🏷️ Basic Information

Make:

Mercedes-Benz

Model:

350SDL

Chassis Code:

W126

Model Years Covered:

1990-1991

Product Name:

Mercedes-Benz 350SDL W126 1990-1991 Factory Workshop Service Repair Manual

Vehicle Segment:

Full-size Luxury Sedan

👋 Introduction

Market Position:

The Mercedes-Benz W126 S-Class, and specifically the 350SDL variant, represented the pinnacle of luxury and engineering in its era. This manual positions itself as the definitive resource for maintaining and repairing these sophisticated vehicles, mirroring the tools used by authorized Mercedes-Benz service centers.

Competitive Analysis:

Compared to generic repair manuals, factory workshop manuals like this offer unparalleled accuracy and detail specific to the vehicle's design and components. It provides OEM-level technical data, which is crucial for the complex systems found in a Mercedes-Benz of this vintage.

Key Features:

Authentic factory documentation, comprehensive system coverage, detailed diagnostic procedures, high-quality illustrations and diagrams, essential for preserving vehicle integrity and performance.

📋 Manual Details

Coverage Areas:

Engine, Brakes, Suspension, Seats, Exterior Trim, Transmission, Electrical Systems, HVAC, Fuel System, Cooling System, Exhaust System, Steering System, Drivetrain, Body Repair, Chassis, Interior Components, Diagnostic Procedures, Routine Maintenance, Troubleshooting, Component Rebuilds, Specifications

Manual Type:

Factory Workshop Service Repair Manual

Language:

English

Format:

HTML/Flash menu with PDF

Compatibility:

Windows 95/98/ME/XP/Vista/Win7, Linux, MAC

Manual Completeness:

Factory-issued, comprehensive workshop manual covering all aspects of vehicle service and repair as used by Mercedes-Benz dealership technicians.

Delivery Method:

Free Download

Shipping Cost:

No Shipping Cost

📖 Manual Coverage

Systems Covered:

Complete coverage of all mechanical and electrical systems, including engine, transmission, drivetrain, suspension, steering, braking, fuel, cooling, exhaust, HVAC, body, interior, and electrical components.

Procedures Included:

Detailed step-by-step procedures for all maintenance, repair, diagnostic, troubleshooting, and overhaul operations. Includes torque specifications, component removal and installation, adjustments, and system testing.

Technical Depth:

Comprehensive. Covers everything from basic fluid changes and filter replacements to complete engine and transmission rebuilds, advanced electrical system diagnostics, and bodywork repairs. Suitable for professional technicians and advanced DIY enthusiasts.

Diagnostic Procedures:

Detailed diagnostic flowcharts, troubleshooting trees, and fault code interpretation (where applicable for electronic modules of the era).

Body And Trim Coverage:

Includes procedures for removal, installation, repair, and alignment of all exterior trim pieces, bumpers, doors, hood, trunk lid, and interior upholstery and dashboard components.

Electrical System Coverage:

Detailed wiring diagrams, component testing, troubleshooting of the lighting system, ignition system, starting system, charging system, instrument cluster, and all electronic control modules.

📊 Manual Specifications

File Format:

Hybrid (HTML/Flash Menu Navigation, PDF Content)

Print Quality:

High-resolution, printable pages. Searchable PDF content for easy information retrieval.

Binding Type:

Digital Download (No Physical Binding)

Paper Type:

N/A (Digital Format)

Searchability:

PDF format allows for text-based searching of specific terms and component names.

⚙️ Engine Specifications

Engine Type:

OM603 Inline 6-Cylinder Turbocharged Diesel

Engine Displacement:

3.5 Liters (3449 cc)

Horsepower Rating:

Approx. 148 hp @ 4000 rpm (US Market)

Torque Rating:

Approx. 247 lb-ft @ 2400 rpm (US Market)

Fuel System Type:

Bosch Inline Fuel Injection Pump with Turbocharging

Bore X Stroke:

94.0 mm x 80.25 mm

Compression Ratio:

22.0:1

Engine Code:

OM603.960

Engine Control Unit:

Electronic engine control unit (ECU) managing fuel injection timing and quantity, glow plug operation, and other engine parameters.

Cooling System Type:

Pressurized liquid cooling system with belt-driven water pump and engine-driven fan with viscous coupling.

Turbocharger Type:

Garrett AiResearch (typically) VGT or Wastegate controlled turbocharger.

🔧 Transmission

Transmission Type:

4-Speed Automatic (4G-Tronic)

Transmission Features:

Hydraulic torque converter, electronic control unit for shift points, locking torque converter clutch for improved efficiency.

