Target Audience:
Mercedes-Benz owners, independent repair shops, classic car enthusiasts.
Value Proposition:
Provides in-depth technical information essential for maintaining and repairing the robust W123 chassis and its OM616 diesel engine, often surpassing generic repair guides in detail.
Comprehensiveness:
Covers all aspects of the vehicle's systems with a focus on practical repair and maintenance.
Accuracy:
Derived from official Mercedes-Benz technical documentation.
Engine Mechanical:
Complete disassembly, inspection, repair, and reassembly of engine components.
Fuel System:
Diesel injection system (Bosch), fuel pump, injectors, lines, and filters.
Cooling System:
Radiator, water pump, thermostat, hoses, and fan.
Exhaust System:
Exhaust manifold, catalytic converter (if applicable), muffler, and pipes.
Ignition System:
Glow plug system and diagnostics.
Transmission Manual:
Clutch, gearbox (4-speed or 5-speed manual), driveshafts.
Transmission Automatic:
Automatic transmission (e.g., 4-speed 722.1 or 722.3), torque converter, valve body.
Suspension Front:
Independent suspension, control arms, ball joints, springs, shock absorbers.
Suspension Rear:
Independent suspension, semi-trailing arms, springs, shock absorbers.
Steering System:
Steering box, linkages, power steering pump (if equipped).
Brake System:
Front disc brakes, rear drum brakes, master cylinder, calipers, wheel cylinders, parking brake.
Electrical System:
Battery, alternator, starter motor, wiring diagrams, lighting, fuses, relays.
Bodywork And Chassis:
Body panel repair, door mechanisms, window regulators, underbody protection.
Heating And Ventilation:
HVAC system, heater core, blower motor, air conditioning (if equipped).
Interior Trim:
Dashboard, seats, door panels, carpet replacement.
Troubleshooting:
Diagnostic procedures and common problem resolution for all systems.
Type:
Factory Service Manual / Workshop Manual
Format:
Digital (likely PDF)
All Systems:
Covers all major mechanical, electrical, and body systems.
Maintenance Procedures:
Regular scheduled maintenance, oil changes, filter replacements, tune-ups.
Repair Procedures:
Step-by-step instructions for component repair and replacement.
Rebuild Procedures:
Detailed instructions for engine and transmission rebuilds.
Diagnostic Procedures:
Troubleshooting guides with symptom-based diagnosis.
Specification Data:
Torque specifications, clearances, fluid capacities, timing data.
Depth:
Comprehensive, covering everything from basic adjustments to complete overhauls.
Engine Type:
Naturally Aspirated Inline 4-Cylinder Diesel
Engine Code:
OM616.912 (typical for this era 240 D)
Displacement:
2.4 Liters (2399 cc)
Horsepower Approx:
70-72 hp @ 4000 rpm
Torque Approx:
100-103 lb-ft @ 2200 rpm
Injection System:
Bosch Inline Injection Pump (e.g., PES 4M55/220)
Injectors:
Bosch Diesel Injectors
Cooling Method:
Liquid Cooling
Oil Capacity Approx:
7.5 Liters (with filter)
Recommended Oil Viscosity:
SAE 15W-40 Diesel (e.g., MB 228.1 specification)
Type:
4-speed Manual (usually)
Type:
4-speed Automatic (e.g., 722.1 or 722.3)
Clutch Type:
Single dry plate clutch
Manual Transmission Fluid:
GL-4 Gear Oil (e.g., MB 235.0 specification, SAE 80W-90)
Automatic Transmission Fluid:
Dexron III equivalent (check manual for exact MB specification, e.g., MB 236.1)
Crash Test History:
While official modern crash test ratings for this era are scarce, Mercedes-Benz W123 models were renowned for their robust build quality and safety features for their time.
Braking:
Front disc brakes, rear drum brakes with dual hydraulic circuits.
Chassis Design:
Reinforced safety cage, crumple zones.
Steering Column:
Collapsible steering column.
Oil Change Interval:
Every 5,000 - 7,500 miles or 6 months (check specific manual recommendations).
Fuel Filter Replacement:
Every 15,000 - 20,000 miles.
Air Filter Replacement:
Every 15,000 - 20,000 miles.
Valve Adjustment:
Periodically, as specified in the manual (e.g., every 20,000-30,000 miles).
Coolant Type:
Ethylene Glycol based coolant (e.g., MB specification 325.0 or similar).
Brake Fluid Type:
DOT 3 or DOT 4.
Diesel Injection Pump Wear:
Wear in injection pump components can lead to starting issues or rough running.
Rust Corrosion:
Common on older Mercedes-Benz models, particularly in wheel arches, sills, and around windows.
Vacuum System Leaks:
Vacuum leaks can affect central locking, door locks, and headlight leveling.
Prechamber Glow Plugs:
Failure of prechamber glow plugs can cause hard starting in cold weather.
Brand Focus:
Mercedes-Benz is synonymous with engineering excellence, durability, and luxury, particularly in the diesel segment.
W123 Significance:
The W123 series (1976-1985) is celebrated for its legendary reliability and longevity, setting a benchmark for executive sedans. The 240 D represented the entry-level diesel option within this esteemed lineup.
Production Period 240D:
1976-1985 (covering the specific 1981-1983 years)
