🏷️ Basic Information Identification Make: Mercedes-Benz Model: 300 SEL Model Code: W126 (Long Wheelbase) Production Years Covered: 1988, 1989, 1990, 1991 Codes Engine Codes: M103.980 Chassis Codes: W126.025 👋 Introduction Market Position Segment: Luxury Sedan (Full-Size) Target Audience: Owners seeking to maintain or repair their W126 chassis Mercedes-Benz 300 SEL, including independent repair shops and knowledgeable DIY enthusiasts. Competitive Analysis Competitors Era: BMW 7 Series (E32), Audi V8 Quattro, Cadillac DeVille, Lincoln Town Car. Key Features Vehicle Highlights: The 300 SEL (W126) represents the pinnacle of Mercedes-Benz engineering for its era, offering unparalleled comfort, build quality, and a refined driving experience. Known for its robust construction, sophisticated suspension systems (including optional self-leveling and 4MATIC), and a powerful yet smooth inline-six engine. Manual Value Proposition Dealer Equivalence: Identical to the manuals used by authorized Mercedes-Benz dealerships. 📋 Manual Details Coverage Areas Coverage Type: Comprehensive Factory Service and Repair Specific Models And Years: Mercedes 300 SEL (1988-1991) Page Count Estimated Pages: Extensive (Specific count not provided, but implied to be highly comprehensive) Manual Type Type: Service and Repair Manual Language Language: English Format Format: Digital Download (PDF) 📖 Manual Coverage Systems Covered Engine: Engine oil and filter change, valve clearance adjustment/checking, idle speed checking/adjustment, injection timing, fuel filter replacement, air filter replacement, V-belt/Poly V-belt inspection/tensioning, intake/exhaust manifold seating, oxygen sensor replacement, spark plug inspection/replacement, coolant level/antifreeze protection, cooling/heating system, coolant replacement, engine mount bolts, engine stop adjustment. Drivetrain: Manual transmission oil change/level check, automatic transmission fluid and filter change/level check, transfer case fluid change/level check, clutch disk wear inspection, clutch system fluid check/correction, clutch system inspection, throttle linkage lubrication/inspection, steering play check, steering bolts re-tightening, front axle oil level check, rear axle oil change/level check, rear axle mount adjustment. Suspension And Steering: Suspension and body structure inspection, level control (ADS, 4MATIC) fluid level, self-leveling suspension inspection, front axle ball joint inspection, ball joint inspection (special tool), drive shaft flexible coupling inspection. Brakes: Brake fluid level check, brake lines inspection, brake pads and disc thickness inspection, brake disks inspection/cleaning, parking brake cable inspection, parking brake adjustment, brake fluid replacement, brake test/parking brake check. Electrical: Warning and indicator lamp checks, battery fluid level check. Body And Chassis: Component condition inspection, lines and hoses inspection, water leakage and corrosion inspection, wheel inspection/rotation, tire inspection, tire pressure correction, wheel bolt tightening, exhaust flange re-tightening, exhaust system connections re-tightening, water drain cleaning, engine compartment lower panel removal/installation, door hinge lubrication, door lock lubrication, hydraulic top fluid level check/correction, sunroof rail cleaning/greasing, soft top locking tab check, windshield washer fluid level check/correction, antenna mast cleaning, headlamp and exterior lamp inspection, windshield wiper and washer inspection, windshield wiper blade replacement, hood lubrication, lower noise encapsulation panel removal/installation, body paint damage inspection. Climate Control: Heating and ventilation dust filter replacement, active charcoal filter replacement, recirculating air filter replacement, AC refrigerant charge check/correction. Diagnostics: Troubleshooting procedures and diagnostic flowcharts for various systems, including engine, electrical, and fuel systems. Procedures Included Maintenance: Routine fluid changes (oil, transmission, differential, brake, washer), filter replacements (oil, air, fuel, cabin), belt inspections and adjustments, spark plug replacement, coolant checks, battery checks. Repair: Component replacement (e.g., oxygen sensor, fuel filter, brake components, suspension components), system adjustments (e.g., idle speed, injection timing, parking brake), leak repairs (e.g., water, fluid), electrical component testing (warning lamps). Inspection: Comprehensive inspection of engine components, lines, hoses, suspension, body structure, water leaks, corrosion, tires, brakes, steering, fuel system, electrical system, safety belts, backrest locks. Lubrication: Throttle linkage, door hinges, door locks, sunroof rails, hood. Technical Depth Depth: Factory-level, detailed diagnostic procedures, repair instructions, and component specifications. Suitable for professional technicians and advanced DIY enthusiasts. 📊 Manual Specifications File Format Format: PDF Searchability: Fully searchable text Print Quality Printability: All pages printable Binding Type Binding: N/A (Digital Download) Paper Type Paper Type: N/A (Digital Download) File Integrity File Quality: Real files, not scans ⚙️ Engine Specifications Primary Engine Engine Type: Inline-6 Cylinder, DOHC Displacement: 3.0 Liters (2960 cc) Bore X Stroke: 88.5 mm x 80.25 mm Compression Ratio: 9.2:1 Performance Horsepower: 189 hp @ 5700 rpm (approx.) Torque: 207 lb-ft @ 4400 rpm (approx.) Fuel System Fuel Delivery: Bosch KE-Jetronic Fuel Injection (Mechanical/Electronic Hybrid) Fuel Requirements Octane Rating: Premium Unleaded (91 RON or higher) Cooling System Coolant Capacity: Approx. 9.0 Liters (with heater core) Lubrication System Oil Capacity: Approx. 7.5 Liters (with filter) Recommended Oil Viscosity: SAE 15W-40 or 10W-40 (depending on climate) 🔧 Transmission Standard Type: 4-Speed Automatic (722.3 / 722.4 series) Optional Type: None for 300 SEL in these years Features Transmission Fluid Type: MB 236.1 / MB 236.2 / Dexron II (refer to manual for exact specification) Transmission Fluid Capacity: Approx. 7.0 Liters (for torque converter refill) 📐 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...