Market Segment:
Mid-size luxury executive car, renowned for build quality, durability, and comfort.
Key Competitors:
BMW 5 Series (E28), Audi 100/200, Volvo 240/700 Series, Jaguar XJ (XJ6 Series III)
Defining Characteristics:
Exceptional build quality, robust engineering, excellent ride comfort, spacious interior, strong safety reputation (for its era), availability of both gasoline and diesel engines.
Intended Users:
Mercedes-Benz W123 owners and enthusiasts seeking to perform their own maintenance, repairs, and diagnostics.
Benefit To Owner:
Empowers owners to save significant money on dealership service costs, gain a deeper understanding of their vehicle, and maintain its longevity and value.
Years Covered:
1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985
Body Styles Covered:
All W123 body styles (Saloon, Estate, Coupé, Long Wheelbase Saloon)
Page Count Estimate:
Varies by specific edition, typically 800-1500+ pages for comprehensive WSMs
Manual Type:
Workshop Service Manual (WSM) / Repair Manual
Digital Delivery:
Instant Download
Print Quality:
Full Printable, High Resolution
Compatibility:
All Versions of Windows & Mac
Software Requirements:
Adobe PDF Reader
Powertrain:
Engine Mechanical, Fuel System (Gasoline & Diesel), Cooling System, Exhaust System
Drivetrain:
Transmission (Manual & Automatic), Clutch, Drive Shafts, Differentials, Axles
Chassis:
Suspension (Front & Rear), Steering System, Brakes (Hydraulic, Parking), Wheels & Tires
Electrical:
Ignition System, Starting System, Charging System, Lighting System, Gauges & Instruments, Wiper/Washer System, Power Windows/Locks, Climate Control (HVAC), Radio/Audio
Body And Trim:
Body Panels, Doors, Hood, Trunk, Bumpers, Glass, Interior Trim, Seats, Convertible Tops (if applicable)
Heating Ventilation Air Conditioning:
HVAC System Components, Refrigerant, Operation, Troubleshooting
Maintenance:
Routine Maintenance, Oil Changes, Filter Replacements, Tune-ups, Fluid Checks & Replacements
Diagnostics And Troubleshooting:
Symptom-based diagnosis, Diagnostic Trouble Codes (DTCs) where applicable (e.g., early EFI systems), Electrical Troubleshooting Charts
Repair And Rebuild:
Engine Overhaul, Transmission Rebuilds, Suspension Component Replacement, Brake System Repair, Electrical Component Repair/Replacement
Adjustment And Calibration:
Carburetor Adjustments, Ignition Timing, Valve Adjustments, Headlight Aiming
Wiring And Schematics:
Comprehensive Electrical Wiring Diagrams for all vehicle systems
Depth Of Coverage:
In-depth, professional-level repair procedures, including detailed component removal, disassembly, inspection, repair, assembly, and installation steps.
Diagnostic Procedures:
Detailed diagnostic trees and fault finding procedures for mechanical, electrical, and fuel system issues.
Special Tools And Equipment:
Identification of specific tools required for various repair and maintenance tasks.
Gasoline Engine Options:
M110 (2.8L Inline-6, DOHC), M123 (2.5L Inline-5, SOHC), M115 (2.0L Inline-4, SOHC), M116 (3.8L V8 - rarely in W123, more in W116/W126)
Diesel Engine Options:
OM615 (2.0L Inline-4 Diesel), OM616 (2.4L Inline-4 Diesel), OM617 (3.0L Inline-5 Diesel, naturally aspirated & turbocharged)
Power Output Range:
Approximately 70 hp (diesel) to 185 hp (2.8L 6-cylinder)
Torque Output Range:
Approximately 97 lb-ft (diesel) to 170 lb-ft (2.8L 6-cylinder)
Fuel Delivery Gasoline:
Carburetor (Zenith, Solex) for most models; Fuel Injection (Bosch K-Jetronic/CIS) for later 2.8L models.
Fuel Delivery Diesel:
Mechanical Injection Pump (Bosch)
Engine Layout:
Inline-4, Inline-5, Inline-6, V8 (rare)
Cooling Type:
Liquid-cooled
Era Specific Safety:
Designed with a focus on structural integrity, crumple zones, and passive safety features, considered very safe for its time.
Braking System:
Front Discs, Rear Drums (standard); Four-Wheel Discs on some higher-performance models.
Steering System:
Recirculating Ball (often with power assist)
Seatbelts:
Standard seatbelts, often with front pre-tensioners on later models.
Driver Visibility:
Excellent all-around visibility due to large glass areas and upright cabin design.
Oil Change Interval:
Typically 7,500 - 10,000 miles (12,000 - 16,000 km) or 12 months, depending on oil type and driving conditions.
Major Service Intervals:
Comprehensive checks and component replacements at 30,000, 60,000, 100,000 miles (50,000, 100,000, 160,000 km) including valve adjustments, fuel filter replacement (diesel), spark plugs, etc.
Engine Oil:
API SG or higher, SAE 10W-40 or 15W-40 recommended (consult manual for specific engine type and climate).
Transmission Fluid Automatic:
MB 236.1 or equivalent (e.g., Dexron III for later versions, but always verify).
Brake Fluid:
DOT 3 or DOT 4.
Coolant:
Ethylene Glycol based coolant with corrosion inhibitors, mixed 50/50 with distilled water.
Common Wear Items:
Vacuum lines (can lead to central locking or climate control issues), Suspension bushings, Ball joints, Flex discs (driveshaft), Heater blower motor, Glow plugs (diesel), Injector pump seals (diesel).
Body Corrosion:
Rust is a common concern, particularly in wheel arches, rocker panels, door bottoms, and around window seals.
Mercedes Benz Legacy:
Continued Mercedes-Benz's reputation for engineering excellence, durability, and safety, building upon the success of the W114/W115 (Stroke 8) models.
W123 Development:
Introduced as a replacement for the W114/W115, featuring more advanced aerodynamics, updated styling, and a wider range of engine options, including the groundbreaking turbocharged diesel.
Production Years:
1976-1985
Production Volume:
Over 2.7 million units produced worldwide.
Manufacturing Locations:
Mainly Germany, with assembly plants also in other countries.
