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2023 Chevrolet Silverado 3500 HD

Reliability tier: verified - see /disclosure/

Engine: 6.6L V8 Gas (L8T) (GM Gen V small-block V8, 6.6L)

Direct injection on the Gen V small-block architecture, cast-iron block with aluminum heads, 10.8:1 compression, 401hp/464lb-ft; NO AFM/DFM cylinder deactivation - full V8 at all times (the HD-durability choice; lifter complaints must not inherit the LD 5.3/6.2 AFM pattern).

Applicable failure modes (5)

• Intake-valve carbon buildup (direct injection, no port wash)
• Cooling system wear: water pump, hoses, thermostat (towing duty)
• Direct-injection high-pressure fuel pump / injector failures
• Ignition service wear: spark plugs and coils
• Valvetrain hardware failures: lifters, valves (no AFM - attribution guard)

Applicable parts (14)

• gm-hd-gas-l8t: oil-catch-can-kit (honest catalog gap)
• gm-hd-gas-l8t: coolant (service item)
• gm-hd-gas-l8t: cylinder-head (honest catalog gap)
• gm-hd-gas-l8t: fuel-filter (honest catalog gap)
• gm-hd-gas-l8t: hpfp (honest catalog gap)
• gm-hd-gas-l8t: ignition-coil (honest catalog gap)
• gm-hd-gas-l8t: injector (honest catalog gap)
• gm-hd-gas-l8t: intake-valve-cleaning-service (service item)
• gm-hd-gas-l8t: engine-long-block (honest catalog gap)
• 6.6L L8T Spark Plug (OEM)
• 6.6L L8T Spark Plug Wire (OEM)
• 6.6L L8T Spark Plug Wire Kit (OEM)
• 6.6L L8T Thermostat Kit (OEM)
• 6.6L L8T Water Pump (OEM)

Platform recipes (3)

• Cooling inspection and wear-item service for the 6.6L L8T on a towing HD truck: pressure-test, weep hole, hoses, thermostat (mode fm-l8t-cooling-wear)
• L8T ignition service (mode fm-l8t-ignition): no L8T-specific defect exists - this is conventional Gen V truck hardware on service intervals, and the honest recipe is interval discipline
• Rough idle or hesitation on a high-mileage 6.6L L8T: direct injection leaves the intake valves unwashed - borescope before cleaning, and rule out ignition and injectors (same symptoms) (mode fm-l8t-carbon)