The GMC Sierra 3500HD IV (GMTK2XX) Crew Cab Standard Box, equipped with the 6.6-liter Duramax Turbo Diesel V8 engine producing 397 horsepower and paired with an Allison automatic transmission, represents a significant iteration in GMC’s heavy-duty truck lineage. Produced from 2015 to 2017, this variant occupied a premium position within the Sierra 3500HD lineup, targeting buyers requiring substantial towing and hauling capabilities combined with a degree of comfort and refinement. It was part of the fourth generation of the Sierra/Silverado HD trucks, known as the GMTK2XX platform, which brought substantial improvements in capability, interior space, and technology.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD IV (GMTK2XX) Crew Cab Standard Box |
| Type (Engine) | 6.6 Duramax TD V8 (397 Hp) SRW Automatic |
| Start of production | 2015 |
| End of production | 2017 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 8.1 kg/Hp, 123.4 Hp/tonne |
| Weight-to-torque ratio | 3.1 kg/Nm, 322.2 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) |
| 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 | 22.4 l (23.67 US qt | 19.71 UK qt) |
| Kerb Weight | 3218 kg (7094.48 lbs.) |
| Max. weight | 5035 kg (11100.27 lbs.) |
| Max load | 1817 kg (4005.8 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 | 1990 mm (78.35 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) | 15.8 m (51.84 ft.) |
| Drivetrain Architecture | Rear wheel drive |
| 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, 355×40 mm |
| Rear brakes | Ventilated discs, 373×34 mm |
| Tires size | 235/80 R17; 265/70 R18 |
| Wheel rims size | 7.5J x 17; 8J x 18 |
INTRODUCTION
The 2015-2017 GMC Sierra 3500HD Crew Cab with the 6.6L Duramax diesel and Allison automatic transmission was a cornerstone of GMC’s heavy-duty truck offerings. Built on the GMTK2XX platform, it represented a move towards increased refinement and capability. The “3500HD” designation signifies its status as a heavy-duty truck, designed for demanding tasks like commercial hauling and substantial recreational towing. The Crew Cab configuration provided ample passenger space, making it suitable for both work and family use. This particular variant, with its potent diesel engine and smooth-shifting automatic, was positioned as a premium option for buyers who didn’t want to compromise on power or comfort.
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD lies the Duramax LML 6.6-liter turbocharged diesel V8. This engine is renowned for its durability and torque output. The LML iteration of the Duramax introduced a revised turbocharger, improved fuel injection system, and enhanced exhaust gas recirculation (EGR) system to meet stricter emissions standards. The engine utilizes a common-rail direct fuel injection system, delivering fuel at extremely high pressure for optimal combustion. The overhead valve (OHV) valvetrain, while seemingly traditional, is robust and well-suited to the demands of a heavy-duty diesel. The Allison 1000 Series 6-speed automatic transmission is a critical component, specifically engineered to handle the immense torque produced by the Duramax engine. This transmission features a lock-up torque converter for improved efficiency and a heavy-duty cooling system to prevent overheating under strenuous conditions.
Driving Characteristics
The combination of the 397 horsepower and 765 lb-ft of torque delivered a commanding driving experience. While not as overtly quick as some gasoline-powered trucks, the Duramax provided a broad, flat torque curve, making it exceptionally capable for towing and hauling. The Allison transmission shifted smoothly and predictably, contributing to a comfortable ride even when heavily loaded. Compared to the 6.0L gasoline V8 option, the Duramax offered significantly more torque and better fuel economy, especially under load. Compared to the 3500HD models equipped with the manual transmission, the automatic provided greater convenience, particularly in stop-and-go traffic. However, some drivers preferred the more direct feel and control offered by the manual gearbox. The gear ratios in the Allison transmission were optimized for both towing and highway cruising, providing ample power for climbing hills and maintaining speed on the open road.
Equipment & Trim Levels
The Sierra 3500HD 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 basic audio system, and a rearview camera. Higher trim levels, such as the SLT and Denali, added features like leather upholstery, heated and ventilated front seats, a premium audio system, navigation, and advanced safety technologies. Optional extras included a sunroof, upgraded wheels, and various towing packages. The interior design focused on functionality and durability, with comfortable seating and easy-to-use controls. The Crew Cab configuration offered generous rear seat legroom, making it a practical choice for families.
Chassis & Braking
The Sierra 3500HD’s chassis was designed to withstand the stresses of heavy-duty use. It featured a fully boxed frame constructed from high-strength steel. The front suspension utilized coil springs and a double wishbone design, while the rear suspension employed leaf springs. This configuration provided a comfortable ride while maintaining excellent load-carrying capacity. Braking duties were handled by ventilated disc brakes on all four wheels. The front brakes measured 355x40mm, while the rear brakes were 373x34mm. An Anti-lock Braking System (ABS) was standard, enhancing safety during emergency braking situations. The rear axle was a solid axle, providing robust strength for hauling heavy loads.
Market Reception & Comparison
The GMC Sierra 3500HD with the Duramax diesel and Allison automatic received generally positive reviews from automotive critics. It was praised for its powerful engine, smooth transmission, comfortable ride, and impressive towing capacity. Fuel economy was considered good for a heavy-duty truck, although it still lagged behind lighter-duty pickups. Compared to the Ford Super Duty and Ram 3500, the Sierra 3500HD was often seen as offering a more refined interior and a smoother ride. However, some critics noted that the GMC’s price was higher than its competitors. Reliability was generally good, although some owners reported issues with the EGR system and diesel particulate filter.
Legacy
The Duramax LML engine and Allison transmission pairing in the 2015-2017 GMC Sierra 3500HD has proven to be a durable and reliable powertrain. These trucks continue to hold their value well in the used car market, particularly those that have been well-maintained. The LML Duramax is known for its longevity and relatively low maintenance costs. While modern heavy-duty trucks offer even more power and technology, the GMTK2XX Sierra 3500HD remains a capable and dependable workhorse, appealing to buyers seeking a proven and robust truck for demanding tasks. The combination of power, comfort, and reliability has cemented its place as a popular choice among truck enthusiasts and professionals alike.
