2017–2019 Chevy Silverado / GMC Sierra 2500/3500 HD 6.6L Duramax L5P Extruded Tube Aluminum Radiator

2017–2019 Chevy Silverado / GMC Sierra 2500/3500 HD 6.6L Duramax L5P Extruded Tube Aluminum Radiator

The 2017 model year brought the L5P Duramax, and with it a major jump to 445 horsepower and 910 lb-ft of torque from the factory. GM had to rework the entire cooling system to keep up, and for good reason: the L5P makes more heat than any Duramax before it, and the 2017 through 2019 Silverado and Sierra HD trucks carry that engine in the final years of the previous-generation body before the 2020 redesign. These trucks tow hard, work hard, and are frequently tuned, and the factory plastic-tank radiator is the weak link standing between that engine and its operating temperature. Fluidyne built this radiator to remove that weak link.

The core is where this radiator separates itself. Instead of the thin, stamped-and-folded tubes found in most aftermarket radiators, Fluidyne uses true extruded aluminum tubes, formed as a single continuous piece with a heavier wall section and no seams to split under pressure or vibration. Extruded tubes hold their shape under the heat cycling and chassis flex that come with heavy towing and sustained high load, and the increased wall thickness gives the core a durability margin that folded tubes cannot match. The result is a core that keeps the L5P at temperature whether it is pulling a fifth wheel through the mountains or making tuned power well beyond the factory rating.

The tanks are fabricated from thick-gauge aluminum sheet rather than the plastic found on the factory unit, and every tank seam, inlet, outlet, and fitting is hand TIG welded. TIG welding produces a deep, controlled penetration weld with a clean bead that resists fatigue cracking where plastic tanks, crimped seams, and cheaper welded assemblies eventually fail. This is the same fabrication standard found on purpose-built race cooling, applied to a truck that is expected to work for hundreds of thousands of miles.

Engine temperature is only half of the equation. The Allison 1000 behind the L5P generates its own heat under load, and on these trucks that heat is shed through the same front-end airflow the radiator depends on. A transmission running hot raises the temperature of everything around it, cooks fluid, and shortens the life of clutches and the torque converter. To get the most out of this radiator and fully optimize the cooling system, pair it with the Fluidyne transmission cooler for the 2017–2019 Duramax. Built with the same construction standards, the two work together as a complete system to keep both the engine and transmission at temperature under the hardest towing and highest power levels.

Fitment is engineered as a direct replacement for the factory radiator in both the Chevy Silverado HD and GMC Sierra HD, using the original mounting points, hose connections, and shroud location with no cutting, drilling, or modification required.