Segment:
Luxury Diesel Sedan/Coupe (W123 Chassis)
Target Audience:
Owners and independent mechanics seeking in-depth repair and maintenance knowledge
Competitors:
BMW 5 Series Diesel, Audi Diesel models of the era
Vehicle Appeal:
Durability, fuel economy, robust diesel engine, build quality
Manual Value:
Empowers DIY owners to maintain and repair their classic Mercedes-Benz effectively
Engine:
3.0L Inline 5-Cylinder Turbo Diesel (OM617.952)
Fuel System:
Bosch VE Injection Pump, Fuel Lines, Filters, Glow Plug System
Cooling System:
Radiator, Water Pump, Thermostat, Hoses, Fan Clutch
Exhaust System:
Manifold, Downpipe, Mufflers, Catalytic Converter (if equipped)
Transmission:
4-Speed Automatic (722.3)
Drivetrain:
Rear Wheel Drive, Driveshaft, Differential, Axles
Suspension:
Front Independent, Rear Independent (Semi-Trailing Arm), Springs, Dampers, Bushings
Steering:
Power-Assisted Recirculating Ball System
Brakes:
Front Disc, Rear Disc, Hydraulic System, Parking Brake
Electrical System:
12V System, Battery, Alternator, Starter, Wiring Diagrams, Lighting
Climate Control:
HVAC System, Heater Core, A/C Components (if equipped)
Body:
Body Panels, Doors, Windows, Locks, Exterior Trim
Interior:
Seats, Dashboard, Upholstery, Trim Panels
Diagnostic Troubleshooting:
Systematic Fault Finding Guides
Maintenance:
Oil Changes, Filter Replacements, Fluid Checks, Belt Adjustments, Spark Plug Replacement (Diesel equivalent – Glow Plugs)
Repair:
Engine Overhaul, Transmission Rebuild, Brake System Repair, Suspension Component Replacement, Electrical Component Diagnosis and Replacement
Adjustment:
Valve Clearances, Injection Pump Timing, Steering Linkage
Disassembly Assembly:
Component-level breakdown and reassembly instructions
Depth:
Comprehensive (from basic maintenance to complete engine and transmission rebuilds)
Diagnostic Focus:
Detailed symptom-based diagnostics and specific troubleshooting charts
Torque Specifications:
All critical fastener torque values included
Wiring Diagrams:
Complete and detailed electrical schematics
Engine Type:
Inline 5-Cylinder, Overhead Camshaft (OHC), Naturally Aspirated Diesel
Displacement:
3.0 Liters (2998 cc)
Bore X Stroke:
87.0 mm x 92.4 mm
Compression Ratio:
21.0:1
Horsepower:
85 hp @ 4200 rpm (approx.)
Torque:
135 lb-ft @ 2400 rpm (approx.)
Injection System:
Bosch Inline Fuel Injection Pump (VE type)
System:
Pre-combustion chamber glow plug system
Capacity:
7.5 Liters (8.0 US Quarts)
Recommended Viscosity:
SAE 15W-40 (or 10W-30/10W-40 depending on climate)
Specification:
API CD or ACEA B2
NHTSA Rating:
Not explicitly rated by NHTSA under modern standards, but known for robust construction.
Airbags:
Driver airbag (optional/standard depending on market and production date)
Seatbelts:
Front and rear seat belts
Construction:
Reinforced safety cage, crumple zones
ABS:
Anti-lock Braking System (Optional on some models)
Oil Change:
Every 5,000 miles or 6 months
Air Filter Replacement:
Every 15,000 miles or 12 months
Fuel Filter Replacement:
Every 10,000 miles or 12 months
Glow Plug Check:
As needed, per manual troubleshooting
Coolant:
50/50 mix of Mercedes-Benz approved coolant and distilled water
Common Problems:
Vacuum leak issues (door locks, climate control), injector pump seals, injector line leaks, rust (especially around wheel wells and rocker panels), potential valve seat wear on high-mileage engines.
Common Problems Continued:
Transmission cooling line leaks, suspension bushings wear, front axle kingpins wear.
Mercedes Benz Legacy:
Pioneers in automotive engineering, known for diesel technology and luxury vehicles.
W123 Generation:
Part of the highly regarded W123 series (1976-1985), known for exceptional durability and build quality.
Cd Designation:
Represents the 'Coupe Diesel' variant, though also available as a sedan.
Production Years:
W123 series: 1976-1985. Specific 300CD production: 1978-1985.
Manufacturing Location:
Germany (primarily)
