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, eff…
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 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.
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.
The most common questions about engine codes, what they mean, how to find them and how this database works
The GM LLX is a robust and refined engine with proper maintenance. The main concerns are the high-pressure fuel pump (in early units) and potential timing chain wear. Regular oil changes with DEXOS1 Gen 2 oil and addressing any fuel system warnings promptly are essential. With these precautions, the engine can easily reach 200,000+ miles.
The most frequent issues are failure of the high-pressure fuel pump, timing chain tensioner wear (causing noise), carbon buildup on intake valves, and oil leaks from gaskets. These are well-documented in GM service literature and can be managed with proactive maintenance.
The 3.6L LLX V6 is used in several GM full-size SUVs, including the Chevrolet Tahoe (2018-Present), GMC Yukon (2018-Present), and Cadillac Escalade (2018-Present). It is the standard engine for these models.
Minor gains are possible with a performance air intake and ECU tune, yielding perhaps 15-20 additional horsepower. Significant power increases are not practical due to the engine's naturally aspirated design. Its strength is in smooth, reliable power delivery for large SUVs.
Fuel economy is typical for a 3.6L V6 in a large SUV. In a 2020 Chevrolet Tahoe 2WD, expect around 16 mpg (US) in the city and 23 mpg (US) on the highway. Actual figures vary with driving style, vehicle weight, and conditions.
Yes. The GM LLX is an interference engine. If the timing chain were to fail or jump significantly, the pistons and valves will collide, causing severe internal engine damage.
GM mandates the use of DEXOS1 Generation 2 specification oil, typically SAE 5W-30. Using non-DEXOS oil can void the warranty and lead to premature engine wear, particularly of the timing chain system. Change intervals should not exceed 7,500 miles.
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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