🏷️ Basic Information

Make:

Mercedes-Benz

Model:

W126 SEL

Year:

1986

Chassis Code:

W126

Body Style Code:

V126 (Long Wheelbase)

👋 Introduction

Positioning:

Targeted at owners and independent repair shops seeking authoritative, dealership-level repair information for the W126 SEL.

Competitors:

Aftermarket repair manuals (Haynes, Chilton) which may lack the depth and accuracy of factory publications. Generic online repair databases.

Uniqueness:

Vehicle-specific, factory-issued data, providing exact procedures and specifications used by Mercedes-Benz technicians. Eliminates generic information.

Convenience:

Single, easy-to-use PDF format, searchable, printable for workshop use, reduces the need for physical manuals.

📋 Manual Details

Coverage Scope:

All W126 SEL models for 1986, all repairs A-Z

Estimated Page Count:

Varies by specific model and engine variant, but extensive, likely exceeding 1000 pages for comprehensive coverage.

Type:

Factory Service and Repair Manual

Language:

English

Format:

Digital (PDF)

📖 Manual Coverage

Engine Mechanical:

Engine assembly, cylinder head, valve train, crankshaft, pistons, connecting rods, lubrication system, cooling system, fuel system (including injection), intake and exhaust systems, emissions control systems.

Engine Control:

Engine control unit (ECU) diagnostics, sensor testing, actuator testing, ignition system, starting and charging system, fuel injection system control.

Transmission:

Automatic transmission overhaul, service, diagnostics, fluid specifications, hydraulic control, torque converter.

Drivetrain:

Drive shaft, universal joints, differential, axle shafts, wheel bearings.

Suspension:

Front and rear suspension components, shock absorbers, springs, control arms, bushings, height-adjustable suspension (if applicable).

Brakes:

Hydraulic brake system, brake calipers, brake discs, brake pads, master cylinder, power brake booster, ABS (Anti-lock Braking System) diagnostics and repair, parking brake system.

Steering:

Steering column, power steering system, steering gear, tie rod ends, steering linkage, steering angle sensor.

Electrical:

Complete electrical system diagnosis, wiring schematics, lighting system, battery, alternator, starter, fuses, relays, multiplex communication systems, CAN communication (if applicable).

Climate Control:

Air conditioning system service, refrigerant handling, compressor, condenser, evaporator, climate control unit, heater core, blower motor.

Interior And Exterior:

Door locks, windows, mirrors, seats, seat belts, airbags (Supplemental Restraint System), instrument panel, meters, audio system, cruise control, wipers and washers, windshield and glass, engine hood, doors, exterior and interior trim.

Maintenance:

Scheduled maintenance intervals, oil changes, filter replacements, fluid checks and changes, spark plug replacement, belt replacement, brake fluid flush.

Troubleshooting:

System-specific diagnostic procedures, common fault identification, symptom-based troubleshooting guides, error code interpretation.

Repair And Rebuild:

Step-by-step repair instructions for all major vehicle systems, engine rebuild procedures, transmission overhaul, brake system repair, suspension component replacement, electrical component repair.

Diagnostics:

On-board diagnostics (OBD) procedures (where applicable for the era), electrical system testing, mechanical system testing, fuel system pressure testing.

Installation:

Component replacement and installation procedures for all major parts and systems.

Depth:

Factory-level, comprehensive, covering routine maintenance to complete engine and transmission rebuilds, including detailed electrical schematics and diagnostic procedures.

📊 Manual Specifications

Format:

PDF

Compatibility:

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

Requirements:

Adobe PDF Reader, Winzip (free online)

Printability:

All pages printable, allows for enlargement of images and diagrams

Binding:

Digital (no physical binding)

Paper Type:

N/A (Digital)

⚙️ Engine Specifications

Engine Type:

M117 (V8 SOHC)

Displacement:

5.0 Liter (approx. 4973 cc)

Bore X Stroke:

96.5 mm x 85.0 mm

Compression Ratio:

8.0:1 or 8.3:1 (depending on market and emissions configuration)

Horsepower:

Approx. 180-230 hp (depending on market and specific tuning)

Torque:

Approx. 235-280 lb-ft (depending on market and specific tuning)

Fuel Injection:

Bosch K-Jetronic (CIS) or CIS-Jetronic fuel injection

Fuel Type:

Unleaded gasoline (Premium)

Ignition System:

Electronic ignition with distributor and spark control unit

Cooling System:

Pressurized liquid cooling system

Oil Type Specification:

MB 229.1 compliant oil (e.g., SAE 15W-40 or 10W-40)

🔧 Transmission

Transmission Type:

4-speed automatic (722.3 series)

Transmission Type:

Not applicable for SEL models, standard automatic

Transmission Fluid:

MB 236.3 or Dexron II (check specific manual for exact recommendation)

Gear Ratios:

Detailed ratios provided within the manual.

