🏷️ Basic Information Identification Make: Mercedes-Benz Model: 420SEL Year: 1990 Codes Chassis Code: W126 Generation Generation Code: Second Generation (W126) 👋 Introduction Market Position Segment: Full-size Luxury Sedan Brand Perception: Represents peak automotive engineering and luxury of its era. Competitive Analysis Key Competitors: BMW 7 Series, Jaguar XJ, Lexus LS 400. Key Features Model Highlights: Smooth ride, powerful V8 engine, advanced (for its time) features, exceptional build quality, long-wheelbase for enhanced rear passenger comfort. Manual Value Proposition Target Audience: Professional mechanics, DIY enthusiasts, and owners seeking to understand and maintain their vehicle. Cost Saving Potential: Enables DIY repairs, empowering owners to avoid dealership labor costs and potentially identify overcharging by independent shops. Content Organization: Presented in over 70 separate PDF sections for targeted access to specific repair or maintenance tasks. 📋 Manual Details Coverage Areas Model Variants Covered: All 1990 Mercedes-Benz 420SEL models Page Count Estimated Page Count: Over 1000 pages Manual Type Manual Type: Service and Repair Manual Language Language: English Format Digital Format: PDF (Portable Document Format) Accessibility: Viewable and printable via Adobe Acrobat Reader 📖 Manual Coverage Systems Covered Engine Mechanical: Engine assembly, cylinder head, crankshaft, pistons, connecting rods, camshafts, valve train, lubrication system, cooling system, fuel injection system (Bosch KE-Jetronic/LH-Jetronic variations). Engine Electrical: Ignition system, starting system, charging system, engine control unit (ECU) diagnostics, sensors, actuators. Transmission: Automatic transmission (4-speed 4G-TRONIC), removal, installation, internal components, torque converter, hydraulic system, electronic control. Drivetrain: Driveshaft, rear axle, differential, CV joints, wheel bearings. Suspension And Steering: Front and rear suspension components (independent), shock absorbers, springs, control arms, ball joints, steering gear, power steering system. Brakes: Hydraulic system, brake discs, brake pads, calipers, ABS (Anti-lock Braking System) components and diagnostics, parking brake. Electrical System: Battery, alternator, starter motor, lighting system, power windows, power seats, central locking, wipers, horn, dashboard instruments, fuses, relays. Body And Chassis: Body structure, doors, hood, trunk lid, bumpers, interior trim, glass, body repair procedures. HVAC: Heating, ventilation, and air conditioning system, components, refrigerant handling, diagnostics. Procedures Included Routine Maintenance: Oil changes, filter replacements (oil, air, fuel), spark plug replacement, fluid level checks and top-offs, battery maintenance. Diagnostic Procedures: Troubleshooting guides for common symptoms, diagnostic codes, test procedures for various components. Repair And Overhaul: Detailed step-by-step instructions for component removal, repair, and reassembly (e.g., engine rebuild, transmission overhaul, brake caliper replacement). Electrical Diagnostics And Repair: Wiring diagrams for all electrical circuits, troubleshooting power delivery issues, component testing, repair of electrical faults. Alignment And Adjustment: Wheel alignment specifications, headlight aim adjustment, idle speed adjustments. Technical Depth Depth Of Information: Comprehensive, covering everything from basic maintenance to full engine and transmission rebuilds. Includes detailed technical specifications and diagnostic procedures. 📊 Manual Specifications File Format PDF Quality: High-resolution, text-searchable Printability: Pages can be printed individually as needed Binding Type Binding Type: N/A (Digital Format) Paper Type Paper Type: N/A (Digital Format) ⚙️ Engine Specifications Primary Engine Engine Type: V8 SOHC (Single Overhead Camshaft) Displacement: 4.2 Liters (4196 cc) Bore X Stroke: 92.0 mm x 78.9 mm Performance Horsepower Net: 228 hp @ 5,000 rpm (approx.) Torque Net: 260 lb-ft @ 3,200 rpm (approx.) Fuel System Fuel Delivery: Bosch Fuel Injection (likely KE-Jetronic or LH-Jetronic) Fuel Type: Premium Unleaded Gasoline Engine Management Engine Control Unit: Electronic Engine Control (EEC) 🔧 Transmission Standard Transmission Type: 4-Speed Automatic (4G-TRONIC) Features Transmission Control: Electronic Control Module (ECM) for shift points and diagnostics. 📐 Dimensions Exterior Wheelbase: 3075 mm (121.1 inches) Length: 5030 mm (198.0 inches) Width: 1790 mm (70.5 inches) Height: 1430 mm (56.3 inches) Weights Curb Weight: 1750 kg (3858 lbs) (approx.) Gross Vehicle Weight Rating: 2350 kg (5180 lbs) (approx.) 🛡️ Safety Features Ratings NHTSA Crash Test Rating: Not specifically rated by NHTSA in modern standardized format for this era, but built to rigorous Mercedes-Benz safety standards of the time. Active Features Active Safety Systems: Anti-lock Braking System (ABS), excellent chassis dynamics, powerful brakes. Passive Features Passive Safety Features: Reinforced body structure, crumple zones, driver and passenger airbags (standard on later W126 models, check VIN for specifics), seatbelt pretensioners, energy-absorbing steering column. 💡 Technology Features Infotainment Audio System: Factory premium sound system, often with cassette player and AM/FM radio. Many owners upgrade to modern head units. Driver Assistance ABS: Standard Anti-lock Braking System (ABS) for enhanced braking control. Comfort Features Power Features: Power windows, power seats (often with memory), power mirrors, power sunroof, central locking. Climate Control Automatic Climate Control: Optional or standard automatic climate control for maintaining cabin temperature. 🔧 Maintenance Service Intervals Oil Change Interval: Typically every 7,500-10,000 miles or 12 months, depending on driving conditions and oil used. Consult manual for specific recommendations. Transmission Fluid Change: Recommended every 30,000-60,000 miles. Check manual for exact interval and fluid type. Fluid Specifications Engine Oil Type: SAE 10W-40 or 15W-50 (API SG or higher), or as specified by Mercedes-Benz. Check owner's manual...