🏷️ Basic Information

Make:

Mercedes-Benz

Model:

W126 SEC

Year:

1983

Body Style:

Coupe

Generation Code:

C126

👋 Introduction

Positioning:

A premium, luxury coupe representing the pinnacle of Mercedes-Benz engineering and design in the early 1980s. Known for its comfort, performance, and build quality.

Competitors:

BMW 6 Series, Jaguar XJ-S, Porsche 928, Aston Martin V8 Vantage.

Features:

Elegant styling, spacious interior, powerful V8 engines, advanced safety features for its era, refined driving dynamics, extensive use of high-quality materials.

Value:

Provides the exact, detailed factory information used by authorized Mercedes-Benz technicians, enabling owners to perform complex repairs and maintenance accurately, saving time and money compared to dealership service.

📋 Manual Details

Primary Coverage:

All W126 SEC models and all repairs A-Z

Specific Coverage:

Maintenance, Engine, Control System, Mechanical, Fuel Service Specifications, Emission Control, Intake Exhaust Cooling, Lube, Ignition Starting Charging, Auto Transmission, Clutch, Manual Transmission (if applicable to specific W126 SEC models), Transfer Propeller Shaft, Drive Shaft, Differential, Axle Suspension, Tire & Wheel, Brake Control, Brake, Parking Brake, Steering Column, Power Steering, Air Condition, Suppl Restraint System, Seat Belt, Engine Immobilizer (if equipped), Cruise Control, Wiper & Washer, Door Lock, Meter Audio/Visual, Horn, Windshield/Glass Mirror, Instrument Panel, Seat, Engine Hood/Door, Exterior & Interior, Electrical, Multiplex/CAN Communication.

Estimated Page Count:

Extensive (specific count not provided, but described as 'complete step-by-step instructions, diagrams, illustrations, wiring schematics, and specifications'). Estimated to be well over 1000 pages for comprehensive factory coverage.

Type:

Factory Service and Repair Manual

Language:

English

Format:

Digital (PDF)

📖 Manual Coverage

Powertrain:

Engine, Fuel System, Ignition System, Cooling System, Lubrication System, Exhaust System, Automatic Transmission, Clutch (if applicable to specific models).

Chassis:

Suspension (front and rear), Steering System (including power steering), Brakes (hydraulic, ABS if equipped), Wheels and Tires, Drive Axles, Differential.

Electrical:

Ignition, Starting, Charging systems, Lighting, Instrumentation, Wiper/Washer, Horn, Power accessories (windows, locks, seats), HVAC control, Audio/Visual systems, Cruise Control, Supplemental Restraint System (SRS - if equipped), Engine Immobilizer (if equipped), Multiplex/CAN Communication (for advanced systems).

Body And Interior:

Body panels, Doors, Hood, Trunk, Glass, Mirrors, Seats, Interior trim, Exterior trim, Locks, Latches.

Maintenance:

Scheduled maintenance, fluid changes, filter replacements, lubrication, inspections.

Diagnostics:

Troubleshooting guides, symptom-based diagnosis, electrical system diagnosis, engine performance diagnosis.

Repair:

Detailed step-by-step repair procedures for all major and minor components, including engine rebuilds, transmission overhaul, brake system repair, suspension component replacement, electrical system diagnosis and repair.

Specifications:

Torque specifications, clearances, fluid capacities and types, electrical values, diagnostic trouble codes (DTCs) and their meanings.

Depth:

Comprehensive factory-level detail, covering everything from routine maintenance to complete engine and transmission overhauls, including electrical system schematics and diagnostic procedures.

📊 Manual Specifications

Format:

PDF (Portable Document Format)

Compatibility:

Windows (Vista 32/64, XP, ME, 98, NT, 2000) and Mac OS

Printability:

Yes, all pages are printable. Allows for enlarged printing of diagrams and illustrations.

Binding Type:

Digital (no physical binding)

Paper Type:

Not applicable (digital format)

Features:

Searchable text, ability to print specific pages, zoomable images.

⚙️ Engine Specifications

Engine Code:

M116 (for 380 SEC)

Engine Type:

V8, SOHC (Single Overhead Camshaft)

Displacement:

3.8 liters (3839 cc)

Horsepower:

Approximately 155-170 hp (SAE net) depending on market and specific tune.

Torque:

Approximately 210-220 lb-ft (SAE net) depending on market and specific tune.

