The GM LH8 is a 5,328 cc, 90‑degree V8 petrol engine produced between 2008 and 2012. It features a cast iron block, aluminum heads, and overhead valve (OHV) pushrod architecture with variable valve timing (VVT) on the exhaust cam. This Vortec engine delivered 300 hp and 320 lb‑ft of torque, emphasizing low-end grunt and towing capability for truck applications.
Fitted to models such as the Hummer H3 Alpha and Chevrolet Colorado/GMC Canyon (in certain markets), the LH8 was engineered for rugged, off-road and utility use with an emphasis on durability and torque. Emissions compliance was achieved through electronic throttle control and catalytic converters, meeting U.S. Tier 2 Bin 5 standards.
One documented concern is premature failure of the exhaust camshaft variable valve timing actuator, which can lead to reduced performance and check engine light illumination. This issue, highlighted in GM Service Bulletin 10‑06‑01‑003, is often linked to oil flow restrictions or actuator solenoid wear. GM later revised the actuator design for improved reliability.
All production years (2008–2012) meet U.S. Tier 2 Bin 5 standards (EPA Engine Family Code: 3GAXV05.3LBAK).
The GM LH8 is a 5,328 cc 90-degree V8 petrol engine engineered for mid-size trucks and SUVs (2008-2012). It combines OHV architecture with exhaust-only VVT to deliver strong low-RPM torque and rugged durability. Designed to meet U.S. Tier 2 Bin 5 standards, it prioritizes towing capacity and off-road performance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 5,328 cc | |
| Fuel type | Petrol (Gasoline) | |
| Configuration | 90° V8, OHV, 2 valves per cylinder | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 99.0 mm × 86.0 mm | |
| Power output | 300 hp (224 kW) | |
| Torque | 320 lb-ft (434 Nm) | |
| Fuel system | Sequential multi-port fuel injection (SFI) | |
| Emissions standard | U.S. Tier 2 Bin 5 | |
| Compression ratio | 9.9:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven camshaft with VVT actuator | |
| Oil type | SAE 5W-30 API SM/SN | |
| Dry weight | 485 lb (220 kg) |
The OHV/VVT design provides exceptional low-end torque ideal for towing and off-roading but requires vigilance for the known exhaust cam VVT actuator weakness. Using the specified SAE 5W-30 oil and adhering to 5,000-mile change intervals is critical to ensure proper actuator lubrication. The cast iron block offers durability but adds weight. Spark plug replacement is straightforward. Vehicles exhibiting reduced power or P0014/P0024 codes should have the VVT actuator inspected per GM bulletin 10-06-01-003.
Oil Specs: Requires SAE 5W-30 meeting API SM/SN specification (GM Owner's Manual). Dexos1 Gen 2 is a suitable modern equivalent.
Emissions: Tier 2 Bin 5 certification applies to all 2008-2012 LH8 engines (EPA 3GAXV05.3LBAK).
Power Ratings: Measured under SAE J1349 standards. Output is consistent across all applications (GM Powertrain Manual PTM-5300-08).
GM Technical Service Bulletins: 10-06-01-003
GM Service Manual SM-5300-01
U.S. Environmental Protection Agency (EPA) Engine Certification Database
SAE International: J1349 Engine Power Certification Standards
The GM LH8 was used across GM's GMT355 platform with longitudinal mounting and no external licensing. This engine was a performance upgrade over the base LLR 3.7L I5, featuring unique engine mounts and accessory brackets for the Hummer H3 versus the Colorado/Canyon. From 2010, the VVT actuator was revised for improved durability, creating a key service part 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 5300-001). The 8th digit of the VIN is '8' for vehicles equipped with the LH8 engine. Pre-2010 engines have an earlier-design VVT actuator (P/N 12607891) prone to failure; post-2010 units have a revised actuator (P/N 12633353). Critical differentiation from the similar LMG 5.3L: The LH8 is based on the 3.7L Atlas I5 block (bore spacing 102.0 mm) while the LMG is based on the LS small-block V8 (bore spacing 101.6 mm).
The LH8's primary reliability risk is exhaust cam VVT actuator failure, with elevated incidence in high-mileage or poorly maintained vehicles. GM internal data indicated a significant number of warranty claims for actuator replacement, while owner reports consistently cite reduced power and check engine lights as common symptoms. Extended oil change intervals and use of incorrect oil viscosity make the updated actuator and strict maintenance critical.
Analysis derived from GM technical bulletins (2008-2012) and NHTSA complaint data (2008-2015). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about GM LH8.
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