The GM LLX is a 3,564 cc, V6 petrol engine produced from 2017 to present. It features an aluminium block and heads, dual overhead camshafts (DOHC), and continuously variable valve timing (CVVT) on both intake and exhaust camshafts. This advanced architecture delivers a broad, flat torque curve and class-leading refinement for GM's full-size trucks and SUVs.
Fitted primarily to the Chevrolet Tahoe, GMC Yukon, and Cadillac Escalade, the LLX was engineered for smooth, effortless power delivery and confident towing capability. Emissions compliance for all production years is achieved through direct fuel injection, precise electronic control, and catalytic converters, meeting US EPA Tier 3 Bin 70 standards.
One documented service concern is premature failure of the high-pressure fuel pump, which can lead to no-start conditions or loss of power. This issue, referenced in GM Service Bulletin PIC-6523, is attributed to internal wear in early production units. GM later revised the pump design for improved durability.
All production years (2017–Present) meet US EPA Tier 3 Bin 70 emissions standards (EPA Engine Family Code GMX-LLX).
The GM LLX is a 3,564 cc V6 petrol engine engineered for full-size SUVs and trucks (2017-Present). It combines a DOHC valvetrain with direct injection and dual CVVT to deliver smooth, responsive power and excellent towing capability. Designed to meet stringent US EPA Tier 3 Bin 70 standards, it offers a compelling blend of luxury, performance, and environmental compliance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,564 cc | |
| Fuel type | Petrol | |
| Configuration | V6, DOHC, 24-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 94.0 mm × 85.8 mm | |
| Power output | 355 hp (265 kW) | |
| Torque | 284 lb-ft (385 Nm) | |
| Fuel system | Gasoline direct injection (GDI) | |
| Emissions standard | US EPA Tier 3 Bin 70 | |
| Compression ratio | 11.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven, with continuously variable intake and exhaust cam timing | |
| Oil type | DEXOS1 Gen 2 (SAE 5W-30) | |
| Dry weight | approx. 375 lbs (170 kg) |
The DOHC dual CVVT and direct injection design provides smooth, linear power ideal for towing and highway cruising but requires strict adherence to 7,500-mile oil change intervals using DEXOS1 Gen 2 oil to prevent chain wear and sludge. Extended oil intervals can accelerate timing chain wear. The direct injection system is prone to intake valve carbon buildup, which GM recommends cleaning every 50,000 miles for optimal performance. GM Service Bulletin PIC-6523 details the updated high-pressure fuel pump for affected vehicles.
Oil Specs: Requires DEXOS1 Gen 2 specification oil (GM Service Manual SM-910). This is mandatory for warranty compliance and engine longevity.
Emissions: Certified under US EPA Tier 3 Bin 70 for all model years (EPA Engine Family GMX-LLX).
Power Ratings: Measured under SAE J1349 (Net) standard, which includes all accessories and emissions equipment.
GM Service Manual SM-910 (Chevrolet Tahoe 2018-2023)
GM Engineering Specification ES-910
GM Service Information Bulletin PIC-6523
US Environmental Protection Agency (EPA) Engine Family Database
SAE International: J1349 Engine Power Certification Standard
The GM LLX was used across GM's full-size SUV platforms with longitudinal mounting. This engine received platform-specific adaptations-different intake manifolds and engine mounts for the Tahoe vs. Escalade-and shares its core architecture with the LGX 3.6L V6. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on a machined pad on the front of the engine block, near the timing cover (GM Service Manual SM-910). The 8th digit of the VIN is 'X' for LLX-equipped vehicles. Visually, the 60-degree V6 configuration with aluminium construction, dual overhead camshafts, and direct fuel injectors mounted centrally in the cylinder head is distinctive. Critical differentiation from the turbocharged LGZ: The LLX is naturally aspirated, while the LGZ has twin turbochargers. Parts are not interchangeable.
The LLX's primary reliability risk is high-pressure fuel pump failure, with elevated incidence in early production or high-mileage vehicles. GM service data indicated a notable number of pump replacements before 80,000 miles, while common owner reports cite timing chain noise as a secondary concern. Infrequent oil changes and use of non-DEXOS oil make chain wear critical.
Analysis derived from GM technical bulletins (2017-Present) and aggregated owner repair data (2019-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about GM LLX.
Comprehensive technical documentation and regulatory references
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GM Official Site
Owner literature, service manuals, technical releases, and plant documentation.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
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