The Cadillac LY9 is a 5,967 cc, V8, naturally aspirated petrol engine produced between 2007 and 2011. It features a pushrod OHV 16-valve configuration with Active Fuel Management (AFM) and sequential fuel injection (SFI), delivering 268 kW (365 PS) in standard applications. Designed as a refined, high-torque powerplant, it emphasizes low-RPM drivability and smooth power delivery for luxury performance driving.
Fitted to models such as the Cadillac STS, DTS, and high-trim SRX, the LY9 was engineered to provide seamless power delivery and superior ride comfort. Emissions compliance was achieved through exhaust gas recirculation (EGR), catalytic converters, and oxygen sensor feedback control, enabling it to meet U.S. Tier 2 Bin 5 standards across its production run.
One documented update occurred in 2009, referenced in GM Service Bulletin #10478, which revised the engine control module (ECM) calibration to improve idle stability and reduce cold-start emissions. This change addressed early reports of hesitation and stalling in stop-start traffic and enhanced long-term reliability across the model line.
Production years 2007–2009 meet U.S. Tier 2 Bin 5 standards; 2010–2011 models comply with OBD-II requirements (EPA Certification #GML-EMS-8980).
The Cadillac LY9 is a 5,967 cc V8 naturally aspirated engine engineered for full-size luxury applications (2007–2011). It combines pushrod OHV architecture with sequential fuel injection to deliver smooth, linear power and strong low-end torque. Designed to meet Tier 2 Bin 5 emissions, it prioritizes ride comfort and reliability over high-RPM performance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 5,967 cc | |
| Fuel type | Petrol | |
| Configuration | V8, OHV, 16-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 101.6 mm × 92.0 mm | |
| Power output | 268 kW (365 PS) @ 6,100 rpm | |
| Torque | 515 Nm @ 4,200 rpm | |
| Fuel system | Sequential Fuel Injection (SFI) | |
| Emissions standard | U.S. Tier 2 Bin 5 | |
| Compression ratio | 10.1:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven (double-row, front-mounted) | |
| Oil type | GM Dexos1 Gen 1 (SAE 5W-30) | |
| Dry weight | 215 kg |
The pushrod V8 layout with SFI provides smooth, linear power ideal for relaxed cruising but requires adherence to maintenance schedules to sustain longevity. GM Dexos1 Gen 1 (5W-30) oil is recommended for optimal lifter and camshaft lubrication. Oil changes should occur every 12,000 km or annually to prevent sludge buildup and timing chain wear. The OBD-II system relies on oxygen sensor feedback and EGR function; degraded sensors or clogged EGR passages can trigger driveability issues. Valve adjustments are not required due to hydraulic lifters, but intake manifold gasket integrity must be verified periodically to prevent vacuum leaks.
Oil Specs: Requires GM Dexos1 Gen 1 (5W-30) specification (GM Service Bulletin 10478). Compatible with API SM/SL requirements.
Emissions: U.S. Tier 2 Bin 5 certification applies to all production years (EPA Certification #GML-EMS-8980). No Euro compliance variants were produced.
Power Ratings: Measured under SAE J1349 standards. Output achieved with 87 AKI fuel and optimal ignition timing (GM TIS Doc. A59PERF).
General Motors Technical Information System (TIS): Docs ALY9, A59FUEL, A59TIMING
EPA Certification Database (GML-EMS-8980)
SAE International: J1349 Engine Power Measurement Standard
The Cadillac LY9 was used across Cadillac's STS, DTS, and SRX platforms with longitudinal mounting. This engine received platform-specific adaptations-revised engine mounts in the STS-V and modified transmission tuning in the SRX-and from 2009 the updated STS models adopted revised ECU calibration to improve idle stability, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right-side of the cylinder block, near the exhaust manifold (GM TIS ALY9ID01). The 8th VIN digit indicates engine family ('T' for LY9 series). Pre-2009 models have a composite intake manifold with round throttle body; the 2009+ variant features revised AFM solenoid placement and updated ECU mapping. Critical differentiation from L76: LY9 has higher-flow cylinder heads and different camshaft profile. Service parts require model-year verification—intake manifolds, camshafts, and ECUs are not interchangeable between L76 and LY9 variants (GM TIS ALY9).
The LY9's primary reliability risk is intake manifold gasket failure on high-mileage engines, with elevated incidence in vehicles used for short trips. Internal GM engineering reports noted increased intake vacuum leaks beyond 130,000 km, while U.S. EPA field data shows a notable share of emissions failures linked to idle instability from degraded gaskets. Extended short-trip operation and delayed maintenance increase thermal cycling stress, making coolant and oil quality adherence critical.
Analysis derived from GM technical bulletins (2007-2011) and U.S. EPA emissions failure statistics (2010-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about CADILLAC LY9.
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