Positioning:
The definitive resource for maintaining and repairing the iconic Mercedes-Benz W126 S-Class, catering to both enthusiastic owners and professional technicians.
Advantage:
Provides comprehensive, factory-level detail often missing in third-party publications, ensuring accuracy and completeness for all W126 variants across a broad production span.
Content Highlight:
Covers every aspect of the vehicle from routine maintenance to complex engine and transmission rebuilds, backed by detailed illustrations and factory specifications.
Cost Savings:
Enables owners to perform repairs and maintenance themselves, significantly reducing labor costs associated with dealership servicing.
Model Variants Covered:
300 SD, 300 SDL, 300 SE, 300 SEL, 350 SD, 350 SDL, 380 SE, 380 SEL, 380 SEC, 420 SEL, 500 SEL, 500 SEC, 560 SEL, 560 SEC
Type:
Complete Official Service and Repair Manual
Powertrain:
Engine overhaul and rebuilding, transmission removal and installation, transmission in-car servicing, engine performance, firing orders, serpentine belt routings with diagrams, timing belt service procedures.
Chassis:
Brakes, sunroof, front end and alignment procedures and specifications, suspension, U-joint and CV-joint service procedures, vacuum diagrams.
Electrical:
Wiring diagrams, computer diagnostic trouble tree charts, computer diagnostic codes.
Comfort And Convenience:
Air conditioning service and capacities.
Body And Frame:
Includes body repair, panel replacement, door and window mechanisms, convertible top mechanisms (if applicable to specific variants not explicitly listed, but generally covered in broad chassis work).
Maintenance:
Factory maintenance schedules and charts, driving concerns.
Diagnostics And Repair:
Trouble codes, troubleshooting and diagnostics, detailed illustrations, diagrams, wiring schematics, step-by-step instructions, complete torque specifications, repair procedures.
Troubleshooting Guides:
Specific troubleshooting flowcharts and diagnostic tree charts for common issues.
Depth:
Complete disassembly, rebuild, refurbishment, restoration, advanced diagnostics, and repair procedures suitable for both DIY and professional mechanics.
Illustrations And Diagrams:
Hundreds of detailed illustrations, exploded diagrams, and drawings guide users through procedures.
Torque Specs:
Comprehensive torque specifications for all major fasteners, crucial for correct assembly and preventing damage.
Engine Options:
Inline-5 Diesel (OM617, OM603), V8 Gasoline (M116, M117)
Displacement Range:
2.9L (300 SD/SDL) to 5.6L (560 SEL/SEC)
Horsepower Range:
Approximately 136 hp (300 SD) to 227 hp (560 SEC/SEL)
Diesel Injection:
Bosch inline injection pumps (OM617), Bosch inline injection pumps with EDC (OM603)
Gasoline Injection:
Bosch K-Jetronic (CIS), Bosch KE-Jetronic (CIS-E)
Valve Train:
Overhead camshaft (OHC) for OM603, Overhead camshaft (OHC) with rocker arms for M116/M117
Cooling System:
Pressurized, glycol-based coolant system with belt-driven fan or viscous coupling fan.
Engine Management:
Engine control units (ECUs) for gasoline models, managing fuel injection, ignition timing, and idle speed control.
Transmission Type:
4-speed automatic transmission (e.g., 722.3, 722.4, 722.5)
Manual Transmission:
Rarely offered, primarily on earlier European models, not typically specified for North American market coverage within this manual's scope.
Torque Converter:
Lock-up torque converter for improved fuel efficiency.
Atf Type:
MB 236.2 or MB 236.3 (Dexron II compatible, check specific model year)
Crash Test History:
W126 models were designed to high safety standards for their era, including crumple zones and robust passenger cell construction. Specific ratings are not readily available in a standardized modern format.
ABS:
Anti-lock Braking System (ABS) available on many models, standard on later versions.
Airbags:
Driver's side airbag introduced as an option in later years, becoming standard on most models by the end of production.
Seatbelts:
Pre-tensioning front seatbelts on later models.
Audio System:
Factory-installed AM/FM stereo cassette systems, often with optional amplifiers and premium speaker packages. Early models featured analog tuning, later models introduced digital tuning.
Cruise Control:
Standard on most models, a sophisticated (for its time) electronic cruise control system.
Tele Aid:
Not applicable for this era of vehicles.
HVAC System:
Fully automatic climate control (THERMATIC on some models, THERMOTRONIC on higher trims) with sophisticated vacuum-actuated blend doors and blower control.
Oil Change:
Typically every 10,000 km or 6 months, whichever comes first. Consult specific manual section for diesel vs. gasoline engines.
Major Service:
Includes spark plugs, fuel filters, air filters, coolant change, transmission service. Intervals vary by component and mileage (e.g., 60,000 km for spark plugs on some gasoline engines).
Engine Oil:
API SG or higher, SAE 10W-40 or 15W-40 (check owner's manual for specific viscosity based on ambient temperature). For diesel, specific diesel-rated oils are required.
Coolant:
Mercedes-Benz approved coolant (e.g., G48 or similar blue/green ethylene glycol based) with a 50/50 mix with distilled water for freeze protection and corrosion inhibition.
Brake Fluid:
DOT 4 recommended.
Power Steering Fluid:
MB 235.6 or equivalent ATF (check specific model).
Common Problems:
Vacuum system leaks affecting central locking, climate control, and door locks; biodegrading wiring insulation (especially in later models); head gasket issues on some gasoline engines; diesel glow plug system failures; suspension component wear (bushings, ball joints); window regulator failures.
Preventative Maintenance:
Regularly inspect and replace vacuum hoses; address fuel system maintenance (filters); monitor engine coolant levels and condition; service transmission fluid and filter at recommended intervals.
Heritage Context:
Part of Mercedes-Benz's legacy of producing high-quality, luxurious, and technologically advanced sedans and coupes. Known for exceptional build quality and longevity.
Generation:
Second generation S-Class (W126), succeeding the W116 and preceding the W140. Characterized by updated styling and aerodynamics.
Production Period:
1979-1991 (W126/C126)
Key Milestones:
Introduction of airbags, improved fuel efficiency through aerodynamic design and engine management, introduction of the diesel models for the US market.
Industry Acclaim:
The W126 S-Class was widely lauded for its comfort, refinement, engineering, and safety, often considered the benchmark for luxury sedans of its era.
Safety Perception:
Perceived as one of the safest vehicles of its time due to its robust construction and advanced (for the era) safety features.
