The GMC Sierra 2500HD IV (GMTK2XX) Crew Cab Standard Box, equipped with the 6.6-liter Duramax Turbo Diesel V8 engine producing 445 horsepower and paired with a 6-speed Allison automatic transmission and four-wheel drive, represents a significant iteration in GMC’s heavy-duty truck lineage. Produced from 2017 to 2019, this configuration occupied a premium position within the Sierra 2500HD lineup, targeting buyers needing substantial towing and hauling capacity without sacrificing comfort or refinement. It was part of the fourth generation of the Sierra HD series, known as the GMTK2XX platform, which brought enhanced capability and technology to the heavy-duty truck segment.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD IV (GMTK2XX) Crew Cab Standard Box |
| Type (Engine) | 6.6 Duramax TD V8 (445 Hp) 4WD Automatic |
| Start of production | 2017 |
| End of production | 2019 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 7.6 kg/Hp, 131.5 Hp/tonne |
| Weight-to-torque ratio | 2.7 kg/Nm, 364.5 Nm/tonne |
| Power | 445 Hp @ 2800 rpm |
| Power per litre | 67.4 Hp/l |
| Torque | 1234 Nm @ 1600 rpm (910.15 lb.-ft. @ 1600 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | Duramax L5P |
| Engine displacement | 6604 cm3 (403 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 | 3385 kg (7462.65 lbs.) |
| Max. weight | 4536 kg (10000.17 lbs.) |
| Max load | 1151 kg (2537.52 lbs.) |
| Trunk (boot) space – maximum | 1728 l (61.02 cu. ft.) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 5897 kg (13000.66 lbs.) |
| Length | 6083 mm (239.49 in.) |
| Width including mirrors | 2045 mm (80.51 in.) |
| Height | 1987 mm (78.23 in.) |
| Wheelbase | 3904 mm (153.7 in.) |
| Front track | 1748 mm (68.82 in.) |
| Rear (Back) track | 1709 mm (67.28 in.) |
| Minimum turning circle (turning diameter) | 15.7 m (51.51 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 | 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; 275/65 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 with the 6.6L Duramax diesel and Allison automatic was a cornerstone of GMC’s professional-grade truck marketing. Built on the GMTK2XX platform, it offered a compelling blend of power, capability, and interior comfort. The Crew Cab configuration provided ample passenger space, making it suitable for both work and family use, while the standard box offered a practical cargo bed length. This variant was positioned as a premium offering, appealing to customers who frequently tow large trailers, haul heavy loads, or require a robust and reliable work truck.
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, delivering fuel at extremely high pressures for optimized combustion and efficiency. The turbocharger, coupled with an intercooler, provides increased air intake, boosting power and torque. The engine’s valvetrain employs an overhead valve (OHV) configuration, known for its durability and simplicity. The Allison 1000 Series 6-speed automatic transmission is specifically designed to handle the immense torque output of the Duramax engine. It features electronically controlled shifts and a lock-up torque converter for improved fuel economy and responsiveness. The transmission’s robust construction ensures reliable operation even under demanding conditions.
Driving Characteristics
The 445 horsepower and 910 lb-ft of torque delivered by the Duramax/Allison combination translate into impressive real-world performance. Acceleration, while not sporty, is strong and confident, even with a heavy load. The Allison transmission provides smooth and precise shifts, and the gear ratios are well-suited for both towing and everyday driving. Compared to the gasoline-powered 6.0L V8 option, the Duramax offers significantly more torque at lower RPMs, making it ideal for towing. While a 6-speed automatic isn’t as modern as some 8 or 10-speed transmissions found in newer trucks, it’s known for its durability and reliability. The 4WD system provides excellent traction in various conditions, enhancing stability and control.
Equipment & Trim Levels
The Sierra 2500HD Crew Cab with the Duramax engine typically came well-equipped, even in its base trim. Standard features included air conditioning, power windows and locks, a rearview camera, and a basic infotainment system. Higher trim levels, such as the SLT and Denali, added features like leather upholstery, heated and ventilated seats, a premium sound system, navigation, and advanced safety technologies. Optional extras included a sunroof, a spray-in bedliner, and various towing packages. The interior design focused on functionality and durability, with comfortable seating and intuitive controls.
Chassis & Braking
The Sierra 2500HD’s chassis is built for heavy-duty use, featuring a fully boxed frame and robust suspension components. The front suspension utilizes coil springs and a double wishbone design, while the rear suspension employs leaf springs. This configuration provides a comfortable ride while maintaining excellent load-carrying capacity. The braking system consists of ventilated discs 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 rear axle ratios varied depending on the specific configuration, influencing both towing capacity and fuel economy.
Market Reception & Comparison
The GMC Sierra 2500HD with the Duramax diesel engine consistently received positive reviews from automotive critics. It was praised for its powerful engine, smooth transmission, comfortable ride, and impressive towing capacity. Compared to the gasoline-powered Sierra 2500HD, the Duramax offered superior fuel economy when towing heavy loads. However, the Duramax engine and Allison transmission came at a significant price premium. Compared to competitors like the Ford Super Duty and Ram 2500, the Sierra 2500HD was often seen as offering a more refined interior and a smoother ride.
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 GMC Sierra 2500HD with the Duramax diesel commands a premium price due to its reputation for durability and capability. These trucks remain highly sought after by buyers who need a powerful and reliable work truck or a capable towing vehicle. The GMTK2XX platform, while superseded by newer generations, remains a solid and dependable foundation for a heavy-duty truck.
