Era Significance:
The W123 generation represented Mercedes-Benz's commitment to build quality, durability, and engineering excellence in the mid-to-late 1970s and early 1980s.
Contemporary Rivals:
Competed against luxury sedans from BMW (e.g., 5 Series), Audi, Jaguar, and Volvo, often praised for its robust build and longevity.
Engineering Philosophy:
Over-engineered for durability and long-term reliability, reflecting Mercedes-Benz's 'best or nothing' ethos of the period.
Safety Emphasis:
Introduced significant safety advancements for its time, including improved crash structures and driver controls.
Engine Mechanical:
Complete engine overhaul, cylinder head, pistons, crankshaft, camshafts, timing components, lubrication system, cooling system
Engine Electrical:
Ignition system (Bosch K-Jetronic fuel injection and ignition control), starter system, alternator, battery
Fuel System:
Bosch K-Jetronic fuel injection system diagnostics, fuel pump, fuel filter, injectors, fuel pressure regulator, fuel tank
Transmission:
4-speed Manual Transmission (G4/27), 4-speed Automatic Transmission (722.1) - overhaul, adjustments, fluid service
Drivetrain:
Clutch (manual), driveshaft, universal joints, rear axle differential, half-shafts
Suspension:
Front independent suspension (double wishbone), rear independent suspension (semi-trailing arm), shock absorbers, springs, ball joints, bushings
Steering:
Power steering system (Bosch recirculating ball), steering column, steering gear, tie rods, idler arm
Brakes:
Front ventilated discs, rear discs, brake system hydraulics, master cylinder, brake calipers, brake pads, brake fluid specifications, parking brake
Electrical System:
Wiring diagrams, lighting system, instruments, gauges, switches, fuses, relays, battery, starter, alternator
Body And Chassis:
Body construction, door mechanisms, window regulators, hinges, latches, interior trim, exterior trim, corrosion protection
HVAC:
Heating system, ventilation system, air conditioning (optional) system
Maintenance:
Scheduled maintenance, oil changes, filter replacements, spark plug replacement, fluid checks and top-ups, belt inspections and replacement
Troubleshooting:
Diagnostic procedures for common issues, symptom-based troubleshooting guides
Repair:
Step-by-step instructions for component removal, repair, and reinstallation across all major systems
Diagnostics:
Detailed diagnostic procedures for engine management, fuel injection, ignition, and electrical systems
Adjustments:
Valve adjustments, idle speed adjustments, ignition timing adjustments, parking brake adjustments
Depth Of Coverage:
Comprehensive - covers everything from routine maintenance to full engine and transmission rebuilds, including detailed specifications and tolerances.
Diagnostic Tools:
Information on specialized tools and diagnostic equipment used by Mercedes-Benz technicians during the W123 era.
Engine Type:
Inline-6 Cylinder, Naturally Aspirated
Engine Code:
M110.984 (or similar variants)
Displacement:
2746 cc (2.8 Liters)
Bore X Stroke:
86.0 mm x 78.7 mm
Compression Ratio:
8.7:1 (typical for Euro spec, may vary)
Horsepower:
185 PS (metric horsepower) @ 5800 rpm (approx. 182 bhp)
Torque:
240 Nm (approx. 177 lb-ft) @ 4000 rpm (approx.)
Fuel Injection:
Bosch K-Jetronic (CIS - Continuous Injection System) mechanical fuel injection
Fuel Type:
Unleaded Gasoline (Premium Octane Recommended)
Cylinder Configuration:
Inline 6
Valve Train:
Single Overhead Camshaft (SOHC) per bank, 2 valves per cylinder (M110 engine is DOHC - Double Overhead Camshaft, 4 valves per cylinder, correction from common assumption)
Standard Transmission Type:
4-Speed Manual (G4/27)
Optional Transmission Type:
4-Speed Automatic (722.1)
Automatic Transmission Mode:
Standard (P, R, N, 3, 2) or Optional (P, R, N, D, 2, 1) shift patterns depending on year/market.
Automatic Transmission Fluid:
MB 236.6 (e.g., Dexron II compatible fluids of the era)
Crash Test Data:
While formal ratings like NHTSA's were less standardized in this era, the W123 was renowned for its robust construction and safety cage, contributing to excellent occupant protection.
Braking System:
Four-wheel disc brakes, typically with front ventilated discs; power assisted.
Steering System:
Recirculating ball power steering.
Body Structure:
Reinforced passenger compartment, crumple zones front and rear.
Seat Belts:
Standard three-point seat belts (front); lap belts often standard in rear.
Steering Column:
Collapsible steering column.
Oil Change Interval:
Typically every 7,500 - 10,000 miles (12,000 - 15,000 km) or annually.
Major Service Interval:
Every 30,000 - 50,000 miles (50,000 - 80,000 km) for items like spark plugs, fuel filters, and transmission service.
Engine Oil Specification:
API SG or higher, SAE 15W-40 or 10W-40 (check owner's manual for specific viscosity based on climate).
Coolant Specification:
Mercedes-Benz approved coolant (e.g., G48 or equivalent ethylene glycol based with appropriate corrosion inhibitors), 50/50 mix with distilled water.
Brake Fluid Specification:
DOT 3 or DOT 4 brake fluid.
Power Steering Fluid:
MB 236.3 power steering fluid or equivalent hydraulic fluid.
Common Wear Items:
Rubber bushings (suspension, engine mounts), vacuum lines (for HVAC and central locking), fuel distributor seals (K-Jetronic), ignition components (rotor, cap, points if applicable).
Potential Corrosion:
Rust can affect wheel arches, door bottoms, and jacking points; thorough inspection is recommended.
K Jetronic Quirks:
Can develop issues with fuel pressure regulator, air flow sensor, or injectors leading to rough running or starting problems.
Mercedes Benz Legacy:
Built upon Mercedes-Benz's reputation for engineering, quality, and durability established in post-war decades.
W123 Introduction:
Introduced in 1976 as the successor to the W114/W115 range, offering a more modern design and improved amenities.
280E Positioning:
The 280E was positioned as a high-end, performance-oriented model within the W123 lineup, known for its smooth inline-six engine.
Production Years:
1976 - 1985
Manufacturing Locations:
Primarily West Germany, with assembly plants in other global locations.
Sales Volume Impact:
The W123 was a significant commercial success for Mercedes-Benz, with over 2.7 million units produced across all body styles, solidifying its reputation for longevity.
