🏷️ Basic Information Identification Make: Mercedes-Benz Model: W126 SEL Year: 1981 Generation Generation Code: First Generation W126 👋 Introduction Market Position Positioning: The W126 was Mercedes-Benz's flagship S-Class sedan, representing the pinnacle of luxury, engineering, and safety for its era. This manual serves owners and independent technicians seeking to maintain and repair these sophisticated vehicles. Competitive Analysis Comparison: Competed with high-end sedans from BMW (e.g., 7 Series), Jaguar (XJ), and Cadillac (Fleetwood). Key Features Distinctive Elements: Known for its aerodynamic design, advanced safety features for the time (e.g., ABS on later models, early SRS concepts), robust build quality, and luxurious interior. The SEL denotes the long-wheelbase version, offering increased rear passenger space. 📋 Manual Details Coverage Areas Manual Coverage: Comprehensive A-Z repair and service for all W126 SEL models Page Count Estimated Page Count: Likely 1000+ pages, typical for full dealer service manuals of this era. Manual Type Manual Type: Factory Service and Repair Manual Language Language: English Format Format: PDF 📖 Manual Coverage Systems Covered Powertrain: Engine (M110, M117), Fuel System, Cooling System, Lubrication System, Ignition System, Starting System, Charging System, Emission Control System, Automatic Transmission (e.g., 4-speed 722.3) Chassis: Front and Rear Suspension, Drive Shaft, Differential, Axles, Brakes (Hydraulic, Parking), Steering System (including Power Steering) Electrical: Complete Wiring Schematics, Lighting, Instrumentation, Wipers/Washers, Horn, Power Accessories (windows, locks, seats), Meter/Audio/Visual Systems, Air Conditioning, Cruise Control, Supplemental Restraint System (SRS - early forms), Engine Immobilizer (if applicable) Body: Body Shell, Doors, Hood, Exterior Trim, Interior Trim, Glass/Mirrors, Seats, Instrument Panel Procedures Included Maintenance Procedures: Scheduled maintenance, fluid checks and changes, filter replacements, belt inspections and adjustments Diagnostic Procedures: Troubleshooting guides, fault code interpretation (if applicable), component testing Repair Procedures: Step-by-step instructions for engine rebuilds, transmission overhauls, suspension component replacement, brake system repairs, electrical system diagnosis and repair, body panel repair and replacement Technical Data And Specs: Torque specifications, clearances, timing settings, fluid capacities, electrical values, diagnostic parameters Technical Depth Depth: Factory level, enabling complete diagnosis, maintenance, and repair from basic servicing to major component overhauls. 📊 Manual Specifications File Format File Format: Adobe PDF Print Quality Printability: High-resolution, all pages printable. Ability to enlarge images for detailed viewing. Binding Type Binding: Digital (PDF), no physical binding. Paper Type Paper Type: N/A (Digital Format) ⚙️ Engine Specifications Primary Engine Engine Code And Type: Likely M110 (2.8L Inline-6) or M117 (3.8L or 5.0L V8), depending on specific SEL variant for 1981. Performance Horsepower And Torque: Varies by engine. For example, the 3.8L M116 V8 (often found in US SEL models) typically produced around 155-160 hp. The 5.0L M117 V8 would offer more power. (Specific figures in manual). Fuel System Fuel Delivery: Bosch K-Jetronic (CIS - Continuous Injection System) or potentially early electronic fuel injection (EFI) depending on the specific engine and market. 🔧 Transmission Standard Standard Transmission: Likely a 4-speed automatic transmission (e.g., 722.3). Optional Optional Transmission: Manual transmission options were rare on SEL models, especially in the US market. Features Transmission Features: Torque converter lock-up, hydraulic control. 📐 Dimensions Exterior Wheelbase: W126 SEL (Long Wheelbase) has a significantly longer wheelbase than the standard W126, typically around 3086 mm (121.5 inches). Length: Approx. 5170 mm (203.5 inches) for the SEL. Weights Curb Weight: Varies by engine and equipment, but typically around 1700-1900 kg (3750-4200 lbs). 🛡️ Safety Features Ratings Historical Safety Focus: Mercedes-Benz placed a strong emphasis on safety, incorporating crumple zones, safety cage construction, and advanced restraint systems for the era. Active Features ABS: Anti-lock Braking System (ABS) became available on W126 models, though may not have been standard on all 1981 SEL variants. Passive Features Airbags: Driver's airbag was introduced later in the W126's lifecycle, so likely not standard on 1981 SEL. Supplemental Restraint System (SRS) was a developing technology. 💡 Technology Features Infotainment Audio System: Factory-installed Becker radio/cassette players were common, often with options for power antenna and multiple speakers. Driver Assistance Cruise Control: Cruise control was available and a significant technological feature for its time. Connectivity Early Electronics: The manual will cover the extensive electrical system and early integrated electronics for climate control, power accessories, and instrumentation. 🔧 Maintenance Service Intervals Oil Change Interval: Typically every 5,000 to 7,500 miles (8,000 to 12,000 km) or annually, depending on driving conditions and specific engine oil used. (Manual will specify). Major Service Intervals: Includes spark plug replacement, fuel filter replacement, and transmission fluid service, often at intervals of 30,000 miles (48,000 km) or more. (Manual provides detailed schedule). Fluid Specifications Engine Oil Type: API SF or SG classification, viscosity SAE 10W-40 or 10W-30 recommended for many climates, but specific grades are critical. (Manual is the definitive source). Transmission Fluid Type: Typically MB-Approval 236.3 Dexron II (or equivalent) for the automatic transmission. (Crucial to use correct fluid). Coolant Type: Ethylene glycol-based antifreeze. Manual specifies mixture ratio and MB approval number. Known...