Segment:
Mid-size Luxury Coupe / Sedan
Era:
Iconic 1980s Mercedes-Benz
Competitors:
BMW 3 Series, Audi Coupe, Volvo 240 Series
Usp:
Robust engineering, diesel efficiency, legendary build quality
Vehicle Philosophy:
Durability, performance, refined comfort, understated luxury
Manual Benefit:
Empowers owners and technicians with the knowledge to maintain and repair this classic vehicle accurately.
Engine Mechanical:
Complete overhaul, component testing, timing, fuel injection system
Engine Electrical:
Ignition, starting system, charging system, sensors
Fuel System:
Diesel injection pump, injectors, fuel lines, filters, glow plug system
Transmission:
Automatic transmission service, fluid changes, general troubleshooting
Drivetrain:
Driveshaft, differentials, axle shafts
Suspension:
Front and rear suspension components, shock absorbers, springs, control arms
Steering:
Power steering system, steering linkage, steering column
Brakes:
Hydraulic system, disc and drum brakes, parking brake, ABS (if equipped)
Electrical System:
Wiring diagrams, lighting, instrumentation, accessories, power windows, central locking
HVAC:
Heating, ventilation, air conditioning system service
Body And Chassis:
Body panels, doors, windows, interior trim, chassis lubrication
Maintenance:
Scheduled maintenance, fluid checks, filter replacements, lubrication
Troubleshooting:
Diagnostic procedures, symptom-based troubleshooting, fault codes
Repair:
Step-by-step repair instructions for all major components and systems
Diagnostics:
Detailed diagnostic trees, component testing procedures, electrical troubleshooting
Depth:
Comprehensive, from basic maintenance to complete engine and transmission rebuilds
Detail Level:
Includes torque specifications, alignment data, and diagnostic flowcharts
Type:
Inline 5-Cylinder Diesel with Turbocharger
Displacement:
2998 cc (3.0 Liters)
Bore X Stroke:
87.0 mm x 92.3 mm
Compression Ratio:
21.0:1
Horsepower:
90 hp @ 4350 rpm
Torque:
125 lb-ft @ 2400 rpm
Injection System:
Bosch Inline Injection Pump (M-type)
Glow Plugs:
Yes, pre-heating system
Oil Type Specification:
API CD or ACEA B2, SAE 15W-40 (or 10W-30 in very cold climates)
Coolant Type:
Ethylene Glycol based, 50/50 mix with distilled water
Type:
4-Speed Automatic (4G-TRONIC)
Type:
5-Speed Manual (Less Common in US Market)
Automatic Modes:
Economy (E) and Sport (S) modes
Automatic Transmission Fluid:
MB 236.1 Specification (e.g., ATF Dexron III is often a suitable substitute, but check manual for exact spec)
NHTSA Front Impact:
Not rated (Vehicle predates modern comprehensive testing)
ABS:
Optional (available on higher trims or later models)
Airbags:
Driver's airbag optional, not standard
Seatbelts:
3-point front seatbelts, lap belts in rear
Crumple Zones:
Designed with energy-absorbing zones
Oil And Filter Change:
Every 5,000 - 7,500 miles or annually (refer to manual for exact recommendation)
Fuel Filter Replacement:
Every 15,000 - 20,000 miles
Air Filter Replacement:
Every 15,000 - 20,000 miles
Valve Adjustment:
Every 30,000 - 45,000 miles
Engine Oil Capacity:
7.5 Liters (7.9 Quarts)
Coolant Capacity:
10.5 Liters (11.1 Quarts)
Brake Fluid:
DOT 3 or DOT 4 (Check manual for precise specification)
Common Problems:
Valve cover gasket leaks, vacuum hose degradation, idle control issues, potential for injector pump issues if not properly maintained.
Diesel Specific:
Glow plug system reliability, fuel system maintenance is critical for longevity.
Idle Speed Adjustment:
Requires understanding of injection pump linkage and vacuum controls.
Mercedes Benz Legacy:
Pioneering automotive manufacturer with a focus on engineering excellence and longevity.
W123 Generation:
Part of the highly regarded W123 series (1976-1985), known for its exceptional build quality and durability.
300Cd Variant:
Coupe version of the popular 300D sedan, offering a sportier profile.
Production Years:
1977-1985 (for W123 Coupes, 1981-1985 for 300CD in North America)
Manufacturing Location:
West Germany
Legacy Perception:
Consistently ranked among the most reliable and durable Mercedes-Benz models ever produced.
Consumer Reports Reputation:
Highly praised for reliability and longevity in period reviews.
Manual Validation:
Represents genuine factory service information, crucial for correct repairs.
