The GM LA1 is a 3,350 cc, 60‑degree V6 petrol engine produced between 1996 and 2005. It features a cast iron block, aluminum heads, sequential fuel injection, and an overhead valve (OHV) design. This “3400” engine delivered 180–200 hp and 205–220 lb‑ft of torque, with its simple pushrod layout enabling a compact package ideal for transverse mounting.
Fitted to models such as the Chevrolet Lumina, Pontiac Grand Prix, and Buick Century, the LA1 was engineered for smooth, reliable transportation with an emphasis on low‑end torque and everyday drivability. Emissions compliance was achieved through electronic throttle control and catalytic converters, meeting U.S. Tier 1 and later Tier 2 standards.
One documented concern is upper intake manifold cracking, which can lead to coolant leaks into the combustion chamber or externally. This issue, highlighted in GM Service Bulletin 03‑06‑01‑010B, is often linked to material fatigue and thermal cycling. Around 2003, GM introduced a revised, more robust intake manifold design.
Production years 1996–2002 meet U.S. Tier 1 standards; 2003–2005 models meet Tier 2 Bin 5 standards (EPA Engine Family Code: 3GAXV03.4LBAK).
The GM LA1 is a 3,350 cc 60-degree V6 petrol engine engineered for mid-size sedans and coupes (1996-2005). It combines sequential multi-port fuel injection with an overhead valve (pushrod) design to deliver strong low-end torque and smooth, reliable performance. Designed to meet U.S. Tier 1 and Tier 2 emissions standards, it prioritizes durability and serviceability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,350 cc | |
| Fuel type | Petrol (Gasoline) | |
| Configuration | 60° V6, OHV, 2 valves per cylinder | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 92.0 mm × 84.0 mm | |
| Power output | 180–200 hp (134–149 kW) | |
| Torque | 205–220 lb-ft (278–298 Nm) | |
| Fuel system | Sequential multi-port fuel injection (SFI) | |
| Emissions standard | U.S. Tier 1 (1996-2002); U.S. Tier 2 Bin 5 (2003-2005) | |
| Compression ratio | 9.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven camshaft | |
| Oil type | SAE 5W-30 API SJ/SL | |
| Dry weight | 375 lb (170 kg) |
The OHV design provides robust low-RPM torque and a compact size but requires vigilance for the known upper intake manifold failure. Using Dex-Cool coolant is critical, as mixing coolant types can accelerate manifold degradation. The timing chain is generally reliable for 150,000+ miles with proper oil changes. Spark plug replacement is straightforward due to the overhead valve layout. Post-2003 models feature the updated, more durable intake manifold per GM bulletin 03-06-01-010B.
Oil Specs: Requires SAE 5W-30 meeting API SJ/SL specification (GM Owner's Manual). Dexos1 Gen 2 is a suitable modern equivalent.
Emissions: Tier 1 certification applies to 1996-2002 models (EPA 3GAXV03.4LBAK). Tier 2 Bin 5 applies to 2003-2005 models.
Power Ratings: Measured under SAE J1349 standards. Output varies by model year and application (GM Powertrain Manual PTM-3400-96).
GM Technical Service Bulletins: 03-06-01-010B
GM Service Manual SM-3400-01
U.S. Environmental Protection Agency (EPA) Engine Certification Database
SAE International: J1349 Engine Power Certification Standards
The GM LA1 was used across GM's W-body and N-body platforms with transverse mounting and no external licensing. This engine received platform-specific adaptations-different accessory brackets for the Grand Prix versus the Lumina-and from 2003 the intake manifold was revised for improved durability, creating a key interchange difference. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on a flat pad on the front of the engine block, just below the right (passenger side) cylinder head (GM TIS 3400-001). The 8th digit of the VIN is 'E' for vehicles equipped with the LA1 engine. Pre-2003 engines have a black plastic upper intake manifold prone to cracking; post-2003 units have a revised, more robust design. Critical differentiation from the similar L82 3.8L: The LA1 is a 3.4L (casting number 10223666) while the L82 is a 3.8L (casting number 12552459).
The LA1's primary reliability risk is upper intake manifold failure, with elevated incidence in high-mileage vehicles. GM internal data indicated a significant failure rate for pre-2003 manifolds, while owner forums consistently report coolant leaks as the most common issue. Extended service intervals and improper coolant use make the updated manifold and correct fluid critical.
Analysis derived from GM technical bulletins (2000-2005) and NHTSA complaint data (2000-2010). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about GM LA1.
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GOV.UK: Vehicle Approval & V5C
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
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