues, ball park up to 3500 is my limit for engine braking.
2012 CC/SB 2500HD LML LTZ Blk/Blk
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Have some go fast stuff awaiting a built transmision

If it's spotted in southern Wisconsin, there is a 95% chance it is someone else driving it!
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Old 07-12-2015, 05:10 PM   #6 (permalink)
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Just leave it in auto with the tow/haul and exhaust brake set.

The engine and trans 'talk' to each other extensively regarding need to shift (up or down), resulting power availability and engine rpms. The system is a lot smarter than we give it credit for - unlike the days of engines/trans that operated independently.
2018 L5P Sierra 4x4 SB Denali
Sold 2011 LML Sierra 4x4 CCSB SLT
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Sold 2004.5 LLY Sierra 4x4 ECLB SLE
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Old 07-12-2015, 10:36 PM   #7 (permalink)
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Moved to Towing...

As mentioned above, you'll be good to go with no changes. Just turn on the exhaust brake, set the cruise control, and enjoy...
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Old 07-13-2015, 02:44 AM   #8 (permalink)
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I don't know about the newer generations, but my LLY clatters louder above about 8000 ft. (not sure, could be 6-7000 ft., too). It concerned me the first few times it happened but now I expect it. It's mostly noticeable when coming to a stop and idling (like at the top of Sonora Pass where it's about 9500 ft.). Of course, I'm gasping for air about then, too.
2004.5 Silverado 3500 SRW 4x4, D/A (LLY), Ext. Cab, Long Bed
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Old 07-27-2015, 07:52 PM   #9 (permalink)
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I live in SW WY and my LLM does great here. I got better mileage here than when in OK but the temperature my have had some to do with that.

Enjoy the scenery.
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