🏷️ Basic Information Identification Make: Mercedes-Benz Model: 350 SD Turbo Year: 1991 Codes Chassis Code: W140 (S-Class) Engine Code: OM603.970 👋 Introduction Market Position Market Position: The Mercedes-Benz W140 chassis represented the pinnacle of luxury automotive engineering in its time, competing with top-tier offerings from BMW (E32 7 Series) and Lexus (LS 400). The 350 SD Turbo was positioned as a refined, powerful, and fuel-efficient diesel variant within the S-Class lineup. Competitive Analysis Competitive Analysis: At its introduction, the W140 S-Class, including the 350 SD Turbo, was praised for its build quality, advanced technology, and quiet cabin. It faced stiff competition from other German luxury marques and the emerging Japanese luxury segment. This manual provides the specific knowledge required to maintain and repair a vehicle that was a benchmark in its class. Key Features Key Features: The 350 SD Turbo's key features include its robust turbocharged diesel engine, luxurious interior appointments, advanced safety systems for its era, and the sophisticated engineering characteristic of Mercedes-Benz vehicles of this period. 📋 Manual Details Coverage Areas Coverage Summary: Comprehensive service and repair for all mechanical and electrical systems of the 1991 Mercedes-Benz 350 SD Turbo (W140). Page Count Page Count Estimate: Approximately 1500-2000 pages (typical for a full workshop manual of this era) Manual Type Manual Type: Workshop Service Repair Manual Language Language: English Format Format: Digital (likely PDF), printable 📖 Manual Coverage Systems Covered Engine: Complete engine overhaul, diagnostics, fuel system, cooling system, lubrication, intake and exhaust systems, turbocharger system. Transmission: 4-speed automatic transmission (722.3xx series) overhaul, diagnostics, fluid services, control systems. Drivetrain: Rear-wheel drive, driveshaft, differential, axle shafts. Suspension: Front and rear suspension components, shock absorbers, springs, bushings, hydraulic leveling system (if applicable). Brakes: Hydraulic brake system, ABS (Anti-lock Braking System), brake fluid, calipers, rotors, pads, lines, parking brake. Steering: Power steering system, steering column, steering gear. Electrical: Complete electrical schematics, battery, charging system, starter, ignition system, lighting, instrument cluster, power accessories, ECU diagnostics. Climate Control: Automatic climate control system (Klimatronik), A/C system, heating, ventilation, refrigerant. Body And Chassis: Body panels, doors, windows, locks, exterior trim, interior trim, chassis components, corrosion protection. Diagnostics: On-board diagnostics (OBD) information, troubleshooting guides, fault code interpretation, wiring diagrams for diagnosis. Procedures Included Scheduled Maintenance: Detailed procedures for routine maintenance, oil changes, filter replacements, fluid checks and top-offs. Component Repair: Step-by-step instructions for component removal, disassembly, repair, reassembly, and installation. Troubleshooting: Systematic troubleshooting charts and symptom-based diagnostics for identifying and resolving issues. Rebuilds: Complete rebuild procedures for major components such as the engine and transmission. Electrical Diagnosis: Detailed diagnostic procedures for electrical circuits and components, including troubleshooting wiring faults. Technical Depth Depth: Expert level: Suitable for professional technicians and advanced DIY mechanics. Covers detailed internal component specifications and repair. 📊 Manual Specifications File Format File Format: PDF Print Quality Print Quality: High-resolution scans, ensuring clarity of diagrams and text for printing. Binding Type Binding Type: N/A (Digital format) Paper Type Paper Type: N/A (Digital format) Searchability Searchability: Searchable text within the PDF document for quick access to information. ⚙️ Engine Specifications Primary Engine Engine Type: Inline 6-cylinder Diesel with Turbocharger Engine Displacement: 3.5 Liters (3449 cc) Engine Code: OM603.970 Bore X Stroke: 94.0 mm x 92.4 mm Compression Ratio: 20.2:1 Valvetrain: SOHC (Single Overhead Camshaft), 12 valves (2 per cylinder) Performance Horsepower: 136 hp (101 kW) at 4000 rpm Torque: 243 lb-ft (329 Nm) at 2000 rpm Fuel System Fuel Injection: Bosch VE (Variable Emission) Mechanical Injection Pump with Diesel Injectors Fuel Type: Diesel Fuel Cooling System Cooling Type: Liquid-Cooled Coolant Capacity: Approximately 10.5 Liters (2.77 US Gallons) Lubrication Oil Capacity: Approximately 7.5 Liters (7.9 US Quarts) Recommended Oil Type: API CD or CE rated diesel engine oil (e.g., Mobil Delvac 1300 Super 15W-40, Shell Rotella T 15W-40). Turbocharger Turbocharger Model: Garrett (specific model number may vary, typically GT32 or similar for this application) Boost Pressure: Approximately 0.9-1.0 bar (13-14.5 psi) nominal 🔧 Transmission Standard Transmission Type: 4-Speed Automatic Transmission Model: 722.370 (part of the robust 722.3xx series) Features Transmission Features: Lock-up torque converter, electronically controlled clutch pressure, winter/economy mode selection. Fluid Specifications Transmission Fluid Type: MB 236.1 (e.g., Mercedes-Benz ATF Dexron II or equivalent) Fluid Capacity Transmission Fluid Capacity: Approximately 8.0 Liters (8.5 US Quarts) for a dry fill, less for a fluid change. 📐 Dimensions Exterior Length: Approx. 5113 mm (201.3 in) Width: Approx. 1886 mm (74.3 in) Height: Approx. 1480 mm (58.3 in) Weights Curb Weight: Approx. 1960 kg (4321 lbs) Gross Vehicle Weight Rating: Approx. 2500 kg (5511 lbs) 🛡️ Safety Features Ratings Safety Ratings Era: As an early 1990s luxury vehicle, specific NHTSA/Euro NCAP ratings as we know them today were not standardized. However, it was designed to meet rigorous safety standards of the era. Active Features Active Safety Features: Anti-lock Braking System (ABS), Traction Control System (ASR - Automatic Slip...