🏷️ Basic Information Identification Make: Mercedes-Benz Model: 420 SEL Model Generation: W126 (Second Generation) Model Code: W126.034 Codes Engine Code Primary: M116 (4.2L V8) Engine Code Variations: E42 (M116 E42) 👋 Introduction Market Position Vehicle Segment: Full-size Luxury Sedan Target Audience Manual: Owners seeking to maintain, repair, or restore their Mercedes-Benz 420 SEL, DIY enthusiasts, independent repair shops. Competitive Analysis Contemporary Competitors: BMW 7 Series (E23/E32), Audi V8 quattro, Jaguar XJ6, Cadillac Fleetwood Brougham, Lincoln Town Car. Key Features Vehicle Features Highlight: Long wheelbase (SEL designation), powerful V8 engine, sophisticated suspension, luxurious interior, advanced safety features for its era. Manual Value Proposition: Provides professional-level repair and maintenance information, empowering owners with the confidence and knowledge to service their vehicle independently. 📋 Manual Details Coverage Areas Applicable Years: 1986, 1987, 1988, 1989, 1990, 1991 Specific Models: Mercedes-Benz 420 SEL Page Count Estimated Page Count: Comprehensive (Specific number not provided, but implied to be extensive) Manual Type Manual Type: Service and Repair Manual Language Language: English Format File Format: PDF / WINRAR (Digital Download) 📖 Manual Coverage Systems Covered Engine: Engine mechanical, fuel injection, ignition, lubrication, cooling, exhaust Transmission: Manual Transmission (if applicable to specific VINs), Automatic Transmission (4-speed 4G-TRONIC) Drivetrain: Rear Wheel Drive (RWD), Front axle, Rear axle, Driveshaft Suspension: Front and rear suspension, Level control systems (ADS, 4MATIC), ball joints Brakes: Hydraulic braking system, parking brake, brake fluid, pads, discs, lines Steering: Power steering system, steering column, steering play Electrical: Battery, charging system, starter, lighting, ignition, wiring schematics Body And Chassis: Body structure, corrosion, water leaks, door hinges, locks, hood, sunroof, soft top, exterior lamps Climate Control: Heating, ventilation, air conditioning (HVAC), dust filters, refrigerant charge Procedures Included Maintenance: Regular service, oil and filter changes, fluid checks and replacements, belt inspection, spark plug replacement Diagnostics: Troubleshooting, component condition inspection, system checks (fuel, ignition, cooling) Repair Rebuild: Engine rebuild procedures, transmission overhauls, brake caliper replacement, suspension component replacement Adjustments: Valve clearance adjustment, idle speed adjustment, injection timing adjustment, parking brake adjustment Inspections: Component condition, lines and hoses, suspension, body structure, water leakage, corrosion, brake system, steering play Technical Depth Depth Of Coverage: Comprehensive: Covers basic maintenance to advanced diagnostics and full rebuild procedures, mirroring professional technician information. Detail Level: Step-by-step instructions, detailed diagrams, illustrations, and wiring schematics. 📊 Manual Specifications File Format Digital Format: PDF, WINRAR (ensures compatibility and ease of use) Compatibility: Win95/98/ME/XP/vista/7/8/Linux/MAC, IOS/Android devices Print Quality Printability: Printable pages (implied by digital format for user access) Binding Type Digital Binding: N/A (Digital Download) Paper Type Digital Paper Type: N/A (Digital Download) ⚙️ Engine Specifications Primary Engine Engine Type: Naturally Aspirated V8 Displacement: 4.2 Liters (4196 cc) Bore X Stroke: 92.0 mm x 78.9 mm (approximate) Compression Ratio: 9.2:1 or 10.1:1 (depending on specific market/emission standards) Performance Horsepower Peak: Approx. 180-228 hp (DIN/SAE, depending on model year and market) Torque Peak: Approx. 310-320 Nm (229-236 lb-ft) (depending on model year and market) Fuel System Fuel Delivery: Bosch KE-Jetronic (CIS-E) or similar mechanical/electronic fuel injection system Fuel Type: Premium Unleaded Gasoline (91 Octane or higher) 🔧 Transmission Standard Transmission Type: 4-speed Automatic Transmission (4G-TRONIC) Optional Manual Transmission Availability: Rarely, if ever, offered for the 420 SEL model in most markets. Primarily automatic. Features Automatic Transmission Features: Lock-up torque converter, multiple driving modes (e.g., S/E - Sport/Economy) 📐 Dimensions Exterior Wheelbase: 2936 mm (115.6 inches) Length: 5075 mm (199.8 inches) Width: 1798 mm (70.8 inches) Height: 1440 mm (56.7 inches) Weights Curb Weight: Approx. 1700-1800 kg (3748-3968 lbs) 🛡️ Safety Features Ratings Crash Test Data: Limited official crash test data from this era readily available. Known for robust German engineering and build quality. Active Features Driver Assistance Era: ABS (Anti-lock Braking System), ASD (Automatic Slip Differential) on some models, ADS (Adaptive Damping System) on some models, 4MATIC all-wheel drive available on some variants. Passive Features Passive Safety: Reinforced chassis, crumple zones, safety steering column, padded interior, seat belts. 💡 Technology Features Infotainment Audio System: Factory AM/FM stereo cassette player, optional premium sound systems. Climate Control Tech: Automatic climate control with manual overrides, often featuring recirculating air function and cabin air filters. Driver Assistance Advanced Features Era: While not considered 'driver assistance' by modern standards, features like ABS, optional ASD/ADS, and the robust chassis design were at the forefront for their time. Connectivity Connectivity Features: Very limited by modern standards. Primarily focused on vehicle mechanics and comfort. No Bluetooth or integrated smartphone connectivity. 🔧 Maintenance Service Intervals Oil Change Interval: Typically every 7,500 - 10,000 miles or 12 months, using high-quality synthetic oil. Major Service Intervals: Refer to manual for specific mileage/time-based major service recommendations (e.g., coolant flush, transmission service, spark plug replacement). Fluid Specifications Engine Oil Spec: API SG or higher, SAE 10W-40 or 15W-40 (check owner's manual for specific temperature ranges and approvals). Automatic Transmission Fluid Spec: MB-Approval 236.1 or 236.6...