🏷️ Basic Information

Make:

Mercedes-Benz

Model:

500SEL

Year:

1984

Chassis Code:

W126

Engine Code:

M117

👋 Introduction

Positioning:

The Mercedes-Benz 500SEL (W126) represented the pinnacle of luxury and engineering in the early 1980s, offering unparalleled comfort, performance, and build quality for discerning buyers. It was a direct competitor to other high-end sedans from brands like BMW and Jaguar.

Competitors:

Primary competitors included the BMW 7 Series (E23), Jaguar XJ-S (though often considered more of a grand tourer), and Cadillac Seville. The 500SEL excelled in its blend of sophisticated engineering, robust build, and refined driving experience.

Features:

Long-wheelbase offering increased rear legroom, powerful V8 engine, advanced (for the era) suspension and braking systems, premium interior materials, and a reputation for durability and longevity.

📋 Manual Details

Coverage:

Complete Service and Repair

Page Count:

Approximately 1000+ pages (typical for comprehensive factory-style manuals)

Manual Type:

Factory Service Manual / Repair Manual

Language:

English

Format:

Digital (PDF)

Source Type:

Likely a reproduction of official Mercedes-Benz factory service documentation.

📖 Manual Coverage

Engine Mechanical:

Engine removal/installation, cylinder head, piston, crankshaft, camshaft, timing system, lubrication system, cooling system, fuel system (injection system components), exhaust system.

Engine Management:

Bosch KE-Jetronic fuel injection system, ignition system, emission control systems, diagnostic procedures, sensor and actuator testing.

Transmission:

Automatic transmission (4-speed 722.3) overhaul, troubleshooting, fluid specifications, torque converter, shift controls.

Drivetrain:

Driveshaft, universal joints, rear axle assembly, differential, wheel bearings, axle shafts.

Suspension:

Front and rear suspension components, shock absorbers, springs, control arms, bushings, steering linkage, power steering system (hydraulic). Includes components for self-leveling rear suspension (if equipped).

Brakes:

Hydraulic brake system, ABS (Anti-lock Braking System) components and diagnostics, brake calipers, master cylinder, brake lines, brake fluid specifications, parking brake.

Steering:

Power steering system operation, troubleshooting, steering gear, steering column, steering wheel.

Electrical System:

Battery, starter, alternator, lighting system (headlights, taillights, interior), fuses, relays, wiring diagrams, instrument cluster, ignition switch, power windows, power seats, central locking, sunroof operation.

HVAC:

Heating, ventilation, and air conditioning (HVAC) system components, refrigerant types, charging procedures, troubleshooting, blower motor, climate control unit.

Body:

Exterior body panels, doors, hood, trunk lid, bumpers, glass, seals, interior trim, sound deadening, body repair procedures.

Chassis:

Frame structure, mounting points, corrosion protection.

Maintenance:

Scheduled maintenance intervals, oil changes, filter replacements (oil, air, fuel), spark plug replacement, coolant flush and fill, brake fluid replacement, transmission fluid and filter change, differential fluid change, lubrication points.

Diagnostics:

Troubleshooting charts and flowcharts for common problems, symptom-based diagnostics, component testing procedures, diagnostic connector identification and use.

Repair:

Step-by-step repair procedures for all major mechanical and electrical components, including engine rebuilds, transmission overhauls, suspension and brake component replacement, electrical component repair and replacement.

Adjustment:

Valve adjustments, ignition timing adjustments, idle speed adjustments, fuel injection system adjustments (where applicable), parking brake adjustments.

Wiring Diagrams:

Detailed electrical wiring diagrams for all vehicle systems, including engine management, lighting, power accessories, and diagnostics.

Specifications:

Torque specifications for all fasteners, fluid capacities, electrical system voltages, diagnostic trouble codes (DTCs) with explanations.

Depth:

Comprehensive: Covers everything from basic maintenance and fluid checks to complete engine and transmission overhauls, complex electrical diagnostics, and bodywork repair.

📊 Manual Specifications

File Format:

Searchable PDF with indexed chapters for easy navigation.

Print Quality:

High-resolution scans ensuring clear diagrams, text, and illustrations.

Binding Type:

N/A (Digital Format)

Paper Type:

N/A (Digital Format)

Completeness Level:

This is a comprehensive service and repair manual, designed for professional technicians and serious DIY enthusiasts. It provides detailed instructions for maintenance, troubleshooting, diagnostics, and repair of all major vehicle systems.

