Positioning:
The Mercedes-Benz 300TD (W123 diesel variants) was positioned as a durable, luxurious, and fuel-efficient mid-size executive car, renowned for its robust engineering and longevity.
Competitors:
Competed with other European luxury sedans and estates from brands like BMW, Audi, Volvo, and Jaguar during its production run. Its diesel engine offered a distinct advantage in fuel economy.
Unique Selling Points:
Legendary Mercedes-Benz build quality, the reliable OM617 five-cylinder diesel engine, exceptional ride comfort, advanced safety features for its era, and impressive durability.
Applicable Years:
1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985
Body Styles:
Sedan, Coupe, Wagon (Estate/T-Model), potentially Limousine variants
Estimated Page Count:
1000+
Type:
Service and Repair Manual
Powertrain:
Engine (OM617 diesel), Fuel System, Exhaust System, Cooling System, Lubrication System, Starting System, Charging System
Drivetrain:
Manual Transmission, Automatic Transmission, Driveshafts, Differentials, Axles
Chassis:
Suspension (front and rear), Steering System, Brake System (hydraulic, front disc, rear drum/disc), Wheel Bearings
Electrical:
Wiring Diagrams, Lighting System, Ignition System, Instruments and Gauges, Power Accessories, Fuses and Relays, Battery
Body And Interior:
Body Panels, Doors, Windows, Seats, Trim, HVAC System (Heating, Ventilation, Air Conditioning), Convertible Tops (if applicable)
Maintenance:
Oil Changes, Filter Replacements, Fluid Checks and Replacements, Belt Inspections and Adjustments, Spark Plug Replacement (for gasoline variants), Glow Plug Checks
Troubleshooting:
Diagnostic Procedures for common issues, symptom-based troubleshooting guides
Repair:
Component Removal and Installation, Engine Overhaul, Transmission Rebuilds, Brake System Overhaul, Suspension Component Replacement, Electrical Component Diagnosis and Repair
Depth:
Comprehensive, covering routine maintenance, diagnostics, and in-depth mechanical and electrical repairs. Suitable for professional mechanics and experienced DIY enthusiasts.
Engine Type:
Inline 5-cylinder, naturally aspirated Diesel
Engine Code:
OM617.912 (typically)
Displacement:
3.0 Liters (2998 cc)
Horsepower:
Approx. 77-83 hp (depending on specific market/tuning)
Torque:
Approx. 130-137 lb-ft (176-186 Nm) at around 2400 RPM
Injection Type:
Bosch Inline Fuel Injection Pump
Coolant Type:
Mercedes-Benz Specification Coolant (e.g., MB 325.0 or equivalent blue/green glycol-based antifreeze)
Oil Type:
API CD or CE rated Diesel Engine Oil, SAE 15W-40 or 10W-30 depending on climate
Oil Capacity:
Approx. 7.5 Liters (with filter)
Glow Plugs:
Pre-combustion chamber type glow plugs, crucial for cold starts
Type:
4-speed Manual Transmission (often)
Type:
4-speed Automatic Transmission (e.g., 4G-Tronic)
Automatic Transmission Fluid:
Dexron II or equivalent ATF
Crash Safety:
Designed to meet rigorous safety standards of its era; featured crumple zones and reinforced passenger cell. Specific NHTSA/Euro NCAP ratings may not be directly available for this vintage.
Braking:
Power-assisted front disc brakes, rear drum brakes (later models may have rear discs). Anti-lock Braking System (ABS) became available on some later W123 models, though less common on the 300TD.
Restraints:
Seat belts (lap belts in front, potentially three-point in rear depending on year/market), padded dashboard, collapsible steering column.
Oil And Filter Change:
Every 5,000 - 10,000 km or 6-12 months (refer to manual for precise interval based on driving conditions)
Air Filter Replacement:
Every 20,000 - 30,000 km or as needed based on environment
Fuel Filter Replacement:
Every 20,000 - 40,000 km or as needed
Coolant Flush:
Every 2-3 years or as recommended
Brake Fluid:
DOT 3 or DOT 4 Brake Fluid
Power Steering Fluid:
ATF Dexron II or equivalent
Common Problems:
Rust (especially wheel arches, rocker panels, jacking points), Injector pump seals (OM617), Glow plug issues, Vacuum leaks, Heater control valve failures, Potential for oil cooler leaks.
Diesel Specific Issues:
Injector pump timing, fuel system bleeding after filter changes, cold start reliability if glow plug system is not maintained.
Oil Filter Example:
Mann-Filter MH 120 / MB Part No. 000 180 2309 (example, verify for specific model)
Air Filter Example:
Mann-Filter C 22 125 / MB Part No. 115 094 05 04 (example, verify for specific model)
Legacy:
Mercedes-Benz has a long-standing reputation for engineering excellence, safety, and durability, established long before the W123 generation.
W123 Generation:
The W123 chassis, introduced in 1976, succeeded the W114/W115 'Stroke Eight' series. The 300TD specifically represents the diesel wagon variant, known for its practicality and efficiency.
Production Years:
W123 Series: 1976-1986 (global production, specific 300TD production aligns with manual coverage)
Manufacturing Locations:
Germany, Austria, South Africa, Argentina, others
