Market Segment:
Mid-size luxury sedan/saloon.
Key Competitors:
BMW 5 Series (E28), Audi 100/200, Volvo 240/700 Series, Jaguar XJ Series.
Brand Reputation:
Renowned for build quality, durability, safety, and engineering excellence.
Model Philosophy:
Emphasis on robust engineering, comfort, and a sophisticated driving experience, often referred to as 'over-engineered'.
Covered Years:
1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985
Estimated Page Count:
Approximately 500-700 pages (typical for comprehensive workshop manuals of this era)
Manual Type:
Workshop Service Manual / Repair Manual
Engine Systems:
Engine mechanical (M110 inline-6), fuel injection (Bosch K-Jetronic), ignition system, cooling system, lubrication system, emission controls.
Transmission Systems:
4-speed manual transmission, 4-speed automatic transmission (optional), clutch, driveshaft, differential.
Chassis And Suspension:
Front suspension (independent, double wishbone), rear suspension (independent, semi-trailing arm), steering system (power assisted), braking system (front discs, rear discs).
Electrical And Electronics:
Wiring diagrams, battery, charging system (alternator), starting system, lighting system, instrument cluster, HVAC controls, power accessories (windows, locks, antenna).
Body And Interior:
Body structure, exterior trim, doors, windows, seating, interior trim, HVAC system.
Maintenance Procedures:
Scheduled maintenance, oil changes, filter replacements, spark plug replacement, fluid checks and changes, belt inspections and replacement.
Repair Procedures:
Engine overhaul, transmission overhaul, brake caliper rebuild, suspension component replacement, steering gear repair, electrical component diagnosis and replacement.
Troubleshooting Guides:
Diagnostic flowcharts for common driveability issues, electrical faults, and mechanical problems.
Special Tools And Techniques:
Identification and usage of specialized Mercedes-Benz tools required for specific repairs.
Depth Of Coverage:
Comprehensive, covering routine maintenance, component-level repair, complete engine and transmission rebuilds, and detailed diagnostic procedures.
Engine Code:
M110.984 (likely for 280E)
Engine Type:
Inline 6-cylinder, SOHC (Single Overhead Camshaft)
Displacement:
2746 cc (2.7 Liters)
Horsepower Gross:
185 PS (182 hp; 136 kW) @ 5800 rpm (approximate, may vary slightly by market/year)
Torque Gross:
245 Nm (181 lb-ft) @ 4000 rpm (approximate)
Fuel Delivery:
Bosch K-Jetronic (CIS - Continuous Injection System) mechanical fuel injection.
Fuel Type:
Unleaded gasoline (RON 95 or higher recommended)
Ignition Type:
Breakerless electronic ignition (Bosch)
Standard Gearbox:
4-speed manual transmission
Optional Gearbox:
4-speed automatic transmission (Optional, often referred to as 'Hydrak' or '4G-Tronic')
Transmission Fluid Spec:
MB 236.2 (for Automatic Transmission)
Clutch Type:
Single dry plate, hydraulically operated (for manual transmission)
Differential Type:
Hypoid rear axle differential
Crash Test Results:
While formal crash test ratings as we know them today were less common, Mercedes-Benz vehicles of this era were designed with advanced safety features for their time, including a strong safety cage, crumple zones, and padded interior.
Braking System Type:
Power-assisted hydraulic disc brakes front and rear.
Steering Assistance:
Power steering
Seatbelts:
Three-point inertia-reel seat belts (standard in front, often optional in rear).
Steering Column:
Collapsible steering column.
Dashboard Design:
Padded dashboard and steering wheel.
Audio System:
Factory-installed AM/FM radio with cassette player was common, often with optional premium sound system.
Dashboard Controls:
Analog gauges for speedometer, tachometer, fuel level, engine temperature, oil pressure, and clock. HVAC controls integrated into the center console.
Cruise Control:
Optional cruise control system available on many models.
Connectivity Features:
No modern connectivity features like Bluetooth or USB. Primarily mechanical and electrical systems.
Oil Change Interval:
Typically every 10,000 km (6,000 miles) or 12 months, whichever comes first.
Major Service Intervals:
Significant inspections and component checks recommended at 30,000 km (20,000 miles) or 24 months.
Engine Oil Spec:
API SG or higher; Viscosity: SAE 15W-40 or 10W-40 depending on climate (refer to manual for specific recommendations).
Coolant Spec:
Mercedes-Benz approved coolant concentrate (e.g., G48) mixed with distilled water in a 50/50 ratio.
Power Steering Fluid Spec:
MB 236.3 (ATF Dexron II or equivalent)
Fuel Filter Replacement:
Recommended every 20,000 km (12,000 miles) for K-Jetronic system.
Air Filter Replacement:
Recommended every 10,000-15,000 km (6,000-9,000 miles).
Common Wear Items:
Brake wear, suspension bushings, exhaust system, fuel injection system components (e.g., fuel distributor, injectors), vacuum hoses, idle control valve.
Electrical Quirks:
Aging wiring harnesses, potential issues with vacuum-operated systems, headlight switch failures.
Body Corrosion:
Susceptible to rust, particularly in wheel arches, rocker panels, and around window seals, depending on climate and maintenance.
Manufacturer Origin:
Germany
Brand Focus:
Pioneering automotive technology, luxury, and safety.
W123 Introduction:
Introduced in 1975 as the successor to the W114/W115 series.
W123 Body Styles:
Available as Sedan (Saloon), Coupe, Estate (Station Wagon), and Limousine. The 280E specifically refers to the four-door sedan.
W123 Design Philosophy:
Designed for exceptional durability, comfort, and market appeal, becoming a benchmark for automotive engineering and reliability.
Production Period:
1975-1985
Total W123 Production:
Over 2.7 million units across all body styles.
Key Markets:
Europe, North America, Global.
