🏷️ Basic Information

Make:

Mercedes-Benz

Model:

W126 S-Class

Model Generation:

First Generation (1979-1991)

Chassis Code:

W126

👋 Introduction

Positioning:

The W126 S-Class represented the pinnacle of luxury and engineering in its era, offering a refined driving experience and advanced technology. This manual serves owners and enthusiasts seeking to maintain or restore these prestigious vehicles.

Competitors:

Competed directly with luxury sedans from BMW (E23 7 Series), Jaguar (XJ Series), and American luxury marques like Cadillac.

Unique Selling Points:

Exceptional build quality, robust engineering, advanced safety features for its time (e.g., ABS, airbags on later models), powerful V8 engines, sophisticated suspension, and luxurious interior appointments.

📋 Manual Details

Covered Model Years:

1979-1991 (all variants within the W126 generation)

Engine Variants Covered:

M116 (3.8L V8), M117 (4.2L V8, 5.0L V8, 5.6L V8), OM617 (3.0L Diesel I5), OM603 (3.0L Diesel I6)

Estimated Page Count:

Over 1000 pages (typical for comprehensive service manuals)

Type:

Service and Repair Manual

Language:

English

Format:

Digital Download (PDF)

📖 Manual Coverage

Engine:

Detailed diagnostics, overhaul, lubrication, cooling, fuel injection (Bosch K-Jetronic/KE-Jetronic, Diesel indirect injection), ignition, emission control systems.

Transmission:

Automatic transmissions (e.g., 722.3, 722.4, 722.5): maintenance, repair, adjustments, torque converter servicing, fluid specifications.

Suspension:

Front and rear suspension components, shock absorbers, springs, ball joints, bushings, steering system (including power steering).

Brakes:

Hydraulic system, ABS (Anti-lock Braking System), brake pads, rotors, calipers, lines, master cylinder, parking brake.

Electrical:

Complete wiring diagrams, troubleshooting for lighting, ignition, starting, charging, climate control, power windows/locks/seats, central locking, instrument cluster, diagnostic codes.

Bodywork:

Panel removal/installation, door mechanisms, window regulators, sunroof operation, trim components, collision repair considerations.

Climate Control:

Air conditioning system (R12), heating system, blower motor, HVAC controls, troubleshooting.

Fuel System:

Fuel tank, fuel pump, fuel lines, fuel filters, fuel injection system details for gasoline and diesel variants.

Maintenance:

Scheduled maintenance (oil changes, filter replacements, fluid checks), tune-ups, lubrication points, belt replacements.

Repair:

Engine rebuild procedures, transmission overhaul, brake system repairs, suspension component replacement, electrical system diagnostics and repair, body panel repairs.

Diagnostics:

Troubleshooting flowcharts, identifying symptoms, interpreting fault codes (OBD I era), diagnostic testing procedures for all major systems.

Assembly Disassembly:

Step-by-step instructions with diagrams for component removal and installation for all major vehicle systems.

Cleaning:

Procedures for cleaning specific engine components, fuel injectors, and other parts during repair.

Painting:

While the manual may not detail painting techniques extensively, it will cover the removal and reinstallation of body panels and trim relevant to painting.

Depth:

Comprehensive. Covers everything from basic maintenance to complete engine and transmission overhauls, including detailed electrical schematics and diagnostic procedures.

Diagrams:

Includes detailed diagrams for assembly and disassembly, wiring schematics, and exploded views of various components.

Troubleshooting:

Provides systematic troubleshooting guides for common and complex issues across all vehicle systems.

📊 Manual Specifications

File Type:

PDF

Searchability:

Searchable text content for quick information retrieval.

Printability:

Printable by section or in its entirety.

Binding:

N/A (Digital)

Paper Quality:

N/A (Digital)

Completeness:

Comprehensive Service and Repair Manual covering all aspects of vehicle maintenance and repair.

⚙️ Engine Specifications

Common V8 Engine:

M117 (4.2L/5.0L/5.6L) SOHC V8

Diesel Engine:

OM603 (3.0L) SOHC Inline-6 Turbo Diesel

Typical Horsepower Range:

140 hp (early diesel) to 260 hp (5.6L V8)

Typical Torque Range:

180 lb-ft (early diesel) to 330 lb-ft (5.6L V8)

Gasoline Fuel Injection:

Bosch CIS (Continuous Injection System) and later CIS-Jetronic (KE-Jetronic)

Diesel Fuel Injection:

Bosch inline injection pump (indirect injection)

Oil Type Recommendation:

API SG or higher, SAE 10W-40 or 15W-40 (check specific model year and climate for precise recommendation)

Coolant Type Recommendation:

Mercedes-Benz approved ethylene glycol coolant (e.g., G48/Z) mixed 50/50 with distilled water.

🔧 Transmission

Standard Transmission:

4-speed Automatic (722.3, 722.4)

Optional Transmission:

5-speed Automatic (722.5 with Lock-up Clutch)

Transmission Fluid Type:

MB 236.1 Specification (e.g., Dexron III compatible, but MB spec is preferred)

Transmission Fluid Capacity:

Approximately 7-8 liters (check specific model for exact capacity)

📐 Dimensions

Wheelbase Standard:

2935 mm (115.6 in)

Overall Length Standard:

4965 mm (195.5 in)

Curb Weight Range:

1600 kg - 1900 kg (depending on engine and options)

🛡️ Safety Features

Historical Safety Perception:

Considered exceptionally safe and robust for its era, with strong unibody construction.

ABS:

Available on later models and as an option.

Airbags:

Driver's airbag became standard on later models (post-facelift, 1986 onwards); passenger airbag optional.

Seatbelts:

Front and rear seatbelts, front pre-tensioners on later models.

💡 Technology Features

Audio System:

Original Becker or Blaupunkt radios with optional CD changers on later models. Analog climate control or early digital climate control systems.

Cruise Control:

Standard on most models.

Early Features:

Power windows, power seats (with memory on some models), central locking, automatic climate control (optional/standard depending on trim).

🔧 Maintenance

Oil Change Interval:

Typically 15,000 km (9,300 miles) or 12 months, whichever comes first (depending on oil quality and driving conditions).

Transmission Service Interval:

Change fluid and filter every 60,000 km (37,000 miles) or as specified in the manual.

Brake Fluid Type:

DOT 4 (or DOT 3 if specified for specific models/markets).

Power Steering Fluid:

MB 236.3 Specification (e.g., Pentosin CHF 11 S or equivalent).

Common Problems Electrical:

Failing vacuum lines for central locking and climate control, deteriorating wiring insulation (especially in engine bay), failure of door lock actuators and window regulators.

Common Problems Mechanical:

Head gasket leaks on V8 engines, fuel distributor issues on CIS systems, idle control valve problems, worn suspension bushings.

Common Problems Body:

Rust in common areas like wheel wells, rocker panels, and around windshield/rear window seals. Deterioration of interior materials.

📚 Vehicle History

Mercedes Benz Legacy:

Mercedes-Benz has a long-standing reputation for engineering excellence, luxury, and durability, established throughout the 20th century.

W126 Development:

Successor to the W116 S-Class, featuring a more aerodynamic design, improved safety, and enhanced comfort. Underwent a significant facelift in 1985 (model year 1986) with cosmetic updates and powertrain enhancements.

Production Years:

1979-1991

Manufacturing Locations:

Germany (Sindelfingen)

🏆 Awards & Recognition

Industry Accolades:

Widely recognized for its safety, comfort, and engineering excellence, frequently cited as a benchmark luxury sedan of its time.