Segment:
Mid-size luxury sedan/sedan-diesel
Target Audience:
Owners seeking to maintain and repair their classic Mercedes-Benz diesel vehicles
Competitors:
BMW E28, Audi 5000, Volvo 240 Diesel
Vehicle Strength:
Exceptional build quality, durability, fuel efficiency, comfort
Manual Value Proposition:
Enables DIY maintenance and repair, preserving the longevity and value of a classic vehicle
Engine:
Detailed diagnosis, repair, overhaul, tuning for OM617 diesel engine
Fuel System:
Injection pump, injectors, fuel lines, filters, glow plug system
Transmission:
Manual and automatic transmission overhaul, maintenance, diagnostics
Drivetrain:
Clutch, driveshaft, differential, axles, wheel bearings
Suspension:
Front and rear suspension components, springs, shock absorbers, bushings, alignment
Steering:
Steering gear, power steering system, tie rods, linkages
Brakes:
Hydraulic system, brake calipers, master cylinder, wheel cylinders, parking brake, ABS (if applicable)
Electrical System:
Battery, charging system (alternator), starting system, ignition system, lighting, gauges, accessories
Cooling System:
Radiator, water pump, thermostat, hoses, coolant specifications
Exhaust System:
Manifold, catalytic converter (if applicable), mufflers, pipes
Body And Chassis:
Body panels, doors, windows, locks, upholstery, frame
HVAC:
Heating, ventilation, and air conditioning (HVAC) system
Maintenance:
Oil changes, filter replacements, fluid checks, belt adjustments, tune-ups
Troubleshooting:
Diagnostic flowcharts, symptom analysis, common problem resolution
Repair:
Step-by-step repair instructions for all major components and systems
Overhaul:
Complete engine and transmission rebuilding procedures
Diagnostics:
Detailed diagnostic procedures for mechanical and electrical issues
Depth:
Expert-level, covering everything from basic maintenance to complete engine rebuilds
Diagrams:
Includes detailed exploded views, wiring diagrams, and schematics
Specifications:
Precise torque values, clearances, measurements, and tolerances
Engine Type:
Naturally Aspirated Inline 5-cylinder Diesel
Engine Code:
OM617.912 (typically)
Displacement:
3.0 Liters (2998 cc)
Horsepower:
Approximately 77-83 hp (SAE Net) depending on year and emissions standards
Torque:
Approximately 130-135 lb-ft (SAE Net) depending on year
Redline:
Approximately 4500 RPM
Injection Type:
Bosch inline mechanical injection pump
Glow Plugs:
4 (one per cylinder, plus an extra for faster warm-up on some models)
Fuel Type:
Diesel fuel (ULSD acceptable, LSD preferred for older engines)
Intake System:
Naturally aspirated, air filter element
Wheelbase:
Approximately 2794 mm (110 inches)
Length:
Approximately 4725 mm (186 inches)
Width:
Approximately 1790 mm (70.5 inches)
Height:
Approximately 1430 mm (56.3 inches)
Curb Weight:
Approximately 1550 - 1650 kg (3417 - 3638 lbs) depending on options
Gross Vehicle Weight Rating:
Approximately 2100 kg (4630 lbs)
Historical Safety:
Known for robust construction and safety features for its era
Brakes:
Front disc, rear drum brakes; optional ABS on later models
Steering Assist:
Recirculating ball, power-assisted standard
Seatbelts:
3-point front seatbelts, lap belts in rear
Construction:
Reinforced passenger cell, crumple zones
Oil Change Interval:
Typically every 5,000 miles or 6 months
Air Filter Replacement:
Every 15,000 miles or as needed based on operating conditions
Fuel Filter Replacement:
Every 15,000 - 30,000 miles or annually
Transmission Service:
Automatic: every 30,000 miles; Manual: inspect clutch, change fluid at higher mileage intervals
Engine Oil Type:
API CD or CE rated diesel engine oil, SAE 15W-40 or 10W-30 (depending on climate)
Engine Oil Capacity:
Approximately 7.5 liters (8 US quarts) with filter change
Coolant Type:
50/50 mixture of Mercedes-Benz approved antifreeze (or equivalent) and distilled water
Brake Fluid Type:
DOT 3 or DOT 4
Diesel Specific:
Glow plug failure, injection pump seal leaks, injector issues, potential for overheating if cooling system is neglected
Chassis Specific:
Rust, worn suspension bushings, vacuum line leaks, HVAC system performance degradation, climate control unit issues
Electrical Specific:
Wiring harness degradation (especially around heat sources), instrument cluster issues, headlight switch problems
Mercedes Benz Legacy:
Renowned for engineering excellence, durability, and innovation since its founding
W123 Introduction:
Introduced in 1976 as a replacement for the W114/W115, marking a significant step in Mercedes-Benz design and engineering
W123 Variants:
Offered in Sedan, Coupe, Estate (wagon), and Long Wheelbase versions. The 300D is a diesel-powered sedan.
Production Period:
1976-1985 for W123 chassis, with the 300D being a core model throughout this period.
Production Volume:
Over 2.7 million W123s produced globally across all body styles, testament to their success
