Positioning:
The Mercedes-Benz 280E W123 represented the pinnacle of mid-size luxury sedans in its era, known for exceptional build quality, comfort, and durability. This manual caters to enthusiasts and owners seeking to maintain and repair these iconic vehicles.
Competitors:
Competed with other premium sedans of the time such as BMW 5 Series (E12/E28), Audi 100, and Volvo 240.
Distinguishing Features:
Robust construction, comfortable and spacious interior, refined ride quality, reliable powertrain, excellent safety features for its time.
Engine:
Engine mechanical, lubrication system, cooling system, fuel system (including fuel injection), ignition system, exhaust system, engine management.
Transmission:
Manual transmission (4-speed and 5-speed), Automatic transmission (3-speed and 4-speed variants), clutch system, driveshaft, differential.
Brakes:
Hydraulic system, front disc brakes, rear disc brakes, parking brake system, ABS (where applicable on later models).
Suspension:
Front independent suspension (MacPherson struts), rear independent suspension (semi-trailing arms), shock absorbers, springs, anti-roll bars.
Steering:
Power steering system, steering column, steering linkage.
Electrical:
Battery, charging system (alternator), starting system, lighting system, instrumentation, wipers and washers, horn, HVAC blower motor, power accessories (windows, locks if equipped).
Body And Chassis:
Chassis construction, body panels, doors, windows, convertible top (if applicable), bumpers, interior trim.
Body And Trim:
Exterior body panels, doors, hood, trunk lid, bumpers, glass replacement, interior trim, seat removal and upholstery.
Heating And Ventilation:
HVAC system operation, blower motor, heater core, A/C compressor and system, ducting.
Wheels And Tires:
Tire types, sizes, pressure recommendations, wheel torque specifications, wheel bearing service.
Maintenance:
Scheduled maintenance, oil changes, filter replacements, fluid checks and changes, lubrication points, tune-ups, belt replacement, spark plug replacement.
Diagnostics:
Troubleshooting guides, symptom-based diagnostics, diagnostic trouble codes (DTCs) for fuel injection and ignition systems, electrical system testing.
Repair:
Detailed step-by-step repair procedures for all major mechanical and electrical components, engine overhaul, transmission rebuilds, brake system repairs, suspension component replacement.
Special Tools:
Identification and usage of specialized tools required for specific repair procedures.
Wiring Diagrams:
Detailed electrical wiring diagrams for all vehicle systems.
Torque Specifications:
Precise torque values for all critical fasteners throughout the vehicle.
Troubleshooting Charts:
Comprehensive charts to diagnose problems based on symptoms.
Depth:
Comprehensive, covering everything from basic preventative maintenance and fluid changes to complete engine and transmission overhauls, advanced electrical diagnostics, and bodywork repairs.
Diagnostic Tools:
Details on using standard hand tools, multimeters, timing lights, and basic pressure testing equipment.
Engine Code:
M110.984 / M110.985
Configuration:
2.8L (2781 cc) Naturally Aspirated Inline-6 (SOHC)
Horsepower Approximate:
182-185 PS (179-182 bhp / 134-136 kW) at 5800 rpm (depending on market and emission controls)
Torque Approximate:
240-245 Nm (177-181 lb-ft) at 4500 rpm
Fuel Delivery:
Bosch K-Jetronic (CIS) Mechanical Fuel Injection
Fuel Type:
Unleaded Gasoline (Premium Octane)
Type:
Pressurized Liquid Cooling System
Oil Capacity Approximate:
7.5 Liters (7.9 US Quarts)
Ignition Type:
Electronic Ignition with Mechanical Distributor
Type:
4-Speed Manual Transmission
Type:
Optional 4-Speed Automatic Transmission (with torque converter)
Automatic Features:
Hydraulic torque converter, typically with a 'Economy'/'Standard' or 'S'/'W' selector.
Automatic Transmission Fluid:
MB Spec 236.2 (Dexron II or equivalent prior to MB Spec 236.3)
Manual Transmission Fluid:
GL-4 Hypoid Gear Oil (SAE 90)
Length:
Approx. 4725-4787 mm (186.0-188.5 in)
Width:
Approx. 1786-1790 mm (70.3-70.5 in)
Height:
Approx. 1430-1440 mm (56.3-56.7 in)
Wheelbase:
Approx. 2795 mm (110.0 in)
Curb Weight Approximate:
1450-1550 kg (3197-3417 lbs)
Gross Vehicle Weight Rating Approximate:
1970-2050 kg (4343-4519 lbs)
Trunk Capacity Approximate:
500-520 Liters (17.7-18.4 cu ft)
Crash Test Results:
No standardized crash test ratings as per modern NTHSA/Euro NCAP protocols were available during this era. However, the W123 chassis was renowned for its structural integrity and safety features for its time.
Active Safety:
Four-wheel disc brakes, robust independent suspension for stable handling, power-assisted steering.
Passive Safety:
Reinforced passenger safety cell, energy-absorbing steering column, padded dashboard, safety belts (three-point front, two-point rear standard, optional three-point rear).
Oil Change Interval:
Typically every 10,000 km (6,200 miles) or 12 months, whichever comes first.
Filter Replacement Interval:
Oil filter with every oil change. Air filter and fuel filter typically every 30,000-50,000 km (18,600-31,000 miles).
Spark Plug Replacement:
Typically every 20,000-30,000 km (12,400-18,600 miles) depending on plug type.
Coolant Flush:
Every 2-3 years or 50,000-60,000 km (31,000-37,000 miles).
Engine Oil Specification:
API SG or higher; SAE 10W-40 or 15W-40 (depending on climate). Consult manual for specific MB approval.
Coolant Specification:
Mercedes-Benz approved coolant (e.g., G05 or equivalent) with appropriate anti-corrosion additives. Mixture of 50% coolant and 50% distilled water.
Brake Fluid Specification:
DOT 3 or DOT 4.
Common Wear Items:
Front suspension bushings and ball joints, flexible brake hoses, fuel distributor diaphragm (K-Jetronic), timing chain (M110 engine requires periodic tensioner replacement/checking), vacuum hoses, door seals, heater blower motor.
Rust Prone Areas:
Wheel arches, rocker panels, jacking points, rear quarter panels, battery tray area.
Mercedes Benz Legacy:
Mercedes-Benz has a long-standing reputation for engineering excellence, luxury, safety, and durability, established in the early 20th century.
W123 Development:
The W123 succeeded the W114/W115 'Stroke Eight' series and was a pivotal model for Mercedes-Benz, cementing its market share in the executive sedan segment. It was designed with a focus on reliability, longevity, and driver comfort.
Manufacturing Location:
Primarily Sindelfingen, Germany.
Production Volume W123:
Over 2.7 million units across all body styles (sedan, coupe, estate, long-wheelbase sedan).
