🏷️ Basic Information Identification Make: Mercedes-Benz Model: 420SEL Chassis Code: W126 Model Years Covered: 1986-1991 Generation Generation Code: Second Generation W126 Codes Engine Code Variant: M116 (4.2L V8) 👋 Introduction Market Position Segment: Full-size Luxury Sedan Brand Reputation: Known for engineering excellence, durability, and luxury features. Competitive Analysis Key Competitors: BMW 7 Series, Jaguar XJ, Cadillac DeVille Key Features Vehicle Usp: Spacious interior, refined ride, powerful V8 engine, advanced (for its time) safety and comfort features. Manual Value Proposition Target Audience: Mercedes-Benz owners, independent repair shops, automotive enthusiasts, DIY mechanics. 📋 Manual Details Coverage Areas Primary Coverage: Complete Factory Service and Repair Specific Sections Mentioned: Engine, Brakes, Suspension, Seats, Exterior Trim Page Count Estimated Page Count: Extensive (typical factory manuals exceed 1000 pages) Manual Type Type: Factory Workshop Service Repair Manual Language Language: English Format Digital Format: HTML/Flash menu with PDF content 📖 Manual Coverage Systems Covered Powertrain: Engine mechanical, fuel system, ignition system, cooling system, lubrication system, exhaust system, transmission (automatic) Chassis: Suspension (front and rear), steering system, braking system (hydraulic, ABS), wheels and tires Electrical: Vehicle electrical system, charging system, starting system, lighting system, instrument cluster, comfort modules, electronic control units (ECUs) Body: Body construction, interior trim, exterior trim, seats, doors, windows, HVAC system, body hardware Procedures Included Maintenance: Scheduled maintenance, fluid changes, filter replacements, inspections Repair And Rebuild: Engine overhaul, transmission rebuild, brake component replacement, suspension component replacement, electrical system diagnostics and repair Diagnostics: Troubleshooting guides, fault code interpretation (where applicable for the era), diagnostic procedures for various systems Technical Depth Depth: Comprehensive, covering everything from routine maintenance to complete component rebuilds, suitable for professional technicians and advanced DIYers 📊 Manual Specifications File Format Digital Interface: HTML/Flash menu for navigation Document Format: PDF (for detailed repair procedures and diagrams) Print Quality Printability: High-resolution, printable pages Binding Type Digital Access: Downloadable digital file (no physical book) Paper Type Digital Readability: Optimized for screen viewing and printing Compatibility Operating Systems: Windows (95, 98, ME, XP, Vista, 7), Linux, macOS ⚙️ Engine Specifications Primary Engine Engine Code: M116 Engine Type: SOHC V8 Displacement: 4.2 liters (4196 cc) Performance Horsepower: Approx. 200-220 hp (depending on year and specific tuning) Torque: Approx. 240-250 lb-ft (depending on year and specific tuning) Fuel System Fuel Injection: Bosch K-Jetronic (CIS) or KE-Jetronic (CIS-E) with electronic timing control Engine Management Ignition System: Electronic ignition (e.g., Bremi or Bosch distributors) Lubrication Oil Capacity: Approx. 8.0 liters (with filter) Cooling System Coolant Capacity: Approx. 12.0 liters 🔧 Transmission Standard Transmission Type: 4-speed Automatic (e.g., 4G-TRONIC) Optional Optional Transmission: None offered for 420SEL in this period. Features Transmission Control: Hydraulic control with electronic assistance for smoother shifts. Fluid Specifications Transmission Fluid Type: MB 236.1 or equivalent ATF (e.g., Dexron II/III, check specific manual) 📐 Dimensions Exterior Length: Approx. 5000-5050 mm Width: Approx. 1790 mm Height: Approx. 1400 mm Interior Wheelbase: Approx. 2940 mm (SEL designation indicates long wheelbase) Weights Curb Weight: Approx. 1750-1850 kg 🛡️ Safety Features Ratings Crash Test Era: Pre-modern standardized testing, but known for robust body structure. Active Features ABS: Anti-lock Braking System (ABS) standard on later models/optional earlier Traction Control: ASR (Acceleration Skid Control) may be available on later models, often electronically controlled Passive Features Airbags: Driver's airbag became standard during this generation's run (introduced 1981, widely adopted later). Seatbelts: Pretensioners for front seatbelts Structure: Reinforced passenger cell, crumple zones 💡 Technology Features Infotainment Audio System: Factory-installed Becker or Blaupunkt AM/FM stereo with cassette player. Optional CD changer availability on later models. Climate Control: Automatic climate control (optional on some trims/early models, standard on SEL). Driver Assistance Cruise Control: Standard cruise control system. Memory Seats: Power adjustable front seats with memory function (often included on SEL). Connectivity Antenna System: Power-operated antenna, often integrated into the rear pillar. 🔧 Maintenance Service Intervals Oil Change Interval: Typically 10,000-15,000 km or 12 months (consult manual for exact spec). Major Service Interval: e.g., 50,000-100,000 km for spark plug replacement, transmission service, etc. Fluid Specifications Engine Oil Spec: API SG/SH, ACEA A2/A3, viscosity typically 10W-40 or 15W-40 (check manual for ambient temp suitability) Coolant Type: Glycol-based antifreeze (MB 325.0 or equivalent) Brake Fluid Type: DOT 3 or DOT 4 (ensure compatibility with ABS if equipped) Known Issues Common Wear Items: Ignition components (distributor cap, rotor, wires), fuel distributor and accumulator (K-Jetronic), fuel pumps, vacuum lines, OVP relay (if equipped), climate control servo motors. Body Corrosion: Susceptible to rust in common areas like wheel wells, rocker panels, and battery tray areas, especially in humid climates. Electrical Gremlins: Older wiring harnesses can degrade, leading to intermittent electrical issues. Check fuse box connections. 📚 Vehicle History Brand Heritage Brand Focus: Long history of luxury automotive manufacturing, pioneering safety and engineering. Model Evolution W126 Introduction: W126 generation introduced in 1979 as a successor to the W116 S-Class. Facelift Updates: Significant facelift occurred in 1985,...