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GMC 3.0 Duramax vs 6.6 Duramax

mxracer317

mxracer317

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Looking for some thoughts on switching from a 2016 GM 6.6 Liter Turbo Diesel V8 Duramax LML engine to a 2024 AT4 3.0 Duramax.

Primarily use the truck for pulling a wake surf boat (7800lbs) or enclosed trailer with a 4 door Polaris General with gear when camping hunting.

My 2016 is beginning to have random quirky issues… had to replace 2 thermostats which was spendy as hell. Now the truck is periodically “clunking” when I almost come to a stop at traffic lights. Ticks me off because I’ve babied this truck. Has around 116k miles on it.

I live in mountainous terrain, so I don’t know if it’s a mistake to go from a 3/4 ton to a a newer 1/2 ton? Should I keep with 3/4?

Is the 3.0 better for not getting stuck when offroad? The 3/4 is a heavy beast.
 
Not sure if you made a decision yet, but I've recently been in a very similar spot. My 2011 duramax (235k mi.) stranded me for the 3rd time on the side of the highway so 3 strikes and you're out.

I really wanted to pull the trigger on the 3.0 and was willing to use airbags and weight distribution hitch to more safely tow my 3 horse trailer, with some big mules and horses in it. Sounds like guys have had good luck towing similar weight trailers as yours and mine, BUT...

While the 3.0 has about the same power and torque as a 2001 duramax 3/4 ton, the payload and tongue weight are huge limiting factors. Tongue weight was something like 900lbs.

If our trailers weigh even 8000lbs and assuming 10-15% tongue weight, that averages to be 1000lbs. Payload is somewhere between 1500-1600 depending on trim. IF maxed tongue weight at 900lbs, that leaves 600lbs for passengers, shell, backpacks, coolers, etc... For comfort on daily and forest roads I really wanted the 1/2 ton as it felt great, but I'm pulling the trigger on the 6.6 gasser 3/4 ton.

I am considering some popular options for softening ride (sulastic shackles, deaver softer leaf springs with airbags, "comfort" torsion bar, etc.) then supplement with bags if towing heavy. Since I'm not towing 10k+ I don't need the full towing capacity of a 3/4 ton, so think I can get away with a little softer set up and still be super safe and comfortable towing.

17" tires will certainly be on my 3/4 ton so can lower tire pressures to 50-60 in daily driving and lower on forest roads.
 
I do not think you need big diesel power to pull under 10,000 pounds, but I also like the way a 3/4 ton truck handles weights approaching 10,000 pounds. Have you considered a 3/4 ton gasser?
 
Max tow capacity I could find was 9500lbs for the 3.0 diesel. I wouldnt want to go near the max of that weight in a 1500 unless the tow distance is very short.

I hardly notice a 9000lb trailer with another ton of weight in the bed of my 3500 duramax. Would much rather be overkill than under. Fuel economy also suffers horribly when towing with a gasser or an under powered truck. Curious how the 1500 would tow 80% of its capacity up some mountains. The 10 speed transmission is great though.
 
Looked into the 3.0 duramax a little. A rear access (whole cab comes off) oil pump drive belt needing 150k mile maintenance was an auto DQ for me.

Shame. An inline 6 smaller diesel would be awesome otherwise.
 
Recently upgraded my 2002 3/4 ton Duramax to a 2024 3500 AT4 Duramax. Both crew cab short beds. 1 ton rides and towed smother than the 3/4 did w/ air bags. Still getting use to how wide the truck feels, and all the electronics screens etc. Great power. Do not care for the tailgate, but might like it more as I get older. First stock truck I ever needed a step ladder to get in my toolbox 🤣🤣.
 
LIK2HNT said:
Recently upgraded my 2002 3/4 ton Duramax to a 2024 3500 AT4 Duramax. Both crew cab short beds. 1 ton rides and towed smother than the 3/4 did w/ air bags. Still getting use to how wide the truck feels, and all the electronics screens etc. Great power. Do not care for the tailgate, but might like it more as I get older. First stock truck I ever needed a step ladder to get in my toolbox 🤣🤣.
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Invest in a B&W Stow & Go hitch if you haven't. You'll get used to and like the multi-use gate.
 
7800 lb trailer i'd stick with the 2500.

Between the heavy diesel engine and offroad suspension you picked the absolute worse version of the truck for towing.

at4_towing.PNG
 
I tow about a 7,000lb (maybe a bit more) boat and have the 2500 Denali diesel. It’s perfect imho. You won’t see me go back to a 1/2 ton. Been there and done that.
 
noharleyyet said:
And it can use 87 octane...
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GM 6.6L L8T Engine Guide - Specs, Performance, Problems

How reliable is GM's L8T engine? Check out the specs of the 6.6L gas engine as well as the common problems and performance potential.
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He has a fleet of trucks and pulls skid steers, dump trailers loaded with top soil, gooseneck with big trees and a lot of other equipment. Initial truck cost is less. Maintenance less. No Def and about the same mileage as a diesel. mtmuley
 
mtmuley said:
He has a fleet of trucks and pulls skid steers, dump trailers loaded with top soil, gooseneck with big trees and a lot of other equipment. Initial truck cost is less. Maintenance less. No Def and about the same mileage as a diesel. mtmuley
Click to expand...
Burns up to a quart of oil per 1,000 miles 😯. Still, can’t argue with the 87 octane burn.
 
MtEngineer said:
Looked into the 3.0 duramax a little. A rear access (whole cab comes off) oil pump drive belt needing 150k mile maintenance was an auto DQ for me.

Shame. An inline 6 smaller diesel would be awesome otherwise.
Click to expand...
Timing belt maintenance is now 200K
 
Has anyone got one in the ZR2 1500. The 3.0 was considerably cheaper then the 6.2 in the ZR2.
 
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