Transmission Fluid Type:

Mercedes-Benz Specification 236.1 (e.g., Mobil ATF 220, Valvoline MaxLife ATF)

Transmission Fluid Capacity:

Approx. 8.0 liters (check manual for exact dry fill and refill capacities)

Gear Ratios:

1st: 3.600, 2nd: 2.400, 3rd: 1.470, 4th: 1.000, Reverse: 4.220 (Typical for 4G-Tronic in this model, exact ratios may vary slightly)

📐 Dimensions

Length:

Approx. 197.9 inches (5027 mm)

Width:

Approx. 70.5 inches (1791 mm)

Height:

Approx. 56.1 inches (1425 mm)

Wheelbase:

Approx. 116.7 inches (2964 mm)

Curb Weight:

Approx. 3900-4100 lbs (1770-1860 kg) depending on options

Gross Vehicle Weight Rating:

Approx. 5200 lbs (2360 kg)

Interior Volume:

EPA classification: Large Luxury Sedan

🛡️ Safety Features

Safety Ratings Era:

Built to meet or exceed stringent safety standards of its time, though official standardized ratings like NHTSA's 5-star system were less common and detailed in that era. Known for robust construction.

Active Safety Features:

Anti-lock Braking System (ABS), power-assisted steering.

Passive Safety Features:

Reinforced passenger cell, crumple zones, dual front airbags (driver and passenger), padded interior surfaces, three-point seat belts with pretensioners.

Headlight Type:

Halogen (European-style clear lens often optional or standard depending on market)

Front Brakes:

Vented Disc Brakes

Rear Brakes:

Solid Disc Brakes

💡 Technology Features

Infotainment System:

Becker Grand Prix cassette player with AM/FM radio, optional CD changer interface.

Climate Control System:

Automatic Climate Control (ACC) with integrated heating, ventilation, and air conditioning. Features electronic sensors for temperature regulation and air distribution.

Power Features:

Power windows, power locks, power adjustable front seats with memory, power sunroof, power antenna, cruise control.

Driver Assistance Features:

ABS, cruise control. Limited by era compared to modern vehicles.

Suspension Type:

Front: Independent, double-wishbone; Rear: Independent, multi-link semi-trailing arm. Self-leveling hydropneumatic suspension often featured on rear.

🔧 Maintenance

Oil Change Interval:

Typically every 7,500-10,000 miles (12,000-16,000 km) or 12 months, whichever comes first. Consult manual for specific recommendations.

Air Filter Replacement:

Inspect annually, replace as needed or every 15,000-30,000 miles (24,000-48,000 km).

Fuel Filter Replacement:

Typically every 15,000-30,000 miles (24,000-48,000 km) for diesel fuel filters.

Transmission Service:

Fluid and filter change recommended every 30,000-60,000 miles (48,000-96,000 km).

Engine Oil Type:

API CD or CE rated diesel engine oil, SAE 15W-40 or 10W-30 depending on climate. Refer to manual for precise MB specification.

Engine Oil Capacity:

Approx. 7.5 liters (with filter change)

Coolant Type:

Mercedes-Benz Specification 325.0 (Ethylene Glycol based, blue color) - Typically a 50/50 mix with distilled water.

Brake Fluid Type:

DOT 3 or DOT 4

Common Issues:

PVC system clogging, vacuum line leaks, blower motor resistor failure, fuel injector seal leaks, wiring harness degradation (especially around engine components), climate control system complexity, potential for diesel particulate buildup in exhaust if not maintained properly.

Oil Filter Part Number:

Example: Mann Filter HU 718/1 x (Confirm with VIN or dealer)

Air Filter Part Number:

Example: Mann Filter C 23 421/1 (Confirm with VIN or dealer)

Fuel Filter Part Number:

Example: Mann Filter WK 80/3 (Confirm with VIN or dealer)

📚 Vehicle History

Brand Heritage:

Mercedes-Benz has a long-standing reputation for engineering excellence, luxury, and durability, particularly with its S-Class lineage, which represents the flagship of their sedan offerings.

Model Evolution:

The W126 chassis, produced from 1979 to 1991, was a significant evolution in the S-Class line, introducing advanced safety features and aerodynamic design. The 350SDL was introduced in the latter part of this generation, offering a longer wheelbase and the efficient turbocharged diesel engine.

Production Years W126:

1979-1991

Production Location:

Germany (Sindelfingen Plant)

Model Significance:

The W126 represented a significant leap in safety and comfort for Mercedes-Benz, setting benchmarks for luxury sedans worldwide. The diesel variants, like the 350SDL, offered exceptional fuel economy without compromising the brand's commitment to performance and refinement.

🏆 Awards & Recognition

Recognitions:

The W126 S-Class series was widely acclaimed for its safety, luxury, and engineering throughout its production run, frequently appearing on 'Best Cars' lists and earning critical praise from automotive journalists globally.