Vehicle Segment:
Mid-size Luxury/Executive Sedan and Estate, renowned for durability and engineering.
Contemporary Competitors:
BMW 5 Series (E28), Audi 100, Volvo 240 series, and other European luxury sedans of the era.
Model Reputation:
The W123 is widely celebrated for its robust build quality, exceptional longevity, and the reliable OM617 diesel engine, often cited as one of Mercedes-Benz's finest engines.
Cost Effectiveness:
An inexpensive way to maintain and repair the vehicle, empowering owners to perform tasks themselves and save on dealership service costs.
Covered Years:
1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985
Body Styles Covered:
Sedan, Coupe, Wagon (Estate/T-Model), potentially others depending on manual's scope
Estimated Page Count:
Likely 800+ pages, typical for comprehensive workshop manuals of this era.
Manual Type:
Workshop Service and Repair Manual
Engine Management:
Detailed diagnosis and repair of the OM617 TurboDiesel engine, including fuel injection system, turbocharger, glow plug system, and cooling system.
Drivetrain:
Coverage of manual and automatic transmissions, clutch, driveshafts, differential, and axles.
Suspension Steering:
Front and rear suspension components, shock absorbers, springs, control arms, steering gear, power steering system, and wheel alignment procedures.
Brakes:
Hydraulic brake system, including front and rear disc brakes, brake calipers, master cylinder, brake lines, parking brake, and ABS diagnostics (if equipped on later models).
Electrical System:
Comprehensive wiring diagrams, battery, charging system (alternator), starting system, lighting system, ignition system, instrument cluster, power windows, and other electrical accessories.
Body And Chassis:
Body panel repair, door mechanisms, window regulators, interior trim, body sealant, and structural components.
Routine Maintenance:
Oil changes, filter replacements, fluid checks and top-offs, spark plug replacement (for gasoline variants, but relevant context for a comprehensive manual), air filter replacement, tire rotation and pressure checks.
Engine Overhaul:
Detailed instructions for engine disassembly, component inspection, repair, and reassembly, including piston ring replacement, valve adjustments, and cylinder head gasket replacement.
Transmission Repair:
Step-by-step guides for rebuilding or repairing both manual and automatic transmissions.
Brake System Repair:
Brake pad and rotor replacement, caliper rebuilding, brake fluid flush and bleeding procedures.
Electrical Troubleshooting:
Diagnostic procedures for electrical faults, using wiring diagrams, and testing electrical components.
Diagnostics:
Troubleshooting guides for common problems, symptom-based diagnostics, and specific component testing procedures.
Repair Scope:
Covers everything from basic maintenance to complete engine and transmission rebuilds, including in-depth electrical diagnostics and bodywork.
Illustrations Quality:
Hundreds of detailed photos, drawings, and exploded views to guide repairs. Includes enlarged inset views for intricate components.
Target Audience:
Suitable for both DIY enthusiasts and experienced professional mechanics due to its comprehensive detail.
Wheelbase:
Approximately 2810 mm (110.6 inches) for sedan, longer for wagon.
Length:
Varies by body style, sedan around 4750 mm (187 in).
Curb Weight:
Approximately 1450-1550 kg (3200-3400 lbs) depending on configuration.
Gross Vehicle Weight Rating:
Typically around 2000-2100 kg (4400-4600 lbs).
Original Infotainment:
Basic AM/FM radio, potentially with cassette player. Analog instrumentation for all functions.
Driver Assistance Features:
Limited to mechanical systems like power steering. No electronic driver assistance systems (e.g., ABS, traction control) were standard or widely available on early models.
Connectivity Features:
None by modern standards. Features focused on mechanical reliability and comfort.
Oil Change Interval:
Typically every 5,000 to 10,000 km (3,000 to 6,000 miles) or annually, depending on operating conditions and oil quality. Manual will specify.
Fuel Filter Replacement:
Recommended every 20,000 to 30,000 km (12,000 to 18,000 miles). Manual will have precise interval.
Engine Oil:
API CD or ACEA B3/B4 rated diesel engine oil, viscosity typically 15W-40 or 10W-40. Manual will specify exact MB-approval.
Coolant:
Ethylene glycol-based coolant, typically a 50/50 mix with distilled water. MB specification 325.0.
Transmission Fluid Auto:
Dexron III/Mercon compatible ATF. Manual will specify exact MB fluid type.
Diesel Engine Longevity:
Known for extreme longevity; often reach 500,000 miles or more with proper maintenance. Common issues include injector pump seals and glow plug failures.
Body Rust:
Can be susceptible to rust in certain areas (e.g., fender wells, rocker panels, battery tray) depending on climate and care. Early detection and treatment are key.
Suspension Wear:
Ball joints, tie rod ends, and subframe bushings can wear over time, leading to steering looseness and noise.
Mercedes Benz Legacy:
Mercedes-Benz has a long history of producing robust and reliable diesel engines, setting industry standards for durability and efficiency.
W123 Introduction:
The W123 chassis was introduced in 1976 as the successor to the W114/W115 series, offering improved aerodynamics, comfort, and safety features.
Facelifts Updates:
The W123 received several updates throughout its production run, including minor styling tweaks and powertrain enhancements, particularly around 1982 (often referred to as the 'facelift').
Production Period:
1976-1985
Production Volume:
Over 2.7 million units were produced across all body styles, making it a highly successful model for Mercedes-Benz.