Fuel Injection:

Bosch K-Jetronic (CIS - Continuous Injection System)

Coolant Type:

Mercedes-Benz specification coolant (e.g., G48 or equivalent ethylene glycol based)

Oil Capacity:

Approximately 8.5 US quarts (8.0 liters) with filter change.

Recommended Oil Viscosity:

SAE 15W-40 or 10W-40 (check manual for specific climate recommendations)

🔧 Transmission

Transmission Type:

4-speed Automatic Transmission (e.g., 4G-Tronic / 722.3)

Optional Transmission:

Manual transmissions were not typically offered on the W126 SEC models.

Transmission Features:

Hydraulically controlled, torque converter automatic with lock-up clutch for improved efficiency at cruising speeds. Selectable driving programs (e.g., Economy/Sport).

Transmission Fluid Type:

Mercedes-Benz Specification 236.1 or 236.6 (e.g., Dexron II or equivalent).

📐 Dimensions

Wheelbase:

2895 mm (114.0 inches)

Length:

4970 mm (195.7 inches)

Width:

1800 mm (70.9 inches)

Height:

1390 mm (54.7 inches)

Curb Weight:

Approximately 1750-1850 kg (3858-4079 lbs) depending on equipment.

Gross Vehicle Weight Rating:

Approximately 2250 kg (4960 lbs).

Standard Tire Size:

205/65VR15 or 215/60VR15

Wheel Bolt Pattern:

5x112 mm

🛡️ Safety Features

Safety Ratings:

While formal crash test ratings in the modern sense were not as standardized in 1983, Mercedes-Benz vehicles of this era were renowned for their robust construction and safety engineering, often exceeding contemporary standards.

Active Safety:

Four-wheel disc brakes, Anti-lock Braking System (ABS) available as an option, power steering, independent suspension.

Passive Safety:

Reinforced safety cage construction, energy-absorbing steering column, driver and passenger airbags (optional or introduced later in the model run, check specific vehicle), seat belts, padded interior surfaces, crumple zones.

💡 Technology Features

Infotainment System:

Premium sound system (often Becker), analog radio, cassette player. Limited by era, but of high quality for its time.

Driver Assistance Features:

Cruise control, electrically adjustable seats with memory (optional), heated seats (optional), ABS (optional).

Connectivity Features:

Not applicable in the modern sense. Features are vehicle-centric.

🔧 Maintenance

Oil Change Interval:

Typically every 10,000-15,000 km (6,000-9,000 miles) or 12 months, whichever comes first. Consult the manual for precise intervals.

Major Service Interval:

Major services usually scheduled at 30,000 km (18,000 miles) or 24 months, involving checks of all major systems, spark plugs, fuel filter, air filter, and transmission fluid/filter service.

Brake Fluid Type:

DOT 3 or DOT 4 brake fluid (refer to manual for exact specification)

Power Steering Fluid:

Mercedes-Benz Specification 236.3 (e.g., Dexron II or equivalent)

Common Issues:

Fuel distributor leaks (K-Jetronic), vacuum hose degradation, aging wiring insulation (especially around engine bay), window regulator issues, climate control system complexities, potential for rust on body panels (especially wheel arches and sills), wear in suspension bushings and ball joints, occasional idle control problems.

Filter Part Numbers Example:

Oil Filter: Mann-Filter HU 718/1 or Mercedes OEM 000 180 20 09. Fuel Filter: Mann-Filter WK 31/1 or Mercedes OEM 001 477 60 01.

📚 Vehicle History

Brand Heritage:

Mercedes-Benz has a long-standing reputation for engineering excellence, luxury, safety, and durability dating back to the late 19th century.

Model Evolution:

The W126 SEC coupe was introduced in 1981 as the two-door pillarless hardtop variant of the successful W126 S-Class sedan. It succeeded the W114/W115 C107 coupe and represented a significant advancement in luxury and technology for Mercedes-Benz coupes.

Production Years:

1981-1991

Manufacturing Location:

Sindelfingen, West Germany

🏆 Awards & Recognition

Industry Recognition:

Consistently lauded by automotive journalists and enthusiasts for its build quality, timeless design, and engineering prowess. Often cited as a benchmark for luxury coupes of its era.

Reliability Ratings:

While specific ratings from modern bodies are not applicable, the W126 platform is generally considered very robust and well-built, though maintenance can be costly due to specialized parts and labor.