Vehicle Segment:
Mid-size luxury sedan/coupe/wagon, known for durability and comfort.
Target Audience For Manual:
Mercedes-Benz W123 owners, DIY mechanics, professional automotive technicians, classic car enthusiasts.
Competitors Vehicle:
BMW E21/E30 3 Series, Audi 5000, Volvo 240, Cadillac Seville.
Manual Value Proposition:
Provides professional-level repair information to maintain and restore a robust and iconic Mercedes-Benz model.
Manual Highlights:
Comprehensive coverage, detailed diagrams, step-by-step instructions, professional mechanic-grade content, lifetime access.
Vehicle Highlights:
Legendary Mercedes-Benz build quality, reliability, durability, comfortable ride, efficient diesel engine.
Engine Mechanical:
Complete overhaul, disassembly, assembly, timing, valve adjustment, fuel injection system, cooling system, lubrication system.
Engine Electrical:
Ignition system (if applicable for diesel glow plugs), starting system, charging system, sensors, wiring diagrams.
Fuel System:
Diesel injection pump, injectors, fuel lines, fuel filters, pre-heating system.
Transmission:
Manual and automatic transmission overhaul, clutch replacement, shift linkage adjustments, fluid specifications.
Drivetrain:
Driveshafts, axles, differential, universal joints, lubrication.
Suspension:
Front and rear suspension components, shock absorbers, springs, bushings, wheel alignment procedures.
Steering:
Power steering system, steering box, tie rods, steering column, adjustments.
Brakes:
Hydraulic system, brake fluid, master cylinder, wheel cylinders, brake calipers, brake pads, brake discs, parking brake, bleeding procedures.
Electrical System:
Battery, starter, alternator, lighting systems, wipers, horn, instrumentation, fuses, relays, wiring diagrams for all circuits.
Body And Chassis:
Body panel repair, door mechanisms, window regulators, sunroof, interior trim, underbody protection.
Heating And Air Conditioning:
HVAC system components, refrigerant, blower motor, climate control operation (if equipped).
Maintenance:
Scheduled maintenance, oil changes, filter replacements, fluid checks and top-offs, lubrication points, belt adjustments.
Troubleshooting:
Diagnostic procedures for common and uncommon issues, symptom-based troubleshooting guides.
Repair:
Step-by-step instructions for all major and minor repairs, including complete component rebuilds.
Installation:
Procedures for replacing or installing new or reconditioned parts.
Diagnostics:
Detailed diagnostic charts and procedures, often including fault codes if applicable.
Depth Of Coverage:
Professional-grade, comprehensive, covering all aspects from routine maintenance to complete engine and transmission rebuilds.
Diagrams And Illustrations:
Hundreds of detailed photos, exploded diagrams, and schematics to illustrate procedures.
Torques And Specifications:
Precise torque values for all fasteners, critical clearances, and adjustment specifications.
Engine Configuration:
Inline-5 Cylinder
Displacement:
3.0 Liters (2998 cc)
Bore X Stroke:
87.0 mm x 100.0 mm (typical for OM617)
Compression Ratio:
21.0:1 (typical for OM617)
Horsepower Est:
77-88 hp @ 4000-4200 rpm (varies slightly by specific OM617 variant)
Torque Est:
130-140 lb-ft @ 2400 rpm (varies slightly by specific OM617 variant)
Injection System:
Bosch Mechanical Fuel Injection (Inline Injection Pump)
Glow Plug System:
Yes, for cold starting assistance.
Engine Control:
Primarily mechanical with some electrical actuation for glow plugs and shutdown.
Safety Certification Era:
Pre-modern era safety standards; focused on passive safety and build integrity.
Braking System:
Four-wheel disc brakes (standard on many later models and optional earlier), ABS not standard on early models, may be present on late W123s.
Steering System:
Recirculating ball steering with power assist.
Body Construction:
Reinforced safety cage, crumple zones, impact-absorbing steering column, door impact bars.
Airbags:
Not available for this model range.
Seat Belts:
Standard front seat belts, optional rear seat belts depending on market and year.
Oil Change Interval Est:
Typically every 5,000 - 7,500 miles (8,000 - 12,000 km) or 6-12 months.
Air Filter Replacement Est:
Every 15,000 - 30,000 miles (24,000 - 48,000 km) or as needed based on conditions.
Fuel Filter Replacement Est:
Every 10,000 - 15,000 miles (16,000 - 24,000 km) for diesel.
Engine Oil Spec:
API CD or ACEA B2/E2 rated diesel engine oil, viscosity typically 15W-40 or 10W-40 depending on climate. Consult manual for exact MB specification.
Coolant Spec:
Ethylene glycol-based antifreeze, typically a 50/50 mix with distilled water. Consult manual for MB approved coolant.
Brake Fluid Spec:
DOT 3 or DOT 4 brake fluid. Must be replaced periodically due to hygroscopic nature.
Common Issues Diesel:
Glow plug failure, injection pump seal leaks, valve cover gasket leaks, vacuum leak issues (for central locking/door locks), overheating (due to cooling system age), potential rust in common areas (wheel arches, sills).
Common Issues General:
Worn suspension bushings, aged rubber hoses and seals, potential electrical connector corrosion, HVAC blower motor failure.
Preventative Maintenance Importance:
Crucial for longevity due to the robust but complex nature of the vehicle. The manual is essential for proper DIY maintenance.
Mercedes Benz Philosophy:
Renowned for engineering excellence, durability, luxury, and pioneering automotive technologies.
W123 Legacy:
The W123 is considered one of the most robust and durable Mercedes-Benz models ever produced, often referred to as the 'tank'.
Body Styles:
Sedan (4-door), Coupe (2-door), Wagon (T-model), Long Wheelbase Limousine.
Production Years Global:
1976-1985
Production Locations:
Germany (Sindelfingen), Austria (Graz), South Africa, others.
