Market Position:
The Mercedes-Benz W123 series, particularly the T-Model (wagon), was positioned as a durable, reliable, and luxurious mid-size executive vehicle with strong practicality. The 240TD variant offered exceptional fuel economy and longevity, making it a favored choice for those prioritizing economy and reliability over outright performance.
Competitors:
Competed against other European premium wagons like the Audi 100 Avant, Volvo 240 DL Wagon, and BMW E28 Touring (though the latter was less common). Its robust engineering and diesel engine options set it apart in terms of long-term durability and running costs.
Key Features:
Renowned for its over-engineered construction, legendary durability, comfortable ride, spacious interior, and the efficient OM616 diesel engine. The T-Model added significant practicality with its large cargo area and versatile seating.
Covered Years:
1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985
Covered Models:
Mercedes-Benz 240TD (all W123 T-Model variants)
Estimated Page Count:
Approximately 800-1200 pages (typical for comprehensive factory-level manuals of this era, exact number depends on specific publisher)
Manual Type:
Service and Repair Manual
Language:
English (common for aftermarket manuals, original factory may vary)
Engine:
Detailed overhaul, diagnosis, and repair procedures for the OM616 (2.4L Diesel) engine, including fuel injection system, cooling system, lubrication, and emissions.
Transmission:
Coverage of manual and automatic transmissions (e.g., 4-speed manual, 3-speed automatic 722.1, 4-speed automatic 722.3), including repair, adjustment, and fluid service.
Drivetrain:
Rear axle differential, driveshafts, universal joints, and wheel bearings.
Suspension:
Front independent suspension (double wishbone), rear independent suspension (semi-trailing arm), shock absorbers, springs, and alignment procedures.
Steering:
Power steering system diagnosis and repair, steering box, tie rods, and steering column components.
Brakes:
Front disc brakes, rear drum brakes, hydraulic system, parking brake, caliper and wheel cylinder overhaul, fluid replacement.
Electrical System:
Wiring diagrams, starter, alternator, battery, lighting system, ignition (for gasoline variants, less so for diesel), gauges, and accessory circuits.
Body And Interior:
Body panel removal and installation, door mechanisms, window regulators, seat adjustments, interior trim, climate control system (heater, A/C if equipped).
Fuel System:
Fuel tank, fuel lines, fuel filter, lift pump, and injection pump for the diesel engine.
Maintenance:
Scheduled maintenance intervals, oil changes, filter replacements, fluid checks and changes, lubrication points.
Troubleshooting:
Diagnostic flowcharts and step-by-step guides for common problems and symptoms across all major systems.
Repair:
Detailed instructions for component removal, overhaul, reassembly, and installation.
Diagnostics:
Engine performance diagnosis, electrical system testing, mechanical component testing.
Specifications:
Torque specifications for critical fasteners, engine clearances, fluid capacities, electrical component resistance values.
Depth:
Comprehensive, covering basic maintenance to complete engine and transmission rebuilds. Factory-level detail with exploded diagrams and service bulletins referenced.
Engine Type:
Inline 4-cylinder Diesel
Displacement:
2.4 Liters (2399 cc)
Bore X Stroke:
87.0 mm x 92.4 mm
Compression Ratio:
21.0:1
Horsepower:
70-72 PS (DIN) / 69-71 hp @ 4200 rpm (approx.)
Torque:
137-141 Nm (101-104 lb-ft) @ 2400 rpm (approx.)
Fuel Injection:
Bosch inline injection pump with indirect injection (pre-chamber combustion).
Cooling Type:
Liquid-cooled, pressurized system.
Oil Capacity:
Approx. 6.5 Liters (6.9 US Quarts) with filter change.
Standard Transmission:
4-speed Manual Transmission
Optional Transmission:
3-speed Automatic (722.1) or 4-speed Automatic (722.3) Transmission
Clutch:
Single dry plate clutch (manual).
Automatic Features:
Torque converter, hydraulic control, often with a vacuum modulator for shift point adjustment.
