Positioning:
The Mercedes-Benz W123 series was positioned as a premium, reliable, and durable executive sedan, estate car, and coupe, known for its engineering quality and longevity.
Competitors:
Competed with vehicles like the BMW 5 Series (E12/E28), Audi 100, and Volvo 240 series, often perceived as more luxurious and robust.
Vehicle Highlights:
Exceptional build quality, robust mechanicals, comfortable ride, sophisticated styling, and a reputation for enduring reliability, especially with diesel variants.
Value Proposition:
Essential for owners and independent mechanics seeking accurate, manufacturer-specific repair information, enabling proper maintenance and restoration of these classic vehicles.
Engine:
Detailed diagnostics, overhaul, and repair for all gasoline and diesel engines offered in 1976, including M115, M110, OM615, OM616, OM617.
Fuel System:
Carburetor service (Zenith, Solex) and fuel injection systems (Bosch K-Jetronic for gasoline, mechanical injection for diesel).
Ignition System:
Distributor timing, coil, spark plugs, breaker points (where applicable), electronic ignition systems.
Transmission:
Manual and automatic transmission (4-speed, 5-speed manual, 3-speed automatic) overhaul, service, and adjustments.
Drivetrain:
Clutch, driveshaft, universal joints, differential, axle shafts, wheel bearings.
Suspension:
Front independent suspension (double wishbone), rear independent suspension (multi-link), shock absorbers, springs, anti-roll bars, bushings.
Steering:
Power steering system, steering box, tie rods, steering linkage.
Brakes:
Front disc brakes, rear drum brakes, hydraulic system, brake lines, master cylinder, calipers, wheel cylinders, parking brake.
Electrical System:
Wiring diagrams, starter, alternator, battery, lighting, horn, wipers, heater blower, instrumentation, fuse box.
Body And Chassis:
Body panel removal/installation, door mechanisms, window regulators, locks, interior trim, underbody coating.
Heating And Air Conditioning:
HVAC system service, heater core, blower motor, air conditioning components (if factory-equipped).
Maintenance:
Routine service intervals, fluid changes, filter replacements, lubrication points, belt tensioning.
Troubleshooting:
Diagnostic charts, symptom-based troubleshooting for mechanical and electrical issues.
Repair:
Step-by-step instructions for component removal, disassembly, cleaning, inspection, repair, and reassembly.
Overhaul:
Complete engine, transmission, and differential rebuild procedures.
Adjustments:
Valve adjustments, idle speed, carburetor adjustments, ignition timing, brake adjustments.
Specifications:
Torque specifications for all fasteners, clearances, tolerances, and fluid capacities.
Depth:
Comprehensive, from basic maintenance to complete engine and transmission overhauls, including detailed diagnostic procedures.
Engine Options 1976:
2.5L Inline-4 (M115), 2.8L Inline-6 (M110), 2.4L Diesel Inline-4 (OM615), 3.0L Diesel Inline-5 (OM617).
Horsepower Range:
Approx. 70-130 hp (depending on engine and market).
Torque Range:
Approx. 100-170 lb-ft (depending on engine).
Gasoline Fuel Delivery:
Stromberg or Zenith Carburetors (e.g., 2.5L) or Bosch K-Jetronic Fuel Injection (e.g., 2.8L).
Diesel Fuel Delivery:
Bosch mechanical injection pumps with injectors.
Engine Construction:
Cast iron block, aluminum alloy cylinder head (typically).
Oil Change Interval:
Typically every 5,000-7,500 miles (8,000-12,000 km) or 6-12 months, depending on driving conditions and engine type.
Major Service Intervals:
Spark plugs, fuel filters, air filters, coolant changes at recommended intervals (e.g., 30,000 miles / 48,000 km).
Engine Oil Specification:
API SF or SG classification; viscosity SAE 10W-40 or 15W-40 recommended, depending on climate (consult manual for exact MB specifications).
Coolant Specification:
Ethylene glycol-based antifreeze, typically a 50/50 mix with distilled water. MB Spec 325.0 (or equivalent).
Brake Fluid Specification:
DOT 3 or DOT 4 hydraulic brake fluid.
Common Wear Items:
Bushings (suspension, control arms), fuel lines (rubber degrading), vacuum hoses, idle control valves, exhaust system corrosion, headlight switch issues, RWD driveshaft center support bearing.
Diesel Specific Issues:
Glow plug system reliability, potential for injector pump leaks, valve seat wear on early models.
Gasoline Specific Issues:
Carburetor tuning and wear, K-Jetronic fuel distributor issues, ignition module failures.
Mercedes Benz Legacy:
Mercedes-Benz has a long history of engineering excellence, safety, and durability dating back to the late 19th century.
W123 Introduction:
Introduced in 1976 as the successor to the W114/W115 (Stroke Eight) series. It was a significant evolution in Mercedes-Benz's mid-size lineup.
Body Styles:
Offered as a 4-door Sedan, 5-door Estate (S123), 2-door Coupe (C123), and 4-door Long-wheelbase Sedan (V123).
Production Years:
1976-1985
Manufacturing Locations:
Germany (Sindelfingen, Bremen), South Africa, Argentina, and assembly plants worldwide.
