Target Audience:
Mechanical technicians, experienced DIY enthusiasts
Value Proposition:
Enables professional-level repairs and maintenance, potentially saving significant costs compared to dealership service.
Safety Emphasis:
Highlights safety precautions and use of proper tools like torque wrenches.
Special Tools:
Identifies and illustrates recommended or required special tools by Mercedes-Benz part numbers.
Information Reliability:
Provides the most reliable information, aiming for accuracy.
Dealer Level Information:
Contains specifications and procedures comparable to authorized dealer service departments.
Warning Symbols:
Utilizes WARNING, CAUTION, and NOTE symbols to highlight critical information.
Engine:
Complete overhaul, diagnostics, repair, tune-ups
Fuel System:
Carburetor (Solex or Zenith) or Fuel Injection (Bosch K-Jetronic) system repair and adjustment
Ignition System:
Distributor, coil, spark plugs, timing adjustment
Lubrication System:
Oil pump, oil filter, oil passages, oil pressure checks
Exhaust System:
Muffler, catalytic converter (if applicable), exhaust manifold repair
Electrical System:
Wiring diagrams, starter, alternator, battery, lighting, fuses, relays, diagnostic procedures
Cooling System:
Radiator, water pump, thermostat, hoses, coolant specifications
Transmission:
Manual and automatic transmission overhaul, repair, fluid specifications, and removal/installation
Drivetrain:
Driveshaft, differential, axles, universal joints
Suspension:
Front and rear suspension components, shock absorbers, springs, bushings, alignment specifications
Steering:
Steering gearbox, power steering system, tie rods, steering wheel removal/installation
Brakes:
Front and rear disc brake systems, hydraulic lines, master cylinder, calipers, brake fluid specifications
Body:
Body panel repair, doors, windows, locks, interior trim, weatherstripping
Climate Control:
Heater core, ventilation system, air conditioning system (if equipped)
Routine Maintenance:
Oil changes, filter replacements, spark plug service, fluid checks
Diagnostics:
Troubleshooting guides for common and uncommon issues
Repair:
Detailed step-by-step repair instructions for all major and minor components
Overhaul:
Comprehensive instructions for rebuilding major assemblies like the engine and transmission
Installation:
Procedures for removing and installing components
Assembly:
Detailed instructions for assembling and disassembling components and systems
Depth:
Advanced diagnostics and repair, suitable for professional technicians
Special Emphasis:
Special aspects of product repair, proprietary component instructions
Engine Type:
Inline 6-cylinder, naturally aspirated
Engine Displacement:
2.8 Liters (2781 cc)
Engine Code:
M110.984 (for carbureted version, specific code may vary slightly by market/year)
Valvetrain:
Dual Overhead Camshaft (DOHC), 2 valves per cylinder
Horsepower Approx:
140-150 PS (approx. 138-148 bhp) DIN (depending on year and market, may vary with fuel injection)
Torque Approx:
220-235 Nm (approx. 162-173 lb-ft) DIN (depending on year and market)
Fuel Delivery:
Initially carbureted (e.g., Solex 4A1 twin-choke) on earlier models, later transitioned to Bosch K-Jetronic mechanical fuel injection on some variants.
Fuel Type:
Unleaded gasoline (87 AKI / 91 RON recommended for most years)
Crash Testing:
While official ratings from modern agencies are not directly comparable, the W123 was renowned for its robust body structure and safety features for its era.
Brakes:
Four-wheel disc brakes (front ventilated) on most 280S models
Steering:
Recirculating ball steering with power assist
Body Construction:
Reinforced safety cage, crumple zones
Restraints:
Seatbelts (lap and shoulder belts standard)
Windshield:
Laminated safety glass
Oil Change:
Typically every 7,500-10,000 miles (12,000-16,000 km) or 12 months, whichever comes first (refer to manual for exact specs based on oil type used).
Air Filter Replacement:
Every 15,000-20,000 miles (24,000-32,000 km) or as needed based on driving conditions.
Spark Plug Replacement:
Typically every 20,000-30,000 miles (32,000-48,000 km) for standard plugs, or higher for platinum/iridium (consult manual for specific plug type).
Coolant Flush:
Every 2-3 years or 30,000-50,000 miles (48,000-80,000 km).
Engine Oil:
SAE 10W-40 or 20W-50, API SF/SG rating (or equivalent/better). Capacity approx. 7.5 liters.
Brake Fluid:
DOT 3 or DOT 4, typically 1 liter needed for a flush.
Power Steering Fluid:
Mercedes-Benz specified power steering fluid or Dexron II/III ATF.
Coolant:
50/50 mix of Mercedes-Benz approved antifreeze and distilled water.
Common Wear Items:
Ball joints, tie rod ends, control arm bushings, exhaust hangers, vacuum lines (prone to cracking), fuel injectors (K-Jetronic), fuel pump check valves.
Electrical Problems:
Corrosion in fuse box terminals, failing headlight switches, intermittent dashboard lights due to aged wiring.
Engine Performance:
Hesitation or rough running can be caused by worn fuel distributors, vacuum leaks, or incorrect ignition timing.
Manufacturer:
Mercedes-Benz AG
Generation:
First generation W123 series, succeeding the W114/W115 'Stroke Eight' models.
Introduction Year:
W123 series introduced in 1976.
Design Philosophy:
Known for exceptional build quality, durability, comfort, and safety, embodying Mercedes-Benz's reputation for engineering excellence.
Production Period:
1976-1985
Production Variants:
Sedan (W123), Coupe (C123), Estate/Wagon (S123), Long Wheelbase (V123)
