Vehicle Segment:
Full-size luxury sedan, representing the pinnacle of Mercedes-Benz engineering and comfort in its era.
Competitive Set:
Competed directly with other high-end luxury sedans such as the BMW 7 Series, Jaguar XJ, Audi V8, and Cadillac Fleetwood.
Luxurious Appointments:
Extended wheelbase (SEL) provided significantly increased rear legroom and comfort, premium interior materials, advanced features for the time.
Engineering Excellence:
Renowned for its robust build quality, advanced engineering, and sophisticated ride and handling characteristics.
User Advantage:
Enables owners and independent technicians to perform accurate diagnostics, maintenance, and repairs, reducing reliance on expensive dealership services.
Primary Coverage:
All models and all repairs A-Z for the 1990 Mercedes-Benz W126 SEL
Specific Models Covered:
1990 W126 SEL variants (e.g., 300SEL, 420SEL, 560SEL depending on market availability for that year)
Estimated Page Count:
Varies by specific factory publication, but comprehensive manuals for this era typically range from 1000-2500 pages when compiled.
Type:
Factory Service and Repair Manual
Engine Systems:
Engine mechanical, fuel injection (KE-Jetronic or electronic variants), ignition, lubrication, cooling, emission controls, engine control unit (ECU).
Drivetrain Systems:
Automatic transmission (e.g., 4-speed 722.3, 5-speed 722.4/722.6 depending on engine variant), differential, drive shafts, axles, suspension (front and rear independent), steering (power steering).
Braking Systems:
Hydraulic brake system, ABS (Anti-lock Braking System), parking brake, brake control.
Electrical Systems:
Complete electrical schematics, wiring diagrams, battery, charging system, starting system, lighting, instruments, power windows, power seats, central locking, cruise control, air conditioning controls, audio system, supplementary restraint system (SRS) wiring.
Body And Chassis:
Body construction, exterior trim, interior trim, doors, hood, glass, mirrors, instrument panel, seats, windshield wipers and washers.
Maintenance Procedures:
Regular scheduled maintenance, fluid changes (oil, coolant, brake fluid, transmission fluid), filter replacements, tune-ups, lubrication points.
Diagnostic Procedures:
Troubleshooting guides, diagnostic flowcharts, symptom analysis for common and uncommon issues.
Repair Procedures:
Component removal and installation, overhaul procedures for major systems (engine, transmission), body panel repair, electrical component replacement.
Adjustment And Calibration:
Fuel system adjustments, ignition timing (where applicable), suspension alignment specifications, brake system bleeding and adjustment.
Depth Of Information:
Factory-level technical detail for dealership technicians, covering all aspects from basic maintenance to complex diagnostics and complete component rebuilds.
Diagrams And Illustrations:
Extensive use of line drawings, exploded views, and detailed illustrations for component identification and assembly/disassembly guidance.
Wiring Schematics:
Complete and detailed wiring diagrams for all vehicle electrical systems, color-coded and broken down by function and circuit.
Specification Data:
Comprehensive listing of all torque specifications, clearances, fluid capacities, electrical values, and measurement tolerances.
Searchability:
Likely to be text-searchable PDF (OCR processed) for easy navigation.
Print Capability:
Fully printable, allowing users to print specific pages or sections as needed.
Image Resolution:
High resolution, allowing for magnification of diagrams and illustrations for detailed viewing.
Binding Type:
Digital (PDF) - no physical binding
Paper Type:
Digital (PDF) - no physical paper type
Engine Type:
V8 SOHC (depending on specific SEL model for 1990, typically 4.2L or 5.6L)
Engine Displacement:
Commonly 4196cc (420SEL) or 5549cc (560SEL). Check specific model for exact displacement.
Horsepower Output:
Approximately 201 hp (420SEL) to 238 hp (560SEL) DIN, depending on market and specific engine variant.
Torque Output:
Approximately 320 Nm (420SEL) to 385 Nm (560SEL) DIN, depending on market and specific engine variant.
Fuel Delivery:
Bosch KE-Jetronic (CIS-E) fuel injection or similar electronic fuel injection systems.
Fuel Recommendation:
Unleaded gasoline, octane rating as specified by manufacturer (typically 91+ RON).
Coolant Type:
Ethylene glycol-based coolant with corrosion inhibitors. Specific Mercedes-Benz approved coolant recommended.
Crash Test Information:
While official government ratings were less common in the US for this era, the W126 was known for its robust safety cage and crumple zones, setting high standards for passive safety.
Airbags:
Driver's airbag was standard on most 1990 W126 models.
Seat Belts:
Front and rear seat belts, often with pre-tensioners for front occupants.
ABS:
Anti-lock Braking System (ABS) was standard or widely available.
Traction Control:
Some models may have featured ASR (Anti-Slip Regulation) traction control.
Oil Change Interval:
Typically every 15,000 km (9,000 miles) or annually, whichever comes first, using synthetic oil. Specifics in manual.
Transmission Fluid Service:
Recommended every 60,000 km (37,000 miles) or as per manual's specific guidance for the transmission type.
Engine Oil Type:
Synthetic engine oil, viscosity grade like 0W-40, 5W-40, or 10W-40 depending on climate, meeting MB 229.1 or later specifications.
Brake Fluid Type:
DOT 3 or DOT 4 hydraulic brake fluid.
Common Wear Items:
Timing chain guides (on M117/M119 engines), fuel distributor seals, SRS warning light (faulty occupant classification sensor or wiring), door seal degradation, idle control valve issues.
Electrical Quirks:
Vacuum leaks affecting central locking and climate control, window regulator failures, dashboard warning lights.