⚙️ Engine Specifications

Engine Type:

V8, SOHC

Displacement:

5.0 Liters (4973 cc)

Bore X Stroke:

96.0 mm x 85.0 mm

Compression Ratio:

8.3:1

Engine Code Family:

M117 E50

Horsepower:

Approximately 228 hp (168 kW) at 4750 rpm (DIN rating)

Torque:

Approximately 287 lb-ft (390 Nm) at 3250 rpm (DIN rating)

Fuel Delivery:

Bosch KE-Jetronic Continuous Injection System (CIS-E)

Fuel Type:

Unleaded gasoline, 91 octane or higher recommended

Ignition Type:

Electronic Ignition (CDI)

Oil Capacity:

8.0 Liters (approx. 8.5 US quarts) with filter

Coolant Capacity:

11.0 Liters (approx. 11.6 US quarts)

🔧 Transmission

Transmission Type:

4-speed Automatic (722.3)

Transmission Features:

Lock-up torque converter, electronic control of shift points (later models had improved control), selectable 'Economy'/'Sport' modes.

Transmission Fluid Type:

MB 236.6 (or equivalent Dexron II/III for compatible transmissions, consult manual for exact specification)

Transmission Fluid Capacity:

Approximately 7.5 Liters (7.9 US quarts) for complete fill, 3.5 Liters for pan drop and filter change.

📐 Dimensions

Wheelbase:

3085 mm (121.5 inches)

Length:

5025 mm (197.8 inches)

Width:

1798 mm (70.8 inches)

Height:

1438 mm (56.6 inches)

Curb Weight:

Approximately 1800 kg (3968 lbs)

Gross Vehicle Weight Rating:

2350 kg (5181 lbs)

🛡️ Safety Features

Crash Testing Era:

Early 1980s safety standards. While official NHTSA ratings are not as detailed as modern standards, the W126 was considered exceptionally safe for its time.

ABS:

Available Anti-lock Braking System (ABS) as an option on some models.

Airbags:

Driver's side airbag introduced as an option in 1986 and became standard later. Not standard on all 1984 models.

Seatbelts:

Three-point inertia-reel seatbelts in the front and rear.

Chassis Design:

Reinforced passenger cell, crumple zones, and energy-absorbing steering column.

💡 Technology Features

Audio System:

Optional Becker AM/FM stereo with cassette player, often with premium speaker options.

Climate Control:

Automatic climate control (optional on some models, standard on SEL) offering precise temperature management.

Cruise Control:

Standard cruise control system.

Memory Seats:

Optional power-adjustable front seats with memory functions.

Antennae:

Power-operated retractable antenna.

🔧 Maintenance

Oil Change Interval:

Every 15,000 km (9,300 miles) or 12 months, whichever comes first. (Consult manual for specific grade of oil and driving conditions).

Air Filter Replacement:

Every 30,000 km (18,600 miles) or as needed based on driving environment.

Fuel Filter Replacement:

Every 30,000 km (18,600 miles) for CIS-E systems.

Spark Plug Replacement:

Typically every 20,000 - 30,000 km (12,500 - 18,600 miles), depending on plug type (e.g., standard vs. platinum).

Transmission Fluid Filter:

Every 60,000 km (37,000 miles) or 2-3 years.

Engine Oil:

API SG or higher, SAE 10W-40 or 15W-50 depending on climate. (Always consult the manual for the exact specification).

Coolant:

Mercedes-Benz approved coolant or equivalent (e.g., G05 or similar), mixed 50/50 with distilled water.

Brake Fluid:

DOT 3 or DOT 4.

Wiring Harness Degradation:

Degradation of insulation on the engine wiring harness (especially around heat sources) leading to short circuits and erratic engine behavior. The manual will detail diagnosis and replacement procedures.

Fuel Accumulator Failure:

The fuel accumulator, part of the KE-Jetronic system, can fail, leading to hard starting, especially when hot. The manual will cover testing and replacement.

Heater Control Valve:

Failure of the vacuum-operated heater control valves can result in poor cabin temperature control. The manual provides troubleshooting for the vacuum system.

Suspension Bushings:

Wear in control arm and subframe bushings can lead to poor handling and noise. The manual details inspection and replacement.

ABS Sensor Failure:

Early ABS systems can be prone to sensor or control unit failures. The manual outlines diagnostic steps.

📚 Vehicle History

Heritage:

Mercedes-Benz has a long-standing reputation for engineering excellence, safety, and luxury, dating back to the invention of the automobile. The S-Class lineage represents the flagship sedan of the brand.

W126 Era:

The W126 chassis succeeded the W116 S-Class and was produced from 1979 to 1991. The 1984 model year falls within the initial production phase. The W126 was a significant evolution, offering improved aerodynamics, lighter construction, and enhanced safety and comfort features.

Facelift Elements:

The W126 received a significant facelift in 1985 (for the 1986 model year), introducing revised bumpers, exterior trim, and interior upgrades, along with engine enhancements. The 1984 model predates these major visual changes.

Production Years:

1979-1991

Manufacturing Location:

Sindelfingen, West Germany

🏆 Awards & Recognition

General Recognition:

While specific awards for the 1984 model are not widely documented in the same way as modern vehicles, the W126 generation of the S-Class consistently received praise from automotive journalists and industry experts for its luxury, build quality, and engineering prowess throughout its production run. It was widely regarded as one of the finest sedans in the world during its era.