Target Audience:
Mercedes-Benz 300 CD owners, independent repair shops, and automotive enthusiasts seeking detailed technical information.
Value Proposition:
Provides critical, often unavailable, factory-specific knowledge for maintenance, repair, and restoration of the W123 300 CD.
Alternatives:
Third-party repair manuals (Haynes, Chilton) often lack the depth and accuracy of factory documentation.
Authenticity:
Directly sourced from Mercedes-Benz factory documentation.
Diagnostic Capability:
Enables in-depth troubleshooting and accurate repair of complex systems.
Engine:
OM617.952 Diesel Engine (3.0L Inline 5-Cylinder Turbocharged)
Fuel System:
Bosch VE Injection Pump, Glow Plug System, Fuel Lines, Filters
Cooling System:
Radiator, Water Pump, Thermostat, Hoses, Fan Clutch
Exhaust System:
Manifold, Downpipe, Muffler, Catalytic Converter (where applicable), Emission Controls
Transmission:
4-Speed Automatic (722.118)
Drivetrain:
Rear Wheel Drive, Driveshaft, Differential, Axles
Suspension:
Front Independent (Double Wishbone), Rear Independent (Semi-Trailing Arm), Springs, Shock Absorbers, Anti-Roll Bars
Steering:
Recirculating Ball Steering Gear, Power Steering System, Steering Column
Brakes:
Front Discs, Rear Discs, Hydraulic System, Parking Brake
Electrical System:
Battery, Charging System (Alternator), Starting System (Starter), Ignition System (Glow Plugs), Lighting, Fuses, Relays, Wiring Diagrams
Body And Chassis:
Body Construction, Doors, Hood, Trunk, Windows, Seals, Interior Trim, Sound Deadening
Climate Control:
HVAC System, Heater Core, Blower Motor, Air Conditioning (where equipped)
Maintenance:
Oil Changes, Filter Replacements, Fluid Checks and Top-Offs, Belt Adjustments, Air Cleaner Service
Troubleshooting:
Diagnostic Charts, Symptom-Based Problem Solving, Fault Code Identification (where applicable)
Repair:
Engine Overhaul, Transmission Rebuild, Brake System Repairs, Suspension Component Replacement, Electrical Component Diagnosis and Replacement
Adjustment:
Valve Lash Adjustment, Injection Pump Timing, Parking Brake Adjustment
Inspection:
Pre-delivery Inspection (PDI), Regular Inspection Checklists
Installation:
Component Installation and Removal Procedures
Depth:
Factory-level detail including torque specifications, clearance measurements, component removal/installation sequences, and diagnostic procedures.
Engine Type:
Turbocharged Diesel, Inline 5-Cylinder
Displacement:
3.0 Liters (2998 cc)
Bore X Stroke:
90.9 mm x 107.0 mm
Compression Ratio:
21.5:1
Horsepower Net:
83 hp @ 4000 rpm (approx.)
Torque Net:
131 lb-ft @ 2400 rpm (approx.)
Injection System:
Bosch Inline Fuel Injection Pump (VE type), Mechanical Injection
Fuel Type:
Diesel Fuel (ASTM D975 Grade 1-D or 2-D)
Glow Plug System:
Direct electric pre-heating of combustion chambers for cold starts.
Engine Oil Capacity:
7.5 Liters (8 US Quarts) with filter change
Engine Oil Specification:
API CD or higher, SAE 15W-40 or 10W-30 (depending on climate)
Seat Belts:
Front 3-point automatic seat belts, rear lap belts.
Body Construction:
Reinforced safety cage, crumple zones, energy-absorbing steering column.
Headrests:
Front and rear headrests (design varies by year).
Braking System:
Four-wheel disc brakes with power assistance.
Steering:
Power-assisted recirculating ball steering for improved control.
Crash Test Data:
As a vintage vehicle, formal crash test data from modern agencies (NHTSA, IIHS) may not be directly comparable or available for all model years. The W123 chassis was engineered with significant safety advancements for its era.
Oil Change Interval:
Typically every 5,000-7,500 miles (8,000-12,000 km) or 6-12 months, depending on driving conditions and oil used. Consult manual for precise intervals.
Air Filter Replacement:
Every 15,000-20,000 miles (24,000-32,000 km) or as needed based on dust conditions.
Fuel Filter Replacement:
Every 15,000-25,000 miles (24,000-40,000 km). Crucial for diesel engine health.
Transmission Fluid Change:
Typically every 25,000-30,000 miles (40,000-48,000 km).
Valve Adjustment:
Recommended every 30,000-50,000 miles (48,000-80,000 km) or as per manual's guidance for optimal engine performance and longevity.
Engine Mounts:
Wear and tear leading to vibration transmission into the cabin.
Vacuum System:
Leaks in the vacuum lines can affect central locking, climate control flaps, and door locks.
Rust Progression:
Common on older Mercedes-Benz models, particularly around wheel arches, sills, and door bottoms. Thorough inspection is recommended.
Burette Type Thermostatic Time Switch:
Failure can impact cold start performance.
Injector Nozzles:
Can become clogged or worn over time, affecting fuel atomization and engine performance.
Coolant Specification:
Ethylene Glycol based coolant, typically MB-approved 325.0 (blue) or 326.0 (green) with appropriate anti-corrosion additives. A 50/50 mix with distilled water is standard.
Brake Fluid Specification:
DOT 3 or DOT 4 brake fluid (check manual for exact specification). Must be changed periodically to prevent moisture absorption.
Power Steering Fluid:
MB 236.3 hydraulic fluid or Dexron II (check manual for exact MB specification).
Manufacturer Origin:
Germany
Reputation:
Mercedes-Benz is renowned for engineering excellence, build quality, and durability.
W123 Introduction:
The W123 chassis was introduced in 1976 as the successor to the W114/W115. It was available in sedan, wagon, coupe, and long-wheelbase versions.
300 Cd Positioning:
The 300 CD coupe (C123) offered a more stylish and performance-oriented variant of the robust W123 platform, targeting buyers who desired Mercedes-Benz luxury with a diesel powertrain.
Production Period:
1976-1985
Manufacturing Locations:
Various Mercedes-Benz plants globally (primarily Germany).
