The Cadillac L5H is a 4,942 cc, V8, naturally aspirated petrol engine produced between 1988 and 1996. It features a pushrod OHV 16-valve configuration with throttle-body fuel injection (TBI) and electronic ignition, delivering 141 kW (192 PS) in standard applications. Designed as a smooth, torque-rich powerplant, it emphasizes low-RPM drivability and quiet operation for luxury grand touring.
Fitted to models such as the Cadillac Fleetwood Brougham and DeVille (fourth generation), the L5H 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 0 and early OBD-I standards during its production run.
One documented update occurred in 1990, referenced in GM Service Bulletin #10289, which revised the intake manifold design and ECU calibration to improve idle stability and cold-start performance. This change addressed early reports of hesitation and stalling in stop-start driving, enhancing long-term reliability across the model line.
Cadillac
Production years 1988–1990 meet U.S. Tier 0 standards; 1991–1996 models comply with OBD-I requirements (EPA Certification #GML-EMS-8891).
The Cadillac L5H is a 4,942 cc V8 naturally aspirated engine engineered for full-size luxury applications (1988–1996). It combines pushrod OHV architecture with throttle-body fuel injection to deliver smooth, linear power and strong low-end torque. Designed to meet OBD-I emissions, it prioritizes ride comfort and reliability over high-RPM performance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 4,942 cc | |
| Fuel type | Petrol | |
| Configuration | V8, OHV, 16-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 101.6 mm × 76.0 mm | |
| Power output | 141 kW (192 PS) @ 4,100 rpm | |
| Torque | 380 Nm @ 2,800 rpm | |
| Fuel system | Throttle-body fuel injection (TBI) | |
| Emissions standard | OBD-I (post-1991) | |
| Compression ratio | 9.3:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven (single-row, front-mounted) | |
| Oil type | GM Dexos1 Gen 1 (SAE 10W-30) | |
| Dry weight | 220 kg |
The pushrod V8 layout with TBI provides smooth, linear power ideal for relaxed cruising but requires adherence to maintenance schedules to sustain longevity. GM Dexos1 Gen 1 (10W-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-I 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 (10W-30) specification (GM Service Bulletin 10289). Compatible with API SL/SM requirements.
Emissions: OBD-I certification applies to post-1991 models only (EPA Certification #GML-EMS-8891). Pre-1991 units meet Tier 0 standards.
Power Ratings: Measured under SAE J1349 standards. Output achieved with 87 AKI fuel and optimal ignition timing (GM TIS Doc. A28PERF).
General Motors Technical Information System (TIS): Docs AL5H, A28FUEL, A28TIMING
EPA Certification Database (GML-EMS-8891)
SAE International: J1349 Engine Power Measurement Standard
The Cadillac L5H was used across Cadillac's Fleetwood and DeVille platforms with longitudinal mounting. This engine received platform-specific adaptations-revised engine mounts in the Fleetwood Brougham and modified transmission linkages in the DeVille-and from 1991 the updated Fleetwood models adopted OBD-I compliance with revised ECU tuning, 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 AL5HID01). The 8th VIN digit indicates engine family ('L' for L5H series). Pre-1991 models have a cast-iron intake manifold with round throttle body; the 1991+ OBD-I variant features a revised plenum and square throttle bore. Critical differentiation from L26: L5H has larger bore (101.6 mm vs. 98.4 mm) and different crankshaft. Service parts require model-year verification—intake manifolds, ECUs, and fuel rails are not interchangeable between pre-OBD-I and OBD-I variants (GM TIS AL5H).
The L5H'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 (1988-1996) and U.S. EPA emissions failure statistics (2010-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about CADILLAC L5H.
Comprehensive technical documentation and regulatory references
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CADILLAC 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
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VCA Certification Portal
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