The GMC Sierra 2500HD IV (GMTK2XX) Crew Cab Long Box, equipped with the 6.6-liter Duramax Turbo Diesel V8 engine producing 445 horsepower, represents a significant iteration in GMC’s heavy-duty truck lineage. Produced from 2017 to 2019, this variant occupied a premium position within the Sierra 2500HD lineup, targeting buyers requiring substantial towing and hauling capabilities combined with a degree of refinement. It was part of the fourth generation (GMTK2XX) of the Sierra/Silverado HD platform, known for its increased strength and improved interior compared to its predecessors.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD IV (GMTK2XX) Crew Cab Long Box |
| Type (Engine) | 6.6 Duramax TD V8 (445 Hp) Automatic |
| Start of production | 2017 year |
| End of production | 2019 year |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 7.4 kg/Hp, 135.1 Hp/tonne |
| Weight-to-torque ratio | 2.7 kg/Nm, 374.5 Nm/tonne |
| Power | 445 Hp @ 2800 rpm |
| Power per litre | 67.5 Hp/l |
| Torque | 1234 Nm @ 1600 rpm (910.15 lb.-ft. @ 1600 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | Duramax L5P |
| Engine displacement | 6588 cm3 (402.02 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 | 29.7 l (31.38 US qt | 26.13 UK qt) |
| Kerb Weight | 3295 kg (7264.23 lbs.) |
| Max. weight | 4536 kg (10000.17 lbs.) |
| Max load | 1241 kg (2735.94 lbs.) |
| Trunk (boot) space – maximum | 2162 l (76.35 cu. ft.) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 6577 kg (14499.8 lbs.) |
| Length | 6563 mm (258.39 in.) |
| Width including mirrors | 2045 mm (80.51 in.) |
| Height | 1981 mm (77.99 in.) |
| Wheelbase | 4258 mm (167.64 in.) |
| Front track | 1748 mm (68.82 in.) |
| Rear (Back) track | 1709 mm (67.28 in.) |
| Minimum turning circle (turning diameter) | 17.1 m (56.1 ft.) |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 6 gears, automatic transmission |
| Front suspension | Coil spring, Double wishbone, Transverse stabilizer |
| Rear suspension | Rigid axle suspension, Leaf spring |
| Front brakes | Ventilated discs, 350×40 mm |
| Rear brakes | Ventilated discs, 360×34 mm |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Cone worm with recirculation balls |
| Tires size | 235/80 R17; 265/70 R18; 265/60 R20 |
| Wheel rims size | 7.5J x 17; 8J x 18; 8.5J x 20 |
INTRODUCTION
The 2017-2019 GMC Sierra 2500HD Crew Cab Long Box with the 6.6L Duramax diesel and automatic transmission was positioned as a workhorse for serious towing and hauling. Built on the GMTK2XX platform, it offered a significant upgrade in capability and refinement over previous generations. The Crew Cab configuration provided ample passenger space, while the Long Box maximized cargo capacity. This particular configuration was aimed at buyers who needed a powerful truck for both professional and personal use, such as those involved in construction, agriculture, or recreational activities like towing large trailers or boats.
Powertrain & Engine Architecture
At the heart of this Sierra 2500HD lies the Duramax L5P 6.6-liter turbocharged diesel V8. This engine is a testament to modern diesel technology, featuring a cast iron block, aluminum cylinder heads, and a robust rotating assembly. The L5P utilizes a Bosch common rail fuel injection system, capable of delivering extremely high injection pressures for optimized combustion. The engine also incorporates a variable geometry turbocharger (VGT) and an intercooler to maximize power and efficiency. The overhead valve (OHV) valvetrain, while seemingly traditional, is known for its durability and reliability. The six-speed Allison automatic transmission (model 1000) is specifically designed to handle the immense torque output of the Duramax engine. This transmission features electronically controlled shifts and a lock-up torque converter for improved fuel economy and responsiveness.
Driving Characteristics
The combination of the 445 horsepower and 910 lb-ft of torque delivered by the Duramax engine and Allison transmission results in impressive performance. While not a sports truck, the Sierra 2500HD offers strong acceleration, even when heavily loaded. The Allison transmission is well-tuned, providing smooth and predictable shifts. The gear ratios are optimized for towing, allowing the truck to maintain speed and control even on steep grades. Compared to the gasoline-powered versions of the Sierra 2500HD, the Duramax diesel offers significantly more low-end torque, making it ideal for hauling heavy loads. Compared to manual transmission equipped Duramax models, the automatic provides ease of use, particularly in stop-and-go traffic or when navigating challenging terrain. However, some drivers may prefer the greater control offered by a manual transmission.
Equipment & Trim Levels
The Sierra 2500HD offered a range of trim levels, with the Duramax/automatic combination typically found in the SLT, AT4, and Denali trims. Standard features on these trims included a rearview camera, an 8-inch touchscreen infotainment system with Apple CarPlay and Android Auto compatibility, and a premium audio system. Higher trims added features such as leather upholstery, heated and ventilated front seats, a power-adjustable steering column, and advanced safety technologies like lane departure warning and forward collision alert. Optional extras included a sunroof, a navigation system, and a rear-seat entertainment system.
Chassis & Braking
The GMTK2XX platform features a fully boxed frame constructed from high-strength steel, providing a solid foundation for the truck. The front suspension utilizes coil springs and a double wishbone design, while the rear suspension employs leaf springs. This configuration is designed to handle heavy loads and provide a comfortable ride. Braking duties are handled by ventilated disc brakes on all four wheels. The front brakes measure 350x40mm, while the rear brakes are 360x34mm. An Anti-lock Braking System (ABS) is standard. The steering system utilizes a cone worm with recirculation balls, providing precise and responsive steering feel.
Market Reception & Comparison
The 2017-2019 GMC Sierra 2500HD with the Duramax diesel and automatic transmission was generally well-received by critics and consumers alike. It was praised for its powerful engine, smooth transmission, and comfortable ride. Fuel economy, while not exceptional, was considered reasonable for a heavy-duty truck. Compared to the gasoline-powered Sierra 2500HD, the Duramax diesel offered superior towing and hauling capabilities, as well as better fuel economy when towing. Compared to competitors like the Ford Super Duty and Ram 2500, the Sierra 2500HD was often seen as offering a good balance of capability, comfort, and refinement.
Legacy
The Duramax L5P engine and Allison 1000 transmission have proven to be exceptionally reliable powertrains. Properly maintained, these components can easily exceed 200,000 miles. On the used car market, the 2017-2019 Sierra 2500HD with the Duramax diesel commands a premium price due to its reputation for durability and capability. These trucks remain popular among buyers who need a powerful and reliable workhorse for demanding tasks. The GMTK2XX platform laid the groundwork for future generations of GMC heavy-duty trucks, continuing the brand’s legacy of building tough and capable vehicles.
