The GMC Sierra 3500HD III, specifically the Crew Cab Long Box configuration with the 6.6-liter Duramax Turbo Diesel V8 engine and four-wheel drive, represents a significant iteration in GMC’s heavy-duty truck lineage. Produced from 2011 to 2013 as part of the GMT900 platform’s facelift, this variant was designed to cater to owners requiring substantial towing and hauling capabilities combined with a degree of passenger comfort. It occupied the upper echelon of the Sierra 3500HD lineup, positioned as a premium offering for those needing maximum performance and utility. This model year saw refinements to the interior and exterior styling, along with improvements to the already robust Duramax engine.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD III (GMT900, facelift 2011) Crew Cab Long Box |
| Type (Engine) | 6.6 Duramax TD V8 (397 Hp) 4WD DRW Automatic |
| Start of production | 2011 |
| End of production | 2013 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 9.1 kg/Hp, 109.5 Hp/tonne |
| Weight-to-torque ratio | 3.5 kg/Nm, 285.9 Nm/tonne |
| Power | 397 Hp @ 3000 rpm |
| Power per litre | 60.2 Hp/l |
| Torque | 1037 Nm @ 1600 rpm (764.85 lb.-ft. @ 1600 rpm) |
| Maximum engine speed | 3000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | Duramax LML |
| Engine displacement | 6599 cm3 (402.7 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 103 mm (4.06 in.) |
| Piston Stroke | 99 mm (3.9 in.) |
| Compression ratio | 16:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Turbocharger, Intercooler |
| Valvetrain | OHV |
| Engine oil capacity | 9.5 l (10.04 US qt | 8.36 UK qt) |
| Coolant | 24 l (25.36 US qt | 21.12 UK qt) |
| Kerb Weight | 3627 kg (7996.17 lbs.) |
| Max. weight | 5908 kg (13024.91 lbs.) |
| Max load | 2281 kg (5028.74 lbs.) |
| Trunk (boot) space – maximum | 2138 l (75.5 cu. ft.) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 8165 kg (18000.74 lbs.) |
| Length | 6581 mm (259.09 in.) |
| Width including mirrors | 2436 mm (95.91 in.) |
| Height | 1979 mm (77.91 in.) |
| Wheelbase | 4260 mm (167.72 in.) |
| Front track | 1748 mm (68.82 in.) |
| Rear (Back) track | 1906 mm (75.04 in.) |
| Ride height (ground clearance) | 213 mm (8.39 in.) |
| Minimum turning circle (turning diameter) | 16.9 m (55.45 ft.) |
| Drivetrain Architecture | All wheel drive (4×4). ICE drives rear wheels, front wheels engaged via clutch. |
| Number of gears and type of gearbox | 6 gears, automatic transmission Allison |
| Front suspension | Independent torsion bar, double wishbone |
| Rear suspension | Rigid axle suspension, Leaf spring |
| Front brakes | Ventilated discs, 355×40 mm |
| Rear brakes | Ventilated discs, 373×34 mm |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Cone worm with recirculation balls |
| Tires size | 235/80 R17; 265/70 R18 |
INTRODUCTION
The 2011-2013 GMC Sierra 3500HD Crew Cab Long Box, powered by the 6.6L Duramax diesel and paired with the Allison automatic transmission, was a workhorse designed for serious tasks. Built on the GMT900 platform, this generation represented a significant step forward in heavy-duty truck refinement. The facelift introduced in 2011 brought updated styling, improved interior materials, and enhanced functionality. The Crew Cab configuration offered spacious seating for five passengers, making it suitable for both work and family use, while the Long Box provided ample cargo space. The dual rear wheel (DRW) setup further enhanced its towing and hauling capabilities, making it a popular choice for commercial applications and owners with large trailers.
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD lies the Duramax LML 6.6-liter turbocharged diesel V8 engine. This engine is a testament to diesel engineering, featuring a cast iron block, aluminum cylinder heads, and a robust crankshaft. The LML iteration of the Duramax introduced a revised combustion chamber and improved fuel injection system for increased efficiency and reduced emissions. The engine utilizes a common-rail direct injection system, delivering fuel at extremely high pressures for optimal combustion. The turbocharger, coupled with an intercooler, provides increased air intake, boosting power and torque. The overhead valve (OHV) valvetrain is known for its durability and simplicity. The Allison 1000 six-speed automatic transmission is specifically designed to handle the immense torque output of the Duramax engine. This transmission features a lock-up torque converter for improved fuel economy and a heavy-duty cooling system to prevent overheating under demanding conditions.
Driving Characteristics
The combination of the 397 horsepower and 765 lb-ft of torque delivered by the Duramax engine and the Allison transmission results in a driving experience focused on capability rather than outright speed. Acceleration is brisk, especially considering the truck’s substantial weight. The Allison transmission shifts smoothly and decisively, providing ample power for towing and hauling. The gear ratios are optimized for low-end torque, making it easy to pull heavy loads from a standstill. Compared to gasoline-powered Sierra 3500HD models, the diesel offers significantly more torque, making it far more capable for demanding tasks. While the manual transmission versions offered a more engaging driving experience, the automatic provided convenience and ease of use, particularly in stop-and-go traffic. The DRW configuration enhances stability when towing, reducing sway and improving overall control.
Equipment & Trim Levels
The Crew Cab Long Box 3500HD typically came standard with features like air conditioning, power windows and locks, a tilt steering wheel, and a basic audio system. Higher trim levels, such as the SLT and Denali, added features like leather upholstery, heated and cooled front seats, a premium audio system, navigation, and a rear vision camera. Optional extras included a sunroof, upgraded wheels, and various towing packages. The interior design was functional and durable, with a focus on providing a comfortable and practical environment for both work and passenger use. The dashboard layout was straightforward, with easy-to-read gauges and intuitive controls.
Chassis & Braking
The Sierra 3500HD’s chassis is built for heavy-duty use, featuring a fully boxed frame and robust suspension components. The front suspension utilizes an independent torsion bar setup with double wishbones, providing a comfortable ride and good handling. The rear suspension employs a rigid axle with leaf springs, designed to handle heavy loads. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power. An Anti-lock Braking System (ABS) is standard, enhancing safety and control during emergency braking situations. The DRW configuration provides increased stability and braking performance when towing heavy loads.
Market Reception & Comparison
The 2011-2013 GMC Sierra 3500HD with the Duramax diesel and Allison automatic received generally positive reviews. Critics praised its powerful engine, smooth transmission, and impressive towing and hauling capabilities. Fuel economy, while not exceptional, was considered reasonable for a heavy-duty truck. Compared to the 6.0L gasoline V8 versions, the Duramax offered significantly more torque and better fuel economy when towing. The 1.9 TDI versions of comparable European trucks offered better fuel economy but lacked the sheer towing capacity of the Sierra 3500HD. Reliability was generally good, although some owners reported issues with the diesel particulate filter (DPF) system.
Legacy
The Duramax LML engine and Allison transmission combination has proven to be exceptionally durable and reliable. These trucks continue to hold their value well in the used car market, particularly those that have been well-maintained. The 2011-2013 Sierra 3500HD remains a popular choice for owners who need a capable and dependable heavy-duty truck. The LML Duramax engine is considered one of the most reliable diesel engines ever produced, and the Allison transmission is renowned for its durability and smooth operation. These trucks represent a sweet spot in the heavy-duty truck market, offering a balance of power, capability, and reliability.
