Years Covered By Manual:
1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985
Chassis Codes:
W116 (1976-1980), W123 (1977-1985)
Engine Codes:
OM617 (Naturally Aspirated and Turbocharged variants)
Original Market:
Luxury/Executive Diesel Sedan (W116), Executive Sedan/Wagon/Coupe (W123). Known for durability, comfort, and fuel efficiency.
Competitors:
BMW 5 Series Diesel, Audi Diesel models, Volvo Diesel models, and other premium European marques of the era.
Brand Heritage:
Mercedes-Benz is synonymous with engineering excellence, safety, and longevity, particularly in its diesel offerings.
Manual Value Proposition:
Provides access to the same diagnostic and repair information used by authorized Mercedes-Benz technicians, empowering owners and independent shops.
Manual Uniqueness:
Covers two distinct chassis generations (W116 and W123) within the 300D model, offering broad applicability for owners of these iconic vehicles.
Regions Covered:
Global (specifications are generally applicable across markets, with notes for regional variations where significant)
Vehicle Types Covered:
Sedan, Coupe, Wagon (for W123 generation); Sedan (for W116 generation)
Estimated Page Count:
Likely 1000+ pages (typical for comprehensive factory service manuals covering multiple model years and variants)
Type:
Factory Service Repair Workshop Manual
Language:
English (primary language for sales description, actual manual may have variations or translations available)
Format:
Digital Download (PDF)
Powertrain:
Engine mechanical, fuel injection (Bosch inline injection pump), cooling system, exhaust system, intake system, engine management (mechanical governor and diesel control)
Drivetrain:
Clutch, manual transmission, automatic transmission (e.g., 4-speed 722.1), driveshafts, differential, axles
Suspension Steering:
Front independent suspension (double wishbone), rear independent suspension (semi-trailing arm), power steering system, steering gear
Brakes:
Front disc brakes, rear drum brakes (or disc depending on specific model variant), hydraulic system, parking brake
Electrical:
Battery, charging system (alternator), starting system, ignition system (glow plugs), lighting, instrumentation, wiring diagrams for all systems
Body Chassis:
Body panels, doors, windows, interior trim, chassis components, rust prevention, body repair procedures
HVAC:
Heating, ventilation, and air conditioning (if equipped) system diagnosis and repair
Maintenance:
Scheduled maintenance intervals, oil changes, filter replacements, fluid checks and top-offs, lubrication points
Troubleshooting:
Diagnostic flowcharts, symptom analysis, common problems and their solutions for all major systems
Repair:
Component removal and installation, detailed disassembly and reassembly instructions, torque specifications for critical fasteners
Diagnostics:
System testing procedures, specifications for testing components (e.g., compression testing, injection timing checks)
Depth:
Comprehensive: Covers everything from basic fluid changes to complete engine overhauls, transmission rebuilds, and electrical system troubleshooting.
Engine Type:
Inline 5-Cylinder Diesel
Displacement Liters:
3.0 L (2998 cc)
Bore X Stroke Mm:
87.0 x 100.0 mm (typical for OM617)
Compression Ratio:
21.0:1 (typical for OM617)
Horsepower Hp Naturally Aspirated:
Approx. 77-80 hp @ 4000-4200 rpm (varies slightly by year and region)
Horsepower Hp Turbocharged:
Approx. 115-125 hp @ 4000-4350 rpm (for OM617.95x Turbo variants)
Torque Lb-Ft Naturally Aspirated:
Approx. 125-130 lb-ft @ 2200-2400 rpm
Torque Lb-Ft Turbocharged:
Approx. 170-185 lb-ft @ 2400-2600 rpm
Injection System:
Bosch Inline Fuel Injection Pump (EP/VE type)
Glow Plugs:
Yes, essential for cold starting diesel engines
Transmission Type Standard:
4-Speed Manual Transmission (common on base models)
Transmission Type Optional:
4-Speed Automatic Transmission (e.g., 722.1 or 722.3)
Automatic Features:
Hydraulic torque converter, often with a vacuum modulator for shift control.
Automatic Transmission Fluid:
MB 236.1 (e.g., Dexron-II or equivalent specification, check manual for exact type and MB approval)
Automatic Transmission Capacity:
Approx. 7-8 liters (check manual for exact capacity)
Crash Test Data Availability:
Limited official crash test data from modern agencies, but renowned for robust chassis and build quality for its era.
Braking System:
Hydraulic disc front, drum rear (often with optional ABS in later years, but uncommon on 300D models).
Steering System:
Power assisted recirculating ball (W116), Power assisted parallelogram steering (W123).
Body Structure:
Reinforced passenger cell, crumple zones (designed according to safety standards of the 1970s/1980s).
Seat Belts:
Three-point front seat belts, two-point rear seat belts (standard).
Headrests:
Front headrests, rear headrests available on some models.
Audio System:
Basic AM/FM radio, often with cassette player. Speaker count typically 4-6.
Navigation:
N/A (Not available in this era)
Cruise Control:
Optional on many models.
Power Features:
Power windows, power door locks, power antenna (often optional or standard on higher trims).
Connectivity Options:
N/A (No integrated smartphone connectivity or Bluetooth)
Oil Change Interval Km:
Every 7,500 - 10,000 km (or as specified in the manual based on driving conditions).
Fuel Filter Replacement Interval Km:
Every 20,000 - 30,000 km, or as needed if experiencing fuel delivery issues.
Air Filter Replacement Interval Km:
Every 15,000 - 25,000 km, or more frequently in dusty conditions.
Transmission Fluid Change Interval Km:
Automatic: Every 40,000 - 60,000 km. Manual: Less frequent, primarily inspect and top-off.
Engine Oil Type:
API CD or CE rated diesel engine oil, viscosity typically 10W-40 or 15W-40 (check manual for exact specifications and ambient temperature suitability).
Engine Oil Capacity Liters:
Approx. 7.5 - 8.0 liters (with filter change, check manual)
Coolant Type:
Ethylene glycol-based antifreeze (e.g., Mercedes-Benz specification 325.0 or 325.2, or equivalent with blue coolant chemistry).
Coolant Capacity Liters:
Approx. 10-12 liters (check manual)
Brake Fluid Type:
DOT 3 or DOT 4 brake fluid (check manual for specific approval)
Common Problems:
Injection pump seals leaking, vacuum leaks, injector pump timing drift, overheating (due to radiator/thermostat issues), vacuum operated accessories failing, early turbocharger failures (on turbo models), valve stem seals drying out, rust in common areas (wheel arches, rocker panels).
Resale Value Impact:
Good maintenance history and the presence of a comprehensive service manual significantly increase resale value and buyer confidence.
Foundation Year:
1926 (merger of Benz & Cie. and Daimler-Motoren-Gesellschaft)
Legacy:
Pioneered diesel technology in passenger cars with the 1936 Mercedes-Benz 260 D.
W116 Introduction:
Introduced in 1972 as the S-Class, the 300SD (turbocharged diesel) was the first diesel S-Class, with the naturally aspirated 300D variant appearing later, typically in global markets.
W123 Introduction:
Introduced in 1976, the W123 became one of Mercedes-Benz's most successful models, offering a robust chassis and a wide range of engines, including the durable OM617 diesel.
Om617 Engine Development:
Evolved from earlier OM615 and OM616 engines, with the OM617 being the first widely produced Mercedes-Benz diesel with 5 cylinders, and later the first turbocharged diesel in a Mercedes passenger car.
Production Period:
W116 300D: Circa 1975-1980. W123 300D: Circa 1976-1985.
Key Markets:
North America (especially for diesel models due to fuel prices), Europe.
