🏷️ Basic Information

Make:

Mercedes-Benz

Model:

W126 SEL

Year:

1987

Chassis Code:

W126

Body Style Code:

SEL (Sonderklasse Lang - Special Class Long Wheelbase)

👋 Introduction

Target Audience:

Owners of 1987 Mercedes-Benz W126 SEL models seeking to perform maintenance, diagnostics, and repairs themselves or to better understand the procedures performed by professional mechanics.

Value Proposition:

Provides factory-level technical information identical to that used by Mercedes-Benz dealerships, ensuring accuracy and completeness. Offers significant cost savings compared to dealership labor rates and avoids generic repair information often found in aftermarket manuals.

Authenticity:

Vehicle-specific and factory-produced, ensuring the highest level of accuracy and detail.

Comprehensiveness:

Covers all repairs from A-Z for the specified model, leaving no stone unturned.

Usability:

Digital PDF format allows for easy navigation, searching, and printing of only necessary sections, preventing wear and tear on physical manuals.

📋 Manual Details

Covered Models:

All W126 SEL models for the 1987 model year, covering all engine variants and configurations.

Estimated Page Count:

Detailed specifications are not provided, but based on the comprehensive coverage described, it is expected to be an extensive manual, likely exceeding 500 pages.

Type:

Factory Service and Repair Manual

Language:

English

Digital Format:

PDF

📖 Manual Coverage

Powertrain:

Engine (M110, M116, M117 gasoline engines), Fuel System, Emission Control, Cooling System, Lube System, Ignition System, Starting and Charging System, Automatic Transmission (722.3, 722.4).

Chassis And Suspension:

Suspension (front and rear), Axles, Drive Shaft, Differential, Steering System (including power steering), Brake System (including parking brake), Wheel and Tire specifications.

Electrical And Electronics:

Complete wiring schematics, Electrical system components, Instrument panel, Lighting, Wipers and Washers, Horn, Audio/Visual systems, Cruise Control, Supplemental Restraint System (SRS) - if applicable for 1987, Door Locks, Engine Immobilizer (if equipped).

Body And Interior:

Body and Frame, Doors, Engine Hood, Exterior and Interior Trim, Glass and Mirrors, Seats, Air Conditioning System.

Maintenance:

Scheduled maintenance intervals, fluid level checks and changes, filter replacements, lubrication points.

Diagnostics And Troubleshooting:

Systematic diagnostic procedures for all major components, fault code interpretation (if applicable to 1987 systems), common problem identification and solutions.

Repair And Rebuild:

Step-by-step instructions for component removal, disassembly, inspection, repair, reassembly, and installation, including engine rebuilds, transmission overhauls, brake system repairs, suspension component replacement, and electrical system troubleshooting.

Specifications And Data:

Detailed technical specifications, torque values, clearances, fluid types and capacities, diagnostic parameters, and component identification.

Depth:

Comprehensive, covering basic maintenance to complete engine and transmission rebuilds, electrical system diagnostics, and body repairs. This manual is designed for dealership technicians and advanced DIY enthusiasts.

📊 Manual Specifications

Format:

PDF

Searchability:

Searchable text within the PDF for quick information retrieval.

Print Capability:

Fully printable, allowing users to print specific pages or sections as needed.

Image Scalability:

Diagrams and illustrations can be blown up for enlarged printing, aiding clarity in detailed procedures.

Digital Binding:

N/A (Digital format)

Digital Paper Type:

N/A (Digital format)

⚙️ Engine Specifications

Engine Options:

Likely includes the 3.0L M103 inline-6 (for 300SEL) and the 4.2L M116 or 5.0L M117 V8 engines (for 420SEL and 560SEL, respectively, though 560SEL is more common for W126 SEL). This manual should cover the specific engine(s) offered in the 1987 W126 SEL in the target market.

Horsepower Torque:

Specific figures vary by engine. For instance, a 1987 560SEL (a common SEL variant) would typically produce around 238 horsepower and 287 lb-ft of torque from its 5.0L M117 V8.

Injection System:

Bosch K-Jetronic (CIS) or KE-Jetronic (CIS-E) fuel injection systems, depending on the specific engine and market. The manual will detail the intricacies of these mechanical and electro-mechanical injection systems.

Spark Plugs:

Specific spark plug types and gap settings (e.g., Bosch W8AC or equivalent, gap typically 0.8mm) will be detailed for each engine variant.

Oil Type:

Specification for engine oil viscosity and API service classification (e.g., SAE 10W-40 or 10W-30 meeting MB 229.1 or equivalent standards) will be provided.

Coolant Type:

Mercedes-Benz approved coolant specification (e.g., G48 or equivalent) and recommended mixture ratio.

🔧 Transmission

Transmission Type:

4-speed automatic transmission (e.g., 722.3 or 722.4).

Optional Transmission:

Manual transmissions were not offered on the SEL models; only automatic was standard.

Hydraulic Control:

Detailed information on hydraulic control unit operation, adjustment, and troubleshooting of the automatic transmission.

