Model Segment:
Full-size luxury sedan and coupe.
Key Competitors:
BMW 7 Series, Audi V8, Jaguar XJ, Cadillac DeVille, Lincoln Town Car.
W126 Distinction:
Renowned for its build quality, comfort, safety innovations (for its era), and elegant styling. Represented Mercedes-Benz's flagship offering during the 1980s.
Manual Content Summary:
Comprehensive workshop and service repair coverage for Mercedes-Benz W126 models, including engine, electrical systems, maintenance, owner information, climate control, and body/chassis.
Estimated Page Count:
Highly comprehensive, likely exceeding 1000 pages when all modules are combined. Specific page counts vary by the original factory manuals.
Manual Type:
Workshop Service Repair Manual
Language:
English (Assumed, typical for comprehensive workshop manuals of this era for international markets)
Engine Systems:
Detailed diagnostics, repair procedures, component testing, timing adjustments, fuel injection (K-Jetronic, KE-Jetronic), emissions control, cooling system, lubrication system, engine overhaul.
Electrical Systems:
Wiring diagrams for all vehicle circuits, component testing, troubleshooting guides, fuse/relay locations, ABS, SRS (Airbag), power windows, central locking, lighting, instrument cluster, engine control unit (ECU).
Climate Control:
Manual and automatic climate control systems (e.g., THERMATIC, THERMOTRONIC), A/C system operation, refrigerant handling, blower motor, HVAC controls, ducting, leak detection.
Body Chassis:
Suspension (front and rear), steering system, braking system (including ABS), drivetrain, exhaust system, body panels, doors, windows, locks, interior trim, bumpers, structural components.
Maintenance Procedures:
Scheduled maintenance intervals, oil and filter changes, fluid checks and replacements (coolant, brake fluid, power steering fluid, transmission fluid), spark plug replacement, filter replacement, belt inspection and replacement.
Diagnostic Procedures:
Step-by-step troubleshooting for common and complex issues, symptom-based diagnosis, component testing using multimeter and specialized tools, fault code reading (where applicable).
Repair Procedures:
Detailed instructions for component removal, installation, and repair for all major systems, including engine rebuilds, transmission overhauls, brake caliper replacement, suspension component replacement, electrical component repair.
Depth Of Coverage:
Extremely detailed, covering everything from basic fluid changes and pre-delivery inspections to complete engine and transmission overhauls, advanced electrical diagnostics, and bodywork repairs. Suitable for professional technicians and experienced DIY enthusiasts.
Transmission Type:
Typically 4-speed automatic transmission (e.g., 722.3, 722.4, 722.5).
Manual Transmission Availability:
Rarely offered and generally not documented in typical workshop manuals for these luxury models.
Automatic Transmission Features:
Hydraulic torque converter, electronic or vacuum modulation for shift points, some models featured a 'Sport'/'Economy' mode selector.
Wheelbase:
Varies by model: Long wheelbase (SEL/SDL) approx. 116.7 inches; Standard wheelbase (SE/SD/SEC) approx. 112.8 inches.
Overall Length:
Varies by model: Long wheelbase models are significantly longer.
Curb Weight Range:
Approximately 3,500 lbs to 4,200 lbs, depending on engine and body style.
Wheel Bolt Pattern:
5x112
Wheel Offset Range:
ET 23 to ET 35 (common)
Era Safety Features:
While formal crash test ratings were less standardized than today, the W126 was considered exceptionally safe for its time, featuring a reinforced passenger cell, crumple zones, and significant engineering focused on occupant protection.
Active Safety Systems:
Anti-lock Braking System (ABS) became widely available, power-assisted steering, advanced brake hydraulics.
Passive Safety Features:
Driver and passenger airbags (SRS) introduced on later models (post-1985/1986), padded interior surfaces, three-point seatbelts, safety steering column.
Audio Systems:
Original premium sound systems (e.g., Becker), cassette players, AM/FM radio. Later models might feature early CD changers.
Early Driver Aid:
Cruise control, power adjustable seats with memory, automatic climate control, limited-slip differential (optional).
Original Connectivity:
No modern connectivity features like Bluetooth or USB. Antennas were for radio reception only.
Headlight Type:
Halogen headlights standard, some later models offered optional Xenon HID lighting in certain markets.
Oil Change Interval:
Typically every 7,500 to 10,000 miles or 12 months, whichever comes first, depending on driving conditions and specific engine.
Major Service Intervals:
Spark plugs, transmission fluid, coolant, brake fluid typically at 30,000 to 60,000-mile intervals.
Engine Oil:
e.g., Mobil 1 15W-40 or 10W-40 (diesel), 5W-40 or 10W-40 (gasoline), SAE 30 for some older diesel applications. Refer to manual for exact spec (MB-Approval 229.1 or equivalent).
Coolant:
MB-Approved Antifreeze/Coolant (e.g., G05 or G05+), typically a 50/50 mix with distilled water.
Transmission Fluid:
e.g., MB 236.14 (for later 5-speed transmissions), MB 236.7 or equivalent ATF (for 4-speed transmissions).
Brake Fluid:
DOT 3 or DOT 4, MB-Approval 331.0 or equivalent.
Common W126 Concerns:
Vacuum leaks affecting central locking and idle control, biodegradable wiring harnesses (requiring replacement), fuel distributor issues (K-Jetronic), differential seal leaks, ABS sensor failures, climate control actuator failures, rust in common areas (wheel wells, rocker panels, sunroof drains).
Diesel Specific Issues:
Glow plug failure, injection pump wear, turbocharger issues on later models, carbon buildup.
Mercedes Benz Legacy:
The W126 built upon Mercedes-Benz's reputation for engineering excellence, durability, and luxury, succeeding the W116 S-Class.
W126 Generations:
The W126 was produced in two distinct phases: early models (1981-1985) and facelifted models (1986-1991), which featured updated styling, improved aerodynamics, and new engine options (e.g., the M117 5.6L V8 and the 300SDL turbodiesel).
Manufacturing Locations:
Primarily Sindelfingen, Germany.
Production Volume:
Over 800,000 units produced globally, making it a successful flagship model.
Historical Acclaim:
Consistently ranked among the best luxury sedans of its era by automotive journalists for comfort, engineering, and safety. Often cited as a benchmark for build quality and longevity.
Consumer Reports Era:
While specific ratings are difficult to pinpoint for every year, Consumer Reports and similar publications generally praised the W126's reliability and comfort, though maintenance costs were noted as higher than average.
Iso Standards Era:
Manufactured under stringent quality control processes typical of Mercedes-Benz, adhering to German automotive engineering standards.
