Positioning:
The Mercedes-Benz W123 series, particularly the robust 240D diesel variant, was renowned for its durability, reliability, and engineering excellence in its era. It appealed to buyers prioritizing longevity and economical operation over outright performance.
Competitors:
Competed against other premium European sedans and luxury marques that offered diesel engines, though few matched the W123's reputation for build quality and longevity. Key competitors included BMW's 5-series diesels (though less common and often less fuel-efficient) and various luxury sedans from manufacturers like Volvo and Audi in different markets.
Vehicle Highlights:
Iconic 'brick' design, solid construction, comfortable ride, exceptional build quality, the naturally aspirated 616.912 diesel engine known for its extreme longevity and fuel efficiency. Served as a dependable workhorse and long-distance cruiser.
Manual Benefit:
This manual provides dealership-level repair and maintenance information, empowering owners and independent mechanics to perform a wide range of tasks accurately, saving significant costs compared to authorized dealer service.
General Maintenance Service:
00 - Maintenance, service, technical data; General descriptions; Operating instructions; General considerations concerning service products (fluids, etc.); Jacking-up, towing-off, laying-up vehicle
Engine Mechanical:
01 - Engine, removal and installation; Crankcase, cylinder head, engine breathing; 03 - Crank assembly; 05 - Engine timing, valves
Fuel System:
07.1 - Diesel injection system; 07.2 - Carburetor system (Not applicable to 240D); 07.3 - Mechanically and mechanically/electronically controlled gasoline injection system (Not applicable to 240D); 07.4 - Electronically controlled gasoline injection system (Not applicable to 240D); 47 - Fuel system
Intake Exhaust Emissions:
09 - Air cleaner, intake air preheater; Exhaust gas turbocharger (Not applicable to standard 240D); 14 - Intake manifold, exhaust manifold; Engine brake, emission control system
Engine Electrical:
15 - Electrical system engine (ignition system, preheating system, starter, alternator)
Engine Support Systems:
13 - Air compressor, belt drives; 18 - Engine lubrication, engine oil cooler; 20 - Engine cooling system, coolant hoses, radiator; 22 - Engine mounting
Drivetrain:
25 - Clutch; 26 - Manual transmission, power take-offs; 27 - Automatic transmission; 28 - Transfer case (Not applicable to 240D); 29 - Pedals; 30 - Throttle control; 300 Adjusting throttle linkage; 310 Removal and installation of engine longitudinal regulating shaft; 320 Removal, installation and adjustment of front wall regulating shaft; 330 Removal and installation of accelerator pedal
Chassis Suspension Steering:
31 - Frame; Trailer operation; 32 - Suspension; 33 - Front axle; 35 - Rear axle, trailing axle; 40 - Wheels, chassis measurements; 46 - Steering
Brakes:
42 - Brakes - hydraulical and mechanical system; 43 - Brakes - pneumatic system and auxiliary brakes (Not applicable to standard 240D)
Exhaust Propulsion:
41 - Propeller shaft; 49 - Exhaust system, heat shield, outer
Body Electrical Accessories:
54 - Electrical system; Equipment and instruments; Speed control systems (Not applicable to standard 240D); 82 - Electrical system body; Radio, windshield washer system, light range regulator; 83 - Climate control; 86 - Emergency equipment, sanitary equipment, kitchen (Generally not covered in detail for this model); 88 - Attachments, outside flaps
Body Structure Interior:
60 - Body, general; 61 - Understructure; 62 - Front end and front wall; 63 - Side wall; 64 - Rear wall and rear end; 65 - Roof; 67 - Glass (panes) and windows; 68 - Interior equipment; 72 - Doors; 75 - Trunk lid, fuel flap; 77 - Slide roof (sun roof), top, racks; 91 - Seats, cots, restraint systems; 94 - Body noises, sound insulation; 97 - Body sealing, anti-corrosion protection; 98 - Paintwork
Auxiliary Systems Documentation:
55 - Auxiliary drives, hydraulic and articulated systems; 58 - Tools, test instruments, equipment; 99 - Technical literature; Validity list, administration
Manual Types Included:
Service Repair Manual, Maintenance Manual (MM), Owner's Manual (OM) references likely
Estimated Pages:
Likely 1000+ pages, typical for comprehensive workshop manuals of this era and detail level.
Type:
Factory Service Manual (FSM) / Workshop Manual
Powertrain:
Engine mechanicals (cylinder head, block, crankshaft, valvetrain), diesel injection system, lubrication, cooling, fuel system, clutch, manual and automatic transmissions, driveshafts.