Transmission Fluid Type:

Specification for automatic transmission fluid (e.g., ATF Dexron II or equivalent MB spec) and fluid capacity will be detailed.

Service Interval:

Recommended intervals for transmission fluid and filter change, typically around 30,000 to 50,000 miles under normal driving conditions.

📐 Dimensions

Wheelbase:

W126 SEL models feature an extended wheelbase for increased rear legroom compared to the standard W126 S-Class. For 1987, this was approximately 116.7 inches (2964 mm).

Overall Length:

Approximately 200.0 inches (5080 mm) for the SEL.

Curb Weight:

Curb weight varied by engine and options but typically ranged from approximately 3,800 to 4,200 lbs (1725 to 1905 kg).

Gross Vehicle Weight Rating:

GVWR would be specified, typically around 5,000 lbs (2268 kg).

🛡️ Safety Features

Crash Test Results:

While specific official crash test ratings from modern agencies like NHTSA may not be readily available for 1987 models, the W126 chassis was known for its robust body structure and advanced safety features for its era, including crumple zones and a reinforced passenger cell. The manual would detail the structural integrity aspects.

ABS:

Anti-lock Braking System (ABS) was available and standard on many higher-trim models by 1987, including the SEL. The manual covers ABS system operation and diagnostics.

Traction Control:

Some later models of the W126, and potentially very early introductions of traction control, might be present, but less common for '87. If equipped, the manual would cover it.

Airbags:

Driver's side airbag was an option and becoming more common by 1987. The manual details SRS system components and safety precautions.

Seat Belts:

Standard seat belts with pre-tensioners (on front belts) and potentially rear seat belt systems. The manual covers seat belt mechanisms and adjustments.

Body Construction:

High-strength steel construction, energy-absorbing steering column, and designed crumple zones.

💡 Technology Features

Audio System:

Original factory audio systems were typically high-quality AM/FM radio with cassette players, often from Becker. The manual covers removal, installation, and basic troubleshooting.

Cruise Control:

Cruise control was a common feature and its operation, adjustment, and troubleshooting are detailed in the manual.

Power Windows Locks:

Advanced power window, door lock, and seat control systems are covered comprehensively, including troubleshooting electrical faults.

Multiplex Can Communication:

While true CAN bus as we know it today wasn't prevalent, the W126 utilized early forms of multiplexed wiring and electronic control units. The manual will detail the wiring schematics and the communication pathways within the vehicle's electrical system.

🔧 Maintenance

Oil Change Interval:

Typically every 5,000 to 7,500 miles or annually, whichever comes first, depending on driving conditions and oil used. The manual will provide precise intervals.

Transmission Service Interval:

As mentioned, 30,000-50,000 miles for fluid and filter change.

Tune Up Interval:

Comprehensive tune-up recommendations, including spark plugs, air filter, and fuel filter replacement, will be detailed, often around 30,000-60,000 miles.

Brake Fluid Type:

DOT 3 or DOT 4 brake fluid specification will be listed, along with bleeding procedures.

Power Steering Fluid:

Specific power steering fluid type (often a Dexron-III equivalent or MB specific fluid) will be outlined.

Wiring Harness Degradation:

A common issue in older Mercedes models is the degradation of the engine wiring harness insulation due to age and heat. The manual will detail inspection and replacement procedures.

Fuel Accumulator Failure:

On K-Jetronic systems, fuel accumulator failure can lead to hard starting or poor performance. The manual covers diagnosis and replacement.

Climate Control System:

While advanced for its time, the automatic climate control system can develop faults in its vacuum actuators, control unit, or blower motor. The manual provides detailed troubleshooting.

📚 Vehicle History

Mercedes Benz Legacy:

Mercedes-Benz has a long-standing reputation for engineering excellence, luxury, and safety. The W126 represents a pinnacle of automotive design and engineering from the 1980s, setting benchmarks for comfort and technology.

W126 Introduction:

The W126 S-Class series was introduced in 1979 (for model year 1980) and received a significant facelift (Vorserie) in 1985, which included updated styling, improved aerodynamics, new engine options (like the M103 inline-6), and enhanced safety features. The 1987 model falls within this facelifted generation.

Sel Designation:

The 'SEL' designation signifies the long-wheelbase version of the S-Class sedan, offering significantly more rear passenger legroom and a more luxurious experience, differentiating it from the standard 'SE' models.

Production Years:

The W126 chassis was produced from 1979 to 1991. The 1987 model year is part of the second half of its production run.

🏆 Awards & Recognition

Industry Awards:

The W126 chassis, in general, received numerous accolades during its production run for its design, engineering, and luxury. It was widely regarded as one of the finest luxury sedans of its era.

Consumer Reports Rankings:

While specific 1987 ratings are historical, Consumer Reports consistently ranked Mercedes-Benz vehicles highly for their build quality and comfort, though sometimes noted complexity of repairs.

Manufacturer Endorsement:

This manual is a factory document, meaning it is the definitive guide approved and used by Mercedes-Benz technicians, guaranteeing its authenticity and authority.