Manual Transmission Fluid:
MB 235.0 (e.g., SAE 80W-90 GL-4 gear oil)
Automatic Transmission Fluid:
MB 236.2 (Dexron-II equivalent or compatible)
Length:
Approx. 4765 mm (187.6 in)
Width:
Approx. 1786 mm (70.3 in)
Height:
Approx. 1460 mm (57.5 in)
Wheelbase:
Approx. 2850 mm (112.2 in)
Front Track:
Approx. 1460 mm (57.5 in)
Rear Track:
Approx. 1444 mm (56.8 in)
Seating Capacity:
5-7 passengers (depending on optional rear-facing seats)
Cargo Volume:
Substantial cargo capacity, variable with rear seats folded (specific figures often not quoted by manufacturer in this era, but known to be large).
Curb Weight:
Approx. 1450-1550 kg (3197-3417 lbs), varies with equipment.
Gross Vehicle Weight Rating:
Approx. 2000-2100 kg (4409-4630 lbs)
Towing Capacity:
Typically around 1500 kg (3300 lbs) with braked trailer, check specific vehicle VIN.
Crash Test Data:
No standardized crash test ratings as we know them today (e.g., NHTSA/Euro NCAP). However, Mercedes-Benz of this era was known for robust structural integrity and a focus on passive safety features.
Active Safety:
Four-wheel disc brakes (optional, some had front disc/rear drum), power steering, strong chassis construction.
Passive Safety:
Reinforced safety cage, energy-absorbing steering column, safety glass all around, padded dashboard and interior surfaces, three-point seatbelts (front, rear often lap belts).
Front Brakes:
Ventilated Disc Brakes (standard on most 240TD models).
Rear Brakes:
Drum Brakes.
Infotainment System:
Basic for its era: Analog radio (AM/FM), cassette player optional. Focus was on mechanicals and comfort, not electronics.
Driver Assistance Features:
Limited to power steering and optional cruise control (on some models). ABS was not commonly available on diesel variants of this generation.
Connectivity Features:
None (no provisions for modern connectivity).
Climate Control System:
Manual ventilation and heating system, with optional (and highly sought-after) factory-installed air conditioning. Vacuum-operated flaps for air distribution.
Oil Change Interval:
Every 5,000-10,000 km (3,000-6,000 miles) or annually, depending on driving conditions. Refer to manual for exact spec.
Air Filter Replacement:
Every 20,000-40,000 km (12,000-25,000 miles).
Fuel Filter Replacement:
Every 20,000-30,000 km (12,000-18,000 miles).
Transmission Service Interval:
Automatic: Every 40,000-60,000 km (25,000-37,000 miles). Manual: Less frequent, check for leaks.
Engine Oil Specification:
API CD or CE rated diesel engine oil, viscosity typically 15W-40 or 10W-40 depending on climate. MB-Approval 228.1 or 228.3.
Coolant Specification:
Mercedes-Benz Spec 325.0 (Glycol-based antifreeze, typically 50/50 mix with distilled water).
Brake Fluid Specification:
DOT 3 or DOT 4 (check manual, typically specified by MB).
Common Issues:
Diesel injection pump leaks (especially shaft seal), vacuum leaks affecting power steering and climate control, injector seal leaks, potential for rust in common W123 areas (wheel arches, sills, under battery tray), valve adjustments may be needed, glow plug issues.
Diesel Specific Maintenance:
Regular bleeding of the fuel system after filter changes, proper glow plug operation is crucial for cold starts.
Brand Heritage:
Mercedes-Benz has a long history dating back to the invention of the automobile, consistently associated with engineering excellence, luxury, and durability.
W123 Evolution:
The W123 series (introduced 1976) replaced the W114/W115 series. It was famously over-engineered and built to last, with significant refinements over its production run (until 1985 for sedans/coupes, 1986 for wagons). The T-Model (wagon) was introduced in 1977 and was the first station wagon offered by Mercedes-Benz.
Production Years:
W123 T-Model: 1977-1986. The 240TD model was produced throughout this period.
Manufacturing Locations:
Primarily Sindelfingen, West Germany.
Awards:
While the W123 series as a whole did not receive specific 'awards' in the modern sense, it was consistently praised in automotive press for its build quality, reliability, and longevity. It achieved a strong reputation for being a 'car for life' and a wise investment for those seeking durable transportation.
Reliability Reputation:
Exceptional. The W123 is considered one of the most reliable and durable Mercedes-Benz models ever produced, with many examples exceeding 500,000 miles with proper maintenance.