📐 Dimensions

Wheelbase:

3085 mm (121.5 inches)

Overall Length:

5210 mm (205.1 inches)

Overall Width:

1790 mm (70.5 inches)

Overall Height:

1440 mm (56.7 inches)

Curb Weight:

Approx. 1800-1900 kg (3968-4189 lbs)

Gross Vehicle Weight:

Varies by configuration, detailed in manual.

Wheel Bolt Pattern:

5x112 mm

Standard Tire Size:

205/65R15 or 215/60R15

🛡️ Safety Features

Crash Test Results:

Information not readily available for this specific model year from public databases, but Mercedes-Benz built these vehicles to high safety standards for their era.

ABS:

Anti-lock Braking System (ABS) available as optional or standard depending on market.

Airbags:

Driver's side airbag became available in later W126 models, potentially optional for 1986. Passenger airbags were not standard or widely available in this model year.

Seat Belts:

Three-point inertia-reel seat belts for front and rear occupants.

Body Structure:

Reinforced safety cage, crumple zones.

💡 Technology Features

Audio System:

Factory-installed AM/FM radio with cassette player, often with power antenna and upgraded speaker systems.

Instrument Panel:

Comprehensive analog gauges for speed, RPM, fuel level, coolant temperature, oil pressure, and various warning lights.

Cruise Control:

Standard or optional cruise control system for highway driving.

Multiplex Communication:

Early forms of multiplexed wiring were used to reduce complexity, and the manual details these systems. The 'Multiplex/CAN Communication' section in the product description hints at this, though full CAN bus as we know it today was not prevalent.

🔧 Maintenance

Oil Change Interval:

Typically every 7,500-10,000 miles or annually, whichever comes first, depending on driving conditions and oil used. Refer to manual for specifics.

Transmission Fluid Change:

Recommended every 30,000-50,000 miles or as specified in the manual.

Spark Plug Replacement:

Approximately every 30,000 miles.

Engine Coolant:

Glysantin G48 or equivalent silicate-free coolant mixed with distilled water (50/50 ratio).

Brake Fluid:

DOT 3 or DOT 4 brake fluid.

Wiring Harness:

Aging wiring harnesses, particularly in the engine bay, can degrade leading to electrical issues. The manual details testing and replacement procedures.

Climate Control Hoses:

Air conditioning hoses and seals can degrade over time, leading to refrigerant leaks. The manual covers diagnosis and replacement.

Fuel Injector Seals:

Fuel injector seals on K-Jetronic systems can harden, causing fuel leaks or poor running. The manual details their replacement.

Window Regulators:

Power window regulators can fail due to wear on the cables and motors. The manual provides repair instructions.

Subframe Mounts:

Rubber subframe mounts can degrade, leading to vibrations and clunking noises. Replacement procedures are detailed.

📚 Vehicle History

Heritage:

Mercedes-Benz is renowned for its engineering excellence, luxury, and safety innovations throughout its history.

W126 Development:

The W126 S-Class was introduced in 1979 as the successor to the W116. It represented a significant advancement in aerodynamic design, safety, and luxury features. The SEL designation signifies the long-wheelbase version.

W126 Facelift:

The W126 underwent a significant facelift in 1985, which included aerodynamic improvements, revised bumpers, larger side moldings, and engine updates. The 1986 model falls into this post-facelift generation.

Production Years:

1979-1991 (W126 platform)

Manufacturing Locations:

Germany (primarily Sindelfingen)

🏆 Awards & Recognition

Automotive Journalism:

The W126 generation of the S-Class consistently received high praise from automotive journalists for its refinement, build quality, and engineering. It was considered a benchmark for luxury sedans of its era.