Segment:
Mid-size executive sedan and wagon, known for durability, comfort, and reliability, particularly the diesel variants.
Contemporaries:
Competed with models from BMW (E21, E30), Audi (80/90), Volvo (240 Series), and other European luxury and durable sedans of the era.
Durability:
Renowned for its robust engineering and longevity, especially the diesel engines which often exceeded 500,000 miles.
Comfort:
Offered a comfortable ride and well-appointed interior, setting a standard for its class.
Safety:
Designed with a focus on safety, featuring crumple zones and a robust body structure.
Vehicle Coverage:
1976-1985 Mercedes-Benz W123 Series (200D, 240D, 240TD, 300D, 300TD)
Estimated Page Count:
Approximately 1000+ pages (comprehensive workshop manual)
Type:
Complete Workshop Service and Repair Manual
Format:
Digital (likely PDF, potentially printable)
Engine:
Diesel engine overhaul, fuel injection system (Bosch VE rotary pump), cooling system, lubrication system, exhaust system, engine management (basic).
Transmission:
Manual transmission (4 & 5 speed) repair, automatic transmission (3 & 4 speed) overhaul and service, clutch system, drive shafts, differential.
Brakes:
Hydraulic brake system, front disc brakes (calipers, rotors), rear drum brakes, parking brake, brake fluid specifications, bleeding procedures.
Suspension Steering:
Front independent suspension (double wishbone), rear semi-independent suspension (swing axle/semi-trailing arm), shock absorbers, coil springs, steering box, power steering system.
Electrical:
12V electrical system, battery, alternator, starter motor, ignition system (glow plug system for diesel), lighting system, wiring diagrams, fuses, relays, dashboard instruments.
Body Chassis:
Body construction, chassis components, doors, windows, sunroof, interior trim, seats, bumpers, corrosion protection.
Maintenance:
Scheduled maintenance, oil changes, filter replacements (oil, fuel, air), fluid level checks and top-ups, tune-up procedures.
Repair Rebuild:
Engine component replacement, transmission rebuild, brake system repair, suspension component overhaul, starter/alternator replacement.
Diagnostics Troubleshooting:
Systematic diagnostic flowcharts, common fault identification and correction for engine, transmission, electrical, and braking systems.
Specifications Data:
Torque specifications for all fasteners, engine clearances, timing specifications, fluid capacities, part numbers for common wear items.
Depth:
Comprehensive, covering from basic maintenance to complete engine and transmission rebuilds, including detailed diagnostic procedures.
Engine Type Diesel:
Inline-four and inline-five cylinder naturally aspirated diesel engines.
Engine Displacement 200D:
2.0 Liters (1988 cc)
Engine Displacement 240D:
2.4 Liters (2399 cc)
Engine Displacement 300D:
3.0 Liters (2998 cc)
Engine Displacement 300Td:
3.0 Liters (2998 cc) - Turbocharged Diesel (for some markets/years, often associated with the OM617.95x engine).
Horsepower 200D:
Approx. 55-60 hp
Horsepower 240D:
Approx. 65-70 hp
Horsepower 300D:
Approx. 77-80 hp
Torque 300D:
Approx. 130-140 lb-ft (176-190 Nm)
Injection System:
Bosch inline mechanical fuel injection pump (VE rotary for later models).
Glow Plug System:
Pre-glow system for cold starts, with manual or automatic timer controls.
Standard Transmission:
4-speed manual transmission (common on base models).
Optional Transmission:
5-speed manual transmission, 3-speed automatic (722.1 series), 4-speed automatic (722.3 series).
Automatic Transmission Features:
Hydraulic torque converter, offering smooth power delivery and increasing fuel efficiency on the highway.
Crash Test Information:
While formal crash test ratings from modern bodies are not directly applicable, the W123 was engineered with advanced safety features for its era, including significant structural integrity and crumple zones.
Braking System:
Four-wheel disc brakes (front) and rear disc or drum brakes depending on model and market, with power assistance and dual-circuit hydraulics.
Body Structure:
Reinforced passenger cell, crumple zones at front and rear, safety steering column.
Interior Safety:
Padded dashboard, energy-absorbing interior surfaces, safety belts (standard or optional depending on year/market).
Oil Change Interval Diesel:
Typically every 7,500-10,000 miles (12,000-16,000 km) or annually, depending on driving conditions and oil used.
Fuel Filter Replacement:
Recommended every 15,000-20,000 miles (24,000-32,000 km).
Air Filter Replacement:
Recommended annually or every 15,000 miles (24,000 km).
Engine Oil Spec:
API CD or higher for diesel engines (e.g., SAE 15W-40, 10W-40 depending on climate and manufacturer recommendation).
Coolant Spec:
Ethylene glycol based antifreeze with corrosion inhibitors (typically a 50/50 mix with distilled water).
Brake Fluid Spec:
DOT 3 or DOT 4 hydraulic brake fluid.
Automatic Transmission Fluid:
Mercedes-Benz Specification 236.1 or equivalent (e.g., Dexron II compatible).
Diesel Engine Reliability:
Generally excellent, but injector pump seals, timing chain wear, and valve guide wear can occur with high mileage.
Body Corrosion:
Susceptible to rust in common areas like wheel arches, rocker panels, and around window seals, especially in humid climates.
Electrical System:
Wiring harness degradation over time, particularly brittle insulation; vacuum lines for central locking and climate control can also leak.
Suspension Components:
Worn control arm bushings, ball joints, and idler arms can lead to steering wander.
Mercedes Benz Philosophy:
Reputation for building durable, reliable, and technologically advanced vehicles, particularly in the luxury and commercial sectors.
W123 Introduction:
Introduced in 1976 as the successor to the W114/W115 (Stroke Eight) series.
Design Influences:
Styled by Bruno Sacco, known for its clean lines, aerodynamic efficiency, and enduring design.
Production Years:
1976-1986 (Sedan and Coupe), 1977-1985 (Wagon - T-model)
Production Volume:
Over 2.7 million units produced across all body styles, making it one of Mercedes-Benz's most successful models.
