Engine:
Engine mechanicals, fuel injection (Bosch K-Jetronic), ignition system, cooling system, lubrication system, engine diagnostics and troubleshooting.
Transmission:
Manual and Automatic (4-speed and 5-speed manual, 4-speed automatic) transmission overhaul, repair, adjustments, and fluid specifications.
Drivetrain:
Clutch, driveshafts, differential, rear axle assembly, wheel bearings, lubrication.
Brakes:
Hydraulic system, disc brakes (front and rear), brake calipers, master cylinder, brake lines, parking brake, ABS (if equipped for later models), troubleshooting.
Suspension:
Front independent suspension (double wishbone), rear independent suspension (semi-trailing arm), shock absorbers, springs, sway bars, steering knuckle, bushings, alignment specifications.
Steering:
Power steering system, steering box, tie rods, steering column, steering wheel removal and installation, lubrication.
Electrical System:
Wiring diagrams, battery, alternator, starter motor, lighting system, instrumentation, horn, wipers, power windows, central locking, troubleshooting, fuse/relay identification.
Fuel System:
Fuel tank, fuel pump, fuel lines, fuel filter, fuel injectors, fuel pressure regulation, emissions control systems (e.g., air injection).
Cooling System:
Radiator, fan, water pump, thermostat, heater core, coolant specifications, flushing and filling procedures.
Exhaust System:
Exhaust manifold, catalytic converter (if applicable), mufflers, pipes, hangers, gaskets.
Body And Interior:
Body panel removal and installation, doors, windows, seats, dashboard, trim, sound deadening, rust prevention and repair.
Climate Control:
HVAC system, air conditioning service, heater controls, blower motor, evaporator, condenser, refrigerant types and capacities.
Maintenance:
Scheduled maintenance (oil changes, filter replacements, spark plug replacements, drive belt checks), lubrication points, fluid level checks, tune-up procedures.
Troubleshooting:
Systematic diagnostic procedures for common and uncommon faults across all major vehicle systems, symptom-based diagnosis.
Repair:
Step-by-step instructions for component removal, disassembly, inspection, repair, reassembly, and installation.
Overhaul:
Detailed procedures for complete engine, transmission, and differential overhauls, including internal component specifications and clearances.
Adjustment:
Precise procedures for adjusting ignition timing, fuel mixture, valve clearances, clutch engagement, and brake systems.
Diagnostics:
Diagnostic charts, fault codes interpretation (where applicable), and testing procedures for electrical and mechanical components.
Specifications:
Torque specifications for all fasteners, engine clearances, alignment data, fluid capacities, and component tolerances.
Depth:
Comprehensive, suitable for professional mechanics and advanced DIY enthusiasts. Covers everything from basic maintenance to complete engine and transmission rebuilds.
Crash Test Data:
While formal US NHTSA/IIHS ratings for this era are scarce, the W123 was renowned for its robust safety cage, crumple zones, and strong pillar design, earning a reputation for exceptional passive safety.
Brakes:
Four-wheel disc brakes (ventilated front, solid rear), ABS optional from 1980 onwards.
Steering:
Recirculating ball steering system with power assist.
Body Construction:
Reinforced safety cell, energy-absorbing steering column, laminated windshield, shatter-resistant side and rear glass.
Seat Belts:
Front 3-point inertia reel seatbelts, rear lap belts standard. Optional rear 3-point belts on some models.
Airbags:
Not available on this model.
Oil Change:
Typically every 7,500 - 10,000 miles (12,000 - 15,000 km) or 12 months, whichever comes first.
Air Filter:
Inspect every 15,000 miles (24,000 km), replace as needed or every 30,000 miles (48,000 km).
Fuel Filter:
Replace every 30,000 miles (48,000 km).
Spark Plugs:
Replace every 30,000 miles (48,000 km) or as recommended by the manual (e.g., Bosch W8AC or equivalent).
Coolant Flush:
Every 2-3 years or 30,000-45,000 miles (48,000-72,000 km).
Valve Adjustment:
Check/adjust every 30,000 miles (48,000 km) or as per manual recommendations for the M110 engine.
Engine Oil:
SAE 10W-40 or 10W-50 API SF/SG (or equivalent MB Specification like 227.1 or 228.1, consult specific manual)
Coolant:
Ethylene glycol based antifreeze with corrosion inhibitors. Mixture of 50% antifreeze and 50% distilled water.
Brake Fluid:
DOT 3 or DOT 4 (low viscosity) hydraulic brake fluid.
Power Steering Fluid:
MB Specification 236.3 (e.g., Pentosin CHF 7.1 or equivalent ATF Dexron II)
Common Failures:
Rust (wheel wells, rocker panels, around windows), vacuum leaks affecting HVAC and engine control, fuel distributor leaks (K-Jetronic), differential mount bushings, heater control valve issues, evaporator core leaks (AC systems).
Diesel Variants Note:
While this manual is for the 280E, common W123 issues include glow plug failures (diesel), injector pump issues, and crankshaft pulley problems.
Manufacturer History:
Mercedes-Benz has a long-standing reputation for engineering excellence, luxury, and durability since its inception in 1926.
W123 Development:
The W123 succeeded the W114/W115 'Stroke Eight' and was designed to be even more robust and durable, embodying Mercedes-Benz's 'built to last' philosophy. It offered a more refined ride and improved safety features compared to its predecessor.
280E Positioning:
The 280E represented the higher end of the W123 lineup, featuring the smooth and powerful M110 2.8L inline-six engine, typically with fuel injection for improved performance and efficiency.
Production Years:
1976-1985
Production Locations:
Various Mercedes-Benz plants globally, including Germany (Sindelfingen, Bremen), South Africa, and others.
Total Production W123:
Over 2.7 million units across all body styles (sedan, coupe, estate, long wheelbase).