Chassis:
Frame, suspension components (front and rear axles, control arms, springs, shocks), steering system, wheels, tires, chassis alignment.
Brakes:
Hydraulic brake system (master cylinder, wheel cylinders/calipers, lines, hoses), parking brake.
Electrical:
Engine electrical (starter, alternator, preheating system), lighting, instruments, gauges, wiring diagrams for various body and engine functions, windshield washer system.
Body:
Body structure (frame, panels, understructure), doors, windows, glass, interior trim, seats, trunk lid, fuel filler flap, sunroof, exterior trim, paint, anti-corrosion.
HVAC:
Climate control systems, heating, ventilation.
Maintenance:
Scheduled maintenance tasks, fluid changes, filter replacements, lubrication points, inspections.
Diagnostics:
Troubleshooting guides, symptom-based diagnostics, common issues and solutions for engine, drivetrain, chassis, and electrical systems.
Repair Rebuild:
Step-by-step removal, installation, and overhaul procedures for all major components and systems.
Adjustments:
Adjustment procedures for engine timing, valves, injection pump, throttle linkages, brakes, clutch, etc.
Technical Data:
Specifications, tolerances, torques, fluid capacities, wiring diagrams, schematics, diagnostic codes (if applicable).
Depth:
Comprehensive, covering everything from routine maintenance to complete engine rebuilds and bodywork repairs, suitable for professional mechanics and advanced DIYers.
Transmission Type:
4-speed Manual Transmission
Transmission Type:
Optional 4-speed Automatic Transmission (often referred to as 4G-TRONIC)
Clutch Type:
Single dry plate clutch (for manual transmission)
Manual Transmission Fluid:
API GL-4 SAE 80W-90 or 75W-90 gear oil (refer to manual for exact spec).
Automatic Transmission Fluid:
MB Specification 236.1 or 236.2 Dexron-II equivalent (check manual for exact MB spec).
Safety Features Era:
While formal crash testing standards were different, Mercedes-Benz had a strong emphasis on passive safety, including a strong safety cell, energy-absorbing steering column, and robust build quality. Features like dual-circuit brakes were standard.
Active Safety:
Four-wheel disc brakes (front discs, rear drums or all-around discs depending on later models/options), power steering (often recirculating ball).
Passive Safety:
Reinforced passenger compartment, laminated windshield, safety glass all around, collapsible steering column, padded dashboard.
Oil Change Interval:
Typically every 5,000-7,500 miles (8,000-12,000 km) or annually, depending on driving conditions. Consult the OM for precise intervals. (Manual covers this).
Fuel Filter Replacement:
Every 15,000-20,000 miles (24,000-32,000 km) or as per manual recommendations. (Manual covers this).
Air Filter Replacement:
Every 10,000-15,000 miles (16,000-24,000 km) or as needed based on inspection. (Manual covers this).
Engine Oil Specification:
API CD or CE rated diesel engine oil, SAE 15W-40 or 10W-40 depending on climate. (Manual covers exact specs and capacities).
Coolant Specification:
Propylene glycol-based coolant (typically a 50/50 mix with distilled water) meeting Mercedes-Benz specifications for corrosion protection. (Manual covers exact spec).
Brake Fluid Specification:
DOT 3 or DOT 4 hydraulic brake fluid. (Manual covers exact spec).
Common Wear Items:
Vacuum lines (for central locking, climate control, etc.), glow plug system, diesel injection pump seals, front suspension bushings, rear axle mounting points, rust (especially wheel wells, rocker panels, undercarriage). (Manual provides diagnostic procedures for these).
Engine Longevity:
The OM616 engine is renowned for its ability to exceed 300,000 miles (480,000 km) with proper maintenance, making it a highly desirable classic diesel engine.
Mercedes Benz Legacy:
Mercedes-Benz has a long history of engineering innovation, luxury, and durability, dating back to the invention of the automobile. The W123 continued this legacy with a focus on reliability and build quality.
W123 Development:
The W123 was introduced in 1975 as the successor to the W114/W115 series. It was designed to be more robust and comfortable, with a focus on improved aerodynamics and safety. The 240D variant was a key model for its fuel efficiency and long-term reliability, especially for fleet and long-distance use.
Production Period:
1975-1985 (W123 series); 240D variant produced throughout this period.
Manufacturing Sites:
Primary manufacturing in Stuttgart, Germany, with assembly plants in other countries as well.
