Market Segment:
Luxury Personal Coupe, renowned for its build quality and diesel efficiency in its era.
Key Competitors:
BMW 6 Series, Audi Coupe, Jaguar XJ-SC (though often priced higher)
Vehicle Strengths:
Durability of the OM617 diesel engine, refined ride quality, distinctive coupe styling, robust build quality.
Dealership Parity:
This is the same Repair Service manual used by local Mercedes-Benz dealerships.
Digital Delivery:
Instant download format offers immediate access without shipping delays or costs.
Engine System:
Diesel engine service, fuel injection system, timing, cooling system, lubrication, air intake, exhaust, V-belts, ignition (glow plugs)
Transmission System:
Manual and Automatic transmission fluid changes, level checks, and adjustments
Drivetrain System:
Front axle oil level, rear axle oil change and level check, drive shaft flexible coupling inspection
Brake System:
Brake fluid level, line inspection, pad and disc thickness, parking brake adjustment, fluid replacement, brake testing
Suspension Steering:
Suspension and body structure inspection, ball joint checking, tire pressure and condition, wheel bolt tightening, steering play, power steering fluid
Body Interior:
Water leakage and corrosion inspection, door hinge and lock lubrication, sunroof rails, soft top checks, windshield wiper and washer, hood lubrication, safety belts, seat backrest locks, lower noise encapsulation
Climate Control:
Cooling and heating system checks, AC refrigerant charge, dust filter replacement, active charcoal filter, recirculating air filter
Electrical Components:
Battery fluid level, warning and indicator lamps, headlamp and exterior lamp inspection
Maintenance Procedures:
Oil and filter changes, valve clearance adjustment, idle speed adjustment, fuel filter replacement, air filter cleaning/replacement, V-belt inspection, spark plug checks/replacement, coolant checks/replacement, brake fluid replacement
Troubleshooting Procedures:
Implied through detailed inspection and adjustment procedures for all covered systems
Repair Procedures:
Detailed instructions for component inspection, adjustment, and replacement across all systems
Depth Of Coverage:
Comprehensive factory-level detail, including adjustments, inspections, and replacements, suitable for dealership technicians and skilled DIY enthusiasts.
Engine Type:
Inline-5 Cylinder Turbocharged Diesel
Engine Displacement:
3.0 Liters (2998 cc)
Horsepower:
Approx. 125 hp @ 4350 rpm (varies slightly by market/year)
Torque:
Approx. 200 lb-ft @ 2400 rpm (varies slightly by market/year)
Fuel System Type:
Bosch Fuel Injection Pump, Mechanical Injection
Injection Timing Adjustment:
Covered in detail, crucial for performance and emissions.
Valve Clearance:
Adjustment and checking procedures included, typically requires shims.
Standard Transmission:
4-Speed Manual (less common)
Optional Transmission:
4-Speed Automatic (most common)
Automatic Transmission Fluid Type:
Typically Dexron-III or equivalent (specific MB spec to be verified in manual)
Manual Transmission Fluid Type:
Hypoid gear oil, API GL-4 or GL-5 (specific viscosity and spec in manual)
Era Safety Standards:
Reflects safety standards of the early 1980s; designed with a strong unibody structure.
Braking System:
Power-assisted disc front, drum rear (ABS not standard on most models of this era)
Airbags:
Not standard equipment for these model years.
Seat Belts:
Standard 3-point front, lap rear. Manual covers inspection and likely replacement/adjustment.
Original Infotainment:
Basic AM/FM radio, optional cassette player. Manual covers cleaning of tone head for cassette decks.
Advanced Features:
Limited by era; key features include power steering, cruise control (likely standard or common option), and possibly level control/self-leveling suspension (ADS, 4MATIC mentioned in manual, though 4MATIC was rare on coupes).
Connectivity Features:
N/A for modern standards; features like antenna mast inspection are covered.
Engine Oil Change:
Typically every 3,000-5,000 miles or 6 months, depending on driving conditions (manual will specify precise interval).
Transmission Fluid Change:
Automatic: every 30,000-50,000 miles. Manual: every 50,000-75,000 miles (refer to manual for exact recommendations).
Engine Oil Specification:
Diesel engine oil, typically SAE 15W-40 or 20W-40 (API CD or CE rated) - exact spec to be confirmed in manual.
Coolant Specification:
Ethylene glycol based antifreeze/coolant. Manual will provide Mercedes-specific P/N or equivalent.
Common Diesel Issues:
Glow plug reliability, injection pump seal leaks, vacuum shut-off mechanism issues, turbocharger health checks, potential for injector seal leaks. Manual provides diagnostic and repair procedures.
Body Corrosion:
Common for vehicles of this era, particularly around wheel wells, rocker panels, and jacking points. Manual covers inspection and likely minor repair guidance.
Comprehensive Schedules:
The manual will detail mileage/time-based maintenance schedules for all major systems.
Brand Legacy:
Mercedes-Benz has a long-standing reputation for engineering excellence, durability, and luxury, particularly in diesel technology.
W123 Platform:
The W123 chassis is legendary for its robust engineering and longevity. The 300 CD Turbo variant was a popular diesel coupe offering within this celebrated range.
Production Years For 300 Cd Turbo:
1978-1985 (CD Turbo designation specifically for North America)
W123 Platform Recognition:
The W123 platform is widely regarded as one of the most durable and reliable Mercedes-Benz models ever produced, often referred to as the 'Tank'.
Manual Certification:
Factory certified, implying accuracy and completeness as per Mercedes-Benz engineering standards.
