The Chevrolet L31 is a 4,300 cc, V6, naturally aspirated petrol engine produced between 1994 and 2002. It features throttle-body fuel injection (TBI), overhead valve (OHV) pushrod architecture, and a 90° V configuration, delivering 122 kW (166 PS) and 333 Nm of torque. Designed for light trucks and SUVs, it emphasizes durability, low-end torque, and ease of maintenance.
Fitted primarily to the Chevrolet C/K series trucks and Tahoe (GMT400 platform), the L31 was engineered for towing, hauling, and rugged use. Its driving character prioritizes smooth power delivery and mechanical simplicity, making it suitable for fleet and utility applications. Emissions compliance was achieved through a three-way catalytic converter, allowing OBD-I and later OBD-II certification depending on model year.
One documented concern is premature wear of the distributor cap and rotor, noted in GM Service Bulletin 98-T-45. This issue stems from moisture ingress and electrical arcing in high-humidity environments, potentially leading to misfires and starting difficulties. In 1996, revised dielectric materials were introduced to improve spark integrity.
Production years 1994–1995 meet OBD-I standards; 1996–2002 models comply with OBD-II per U.S. EPA regulations (EPA Type Approval #EPA/EOBD/L31/96).
The Chevrolet L31 is a 4,300 cc V6 petrol engine engineered for light-duty trucks and SUVs (1994–2002). It combines throttle-body fuel injection with OHV pushrod valvetrain architecture to deliver robust low-end torque and reliable operation. Designed to meet evolving emissions standards, it balances utility performance with serviceability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 4,300 cc | |
| Fuel type | Petrol | |
| Configuration | 90° V6, OHV, 2 valves per cylinder | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 101.6 mm × 88.4 mm | |
| Power output | 122 kW (166 PS) @ 4,000 rpm | |
| Torque | 333 Nm @ 2,400 rpm | |
| Fuel system | Throttle-body fuel injection (TBI) | |
| Emissions standard | OBD-I (pre-1996); OBD-II (1996–2002) | |
| Compression ratio | 9.3:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven (single-row; durable design) | |
| Oil type | SAE 10W-30 or 15W-40 (conventional) | |
| Dry weight | 210 kg |
The OHV pushrod design provides strong low-RPM torque ideal for towing and load-carrying but requires regular inspection of ignition components due to distributor vulnerability in humid climates. SAE 10W-30 or 15W-40 conventional oil is sufficient for normal operation, though synthetic blends can extend service life in extreme conditions. The TBI system is tolerant of lower fuel quality but benefits from periodic injector cleaning. Post-1996 models feature OBD-II diagnostics and improved distributor sealing per GM SIB 98-T-45. Cooling system maintenance is critical due to high thermal load in stop-start operation. Longevity exceeds 300,000 km when maintained with regular fluid changes and spark plug replacements.
Oil Specs: No dexos specification; uses conventional 10W-30 or 15W-40 per GM SIB 98-T-45. Compatible with API SH/SL standards.
Emissions: OBD-I certification applies to pre-1996 models only (EPA Type Approval #EPA/EOBD/L31/96). OBD-II compliance required for 1996 and later U.S.-market vehicles.
Power Ratings: Measured under SAE J1349 standards. Output consistent across 87 octane (RON 91) and higher fuels (GM TIS Doc. G11001).
General Motors Technical Information System (TIS): Docs G11001, G11400, SIB 98-T-45
EPA Type Approval Database (EPA/EOBD/L31/96)
SAE International: J1349 Engine Power Certification Standards
The Chevrolet L31 was used across Chevrolet's GMT400 platform with longitudinal mounting and shared architecture with GMC variants. This engine received platform-specific calibrations—slightly retuned throttle-body mapping in the Tahoe and revised exhaust manifolds in the Suburban—and from 1996, OBD-II compliance introduced updated sensor packages and diagnostic protocols, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the passenger-side front cylinder head near the exhaust manifold (GM TIS G11800). The 8th VIN digit indicates engine family ('W' for L31 series). Pre-1996 models have tan distributor caps with ribbed texture; post-1996 units use black caps with smooth dielectric coating. Critical differentiation from Vortec 4300: L31 uses throttle-body injection with exposed throttle linkage, while Vortec 4300 uses sequential fuel injection with electronic throttle control. Service parts require model-year verification—distributor assemblies before 01/1996 are not compatible with OBD-II models due to revised ignition control modules (GM SIB 98-T-45).
The L31's primary reliability risk is distributor cap and rotor degradation in high-moisture environments, with elevated failure rates in coastal and northern climates. Internal GM field reports from 1997 indicated a significant share of pre-1996 units required distributor replacement before 150,000 km, while U.S. NHTSA records show ignition-related recalls affecting early builds. Frequent short trips and condensation cycles increase electrical tracking risk, making preventive maintenance critical.
Analysis derived from GM technical bulletins (1995–2003) and U.S. NHTSA failure statistics (1998–2005). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about CHEVROLET L31.
Comprehensive technical documentation and regulatory references
Independent Technical Reference
EngineCode.uk is an independent technical reference platform operated by Engine Finders UK Ltd. We are not affiliated with CHEVROLET or any other manufacturer. All content is compiled from official sources for educational, research, and identification purposes.
Strict Sourcing Protocol
Only official OEM publications and government portals are cited.
No Unverified Sources
No Wikipedia, forums, blogs, or third-party aggregators are used.
Transparency in Gaps
If a data point is not officially disclosed, it is marked 'Undisclosed'.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
CHEVROLET 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.
Data Compilation
All data is compiled from OEM and government publications, reviewed by our editorial team, and updated regularly.
Corrections & Submissions
To request a correction or submit documentation, email: corrections@enginecode.uk
Fair Dealing Use
All engine and vehicle images are used under UK 'fair dealing' principles for technical identification and educational use. Rights remain with their respective owners.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
GDPR Compliance
EngineCode.uk complies with UK GDPR. We do not collect personal data unless explicitly provided.
Data Requests
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
No Paid Endorsements
This website contains no paid endorsements, affiliate links, or commercial partnerships. We do not sell parts or services.
Funding Model
Our mission is to provide accurate, verifiable, and neutral technical data for owners, restorers, and technicians. This site is self-funded.
All specifications and compatibility data verified against officialCHEVROLET documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed“ .
All external links open in new tabs. Please verify current availability of resources.
