🏷️ Basic Information Identification Make: Mercedes-Benz Model: 300 SD Turbo Model Code: W126 (Sedan) Chassis Code: W126.120 Production Years: 1981-1985 👋 Introduction Market Position Segment: Full-size luxury sedan Target Audience: Discerning buyers valuing comfort, durability, and diesel efficiency; also owners seeking comprehensive DIY repair resources. Competitive Analysis Competitors: BMW 7 Series (E23), Audi 5000, Cadillac Eldorado/Seville, Lincoln Continental. Unique Selling Proposition: Renowned Mercedes-Benz build quality, exceptional diesel engine longevity and fuel economy, comfortable ride, robust chassis. Key Features Design Philosophy: Understated elegance, functional luxury, engineering excellence. Powertrain Emphasis: Robust and efficient turbocharged diesel engine offering exceptional torque and long-term reliability. 📋 Manual Details Coverage Areas Engine Overhaul: Complete Transmission Service: Complete Suspension And Steering: Complete Brake System: Complete Electrical System: Complete Body And Chassis: Complete HVAC System: Complete Fuel System And Emissions: Complete Page Count Estimated Pages: Approximately 1000+ Manual Type Type: Factory Service Manual / Repair Manual Language Language: English Format Format: Digital (likely PDF) 📖 Manual Coverage Systems Covered Engine Mechanical: Detailed rebuild procedures for OM617.952 diesel engine, including cylinder head, block, crankshaft, pistons, connecting rods, timing components. Engine Management: Fuel injection system (Bosch inline injection pump), glow plug system, exhaust system. Transmission: 4-speed automatic transmission (722.3) overhaul, operation, adjustments, and troubleshooting. Drivetrain: Rear axle assembly, driveshaft, CV joints, limited-slip differential (if equipped). Suspension: Front independent suspension (double wishbone), rear independent suspension (multi-link), springs, shock absorbers, sway bars, bushings. Steering: Power steering system, steering gearbox, steering linkage, steering column. Brakes: Front disc brakes (ventilated), rear disc brakes, hydraulic system, parking brake, ABS (if equipped - early systems). Electrical System: Wiring diagrams, charging system (alternator), starting system (starter), battery, lighting, instrumentation, interior electronics, power accessories. Climate Control: Air conditioning system diagnosis and repair, heater core, blower motor, climate controls. Body: Body panels, doors, windows, locks, exterior trim, bumpers, sunroof (if equipped). Interior: Seats, upholstery, dashboard, trim panels, safety belts. Procedures Included Routine Maintenance: Oil changes, filter replacements, fluid checks and top-offs, tire rotation, belt inspections. Diagnostic Troubleshooting: Systematic diagnostic procedures for common and uncommon faults across all major vehicle systems. Repair And Rebuild: Detailed step-by-step instructions for component removal, disassembly, inspection, repair, and reassembly. Adjustment And Calibration: Procedures for adjusting idle speed, injection timing, transmission detent pressure, brake adjustments, etc. Torque Specifications: Comprehensive list of torque values for all critical fasteners. Wiring Diagrams: Detailed electrical schematics for the entire vehicle. Technical Depth Depth: Factory-level detail, suitable for professional mechanics and experienced DIY enthusiasts. Covers diagnostics, component-level repair, and complete system overhauls. 📊 Manual Specifications File Format Searchability: Likely text-searchable PDF, allowing for quick retrieval of specific information. Print Quality Quality: High-resolution scans of original factory documentation, ensuring clarity of text and diagrams. Binding Type Binding: N/A (Digital Format) Paper Type Paper: N/A (Digital Format) ⚙️ Engine Specifications Primary Engine Engine Code: OM617.952 Engine Type: Inline-five cylinder, naturally aspirated diesel (though the manual specifically covers the turbocharged variant) Displacement: 3.0 Liters (2998 cc) Bore X Stroke: 90.9 mm x 107.9 mm Compression Ratio: 21.0:1 Performance Horsepower: 123 hp @ 4350 rpm (approx.) Torque: 183 lb-ft @ 2400 rpm (approx.) Fuel System Injection System: Bosch inline mechanical injection pump with turbocharger, intercooler. Fuel Type: Diesel fuel Lubrication Oil Capacity Quarts: 7.4 (with filter) Recommended Oil Viscosity: SAE 15W-40 or 20W-50 (depending on climate and manufacturer recommendation for diesel engines of this era) 🔧 Transmission Standard Transmission Type: 4-speed automatic (722.3) Optional Transmission Type: 5-speed manual (less common, but available in some markets) Features Torque Converter Lockup: Yes Transmission Fluid Type: MB 236.1 (Dexron II equivalent) Transmission Fluid Capacity Quarts: 7.5 (approx.) 📐 Dimensions Exterior Length Inches: 195.1 Width Inches: 70.5 Height Inches: 56.1 Wheelbase Inches: 112.6 Weights Curb Weight Lbs: 3700-3800 (approx.) Gross Vehicle Weight Rating Lbs: 4900 (approx.) Cargo Trunk Volume Cubic Feet: 18.7 (approx.) 🛡️ Safety Features Ratings NHTSA Crash Test Rating: Not available for this era's specific rating system, but generally considered very safe for its time. Active Features ABS: Optional anti-lock braking system (on later models of this generation). Traction Control: Not typically equipped. Passive Features Airbags: Driver's side airbag introduced during the W126 lifecycle, often optional or standard on later models. Seat Belts: 3-point front and rear seat belts. Crumple Zones: Designed with energy-absorbing crumple zones. 💡 Technology Features Infotainment Audio System: Factory AM/FM cassette stereo, often with optional power antenna and upgraded speaker systems. Display: Analog gauges, climate control indicators, basic warning lights. Driver Assistance Cruise Control: Standard on most models, vacuum or electronically controlled. Connectivity Connectivity Options: Limited to analog communication (e.g., antenna for radio). Convenience Power Accessories: Power windows, power door locks, power mirrors, power antenna, power seats (optional). 🔧 Maintenance Service Intervals Oil Change Interval Miles: Every 3,000 - 5,000 miles (depending on driving conditions and oil quality, consult manual for precise recommendations). Fuel Filter Replacement Miles: Every 10,000 - 15,000 miles...