🏷️ Basic Information Identification Make: Mercedes-Benz Model: 300D Year: 1981 Codes Chassis Code: W123 👋 Introduction Market Position Vehicle Segment: Mid-size Luxury Sedan/Coupe/Wagon Target Audience: Discerning buyers prioritizing build quality, durability, and diesel efficiency over outright performance Competitive Analysis Primary Competitors: BMW 5 Series (e.g., E12/E28), Audi 5+5, Volvo 240/740, American luxury sedans (Cadillac DeVille, Lincoln Continental - though less direct competitors) Key Features Drivetrain: Rear-wheel drive Engine Emphasis: Torquey, durable, fuel-efficient naturally aspirated diesel engine Build Quality: Renowned Mercedes-Benz engineering and construction typical of the era Interior Comfort: Comfortable seating, logical ergonomics, and high-quality materials 📋 Manual Details Coverage Areas Models Covered: All 1981 Mercedes-Benz 300D models Engine Variants Covered: OM617.930 (3.0L Diesel) Transmission Types Covered: 4-speed Automatic, 5-speed Manual (if applicable to specific 1981 models) Page Count Estimated Page Count: Estimated 500-700 pages (typical for comprehensive workshop manuals of this era) Manual Type Manual Type: Workshop Repair Service Manual Language Language: English Format Format: PDF Download Manual Specifications File Format: PDF Print Quality: High-resolution, scannable from original source material Binding Type: N/A (Digital Download) Paper Type: N/A (Digital Download) 📖 Manual Coverage Systems Covered Engine Systems: Diesel injection system (Bosch VE rotary pump), cylinder head, block, pistons, crankshaft, camshaft, timing, cooling, lubrication, exhaust, starting system (starter motor, glow plugs), pre-heating system Transmission Systems: Automatic transmission (e.g., 722.1), manual transmission (e.g., G3/27), clutch, drive shafts, differential, axles Brake Systems: Hydraulic system, disc brakes (front and rear), drum brakes (rear), parking brake, brake fluid specifications, bleeding procedures Electrical Systems: Battery, charging system (alternator), ignition system (though diesel, includes glow plug control), lighting (headlights, taillights, interior), instrumentation, wiring diagrams, fuses, relays, starter, horn Suspension Steering: Front suspension (independent, double wishbone), rear suspension (independent, semi-trailing arm), shock absorbers, springs, ball joints, tie rods, steering gearbox, power steering system Body Chassis: Body panels, doors, hood, trunk, interior trim, glass, seals, chassis lubrication points, frame structure HVAC Systems: Heating, Ventilation, Air Conditioning (if equipped) - blower motor, heater core, refrigerant system (if applicable) Fuel Systems: Fuel tank, fuel lines, fuel filter, diesel injection pump, injectors Procedures Included Maintenance Procedures: Oil change, filter replacement (oil, fuel, air), coolant flush, transmission fluid change, brake fluid flush, differential fluid change, lubrication points, belt inspection/replacement, tire rotation Troubleshooting Diagnostics: Engine starting problems, performance issues, drivability concerns, electrical faults, brake system issues, cooling system leaks, transmission shifting problems Repair Procedures: Engine rebuild (top end, bottom end), transmission overhaul, brake caliper/wheel cylinder replacement, suspension component replacement (ball joints, tie rods), steering gear repair, electrical component replacement, body panel repair Adjustment Procedures: Valve lash adjustment, injection pump timing, idle speed adjustment, brake adjustment (if applicable) Special Tool Requirements: Identification of necessary Mercedes-Benz specialty tools for various procedures Technical Depth Diagnostic Capabilities: In-depth diagnostic trees and flowcharts for common and uncommon issues Rebuild Procedures: Detailed, step-by-step instructions for complete engine and transmission overhauls Specification Accuracy: Precise torque specifications, clearances, fluid capacities, and measurement tolerances Wiring Diagrams: Comprehensive and clearly labeled electrical wiring diagrams for all vehicle systems ⚙️ Engine Specifications Primary Engine Engine Code: OM617.930 Engine Type: Inline-5 Cylinder, Naturally Aspirated Diesel Displacement: 3.0 Liters (2998 cc) Performance Horsepower: Approx. 77-83 hp @ 4000 rpm (depending on specific market tuning) Torque: Approx. 125-130 lb-ft @ 2400 rpm (depending on specific market tuning) Fuel System Injection System: Bosch Inline Mechanical Fuel Injection Pump (VE Type) Fuel Type: Diesel Fuel Cooling System Cooling Medium: Glycol/Water Mixture Lubrication Oil Type Specification: API CD or higher diesel engine oil, SAE 15W-40 or 10W-30 (refer to manual for exact ambient temp recommendations) Oil Capacity: Approx. 6.5 Liters (with filter) 🔧 Transmission Standard Transmission Type: 4-speed Automatic (722.1) Optional Transmission Type: 5-speed Manual (G3/27) Features Automatic Transmission Features: Hydraulically controlled, torque converter, distinct 'kick-down' functionality Fluid Specification Automatic Transmission Fluid Type: MB 236.1 (Dexron II compatible, check manual for precise specification) Fluid Capacity Automatic Transmission Fluid Capacity: Approx. 8-9 Liters (total capacity, fluid change likely 4-5 Liters) 📐 Dimensions Exterior Wheelbase: Approx. 2794 mm (110 in) Length: Approx. 4725 mm (186 in) Width: Approx. 1780 mm (70 in) Height: Approx. 1420 mm (56 in) Weights Curb Weight: Approx. 1450-1550 kg (3200-3400 lbs) depending on body style and equipment Gross Vehicle Weight Rating: Approx. 2000-2100 kg (4400-4600 lbs) Cargo Trunk Capacity: Generous for its class, suitable for luggage and everyday needs 🛡️ Safety Features Ratings Crash Test Results: No formal crash test ratings as per modern standards from the era, but known for robust construction. Active Features Braking System: Four-wheel disc brakes (standard on most W123 models by 1981), power assisted. Steering: Recirculating ball steering, power assisted. Passive Features Body Construction: Reinforced passenger cell, crumple zones. Seat Belts: Three-point inertia reel seatbelts in the front, lap belts in the rear (standard) Headrests: Front headrests standard. 💡 Technology Features Infotainment Audio System: Factory-installed AM/FM radio, often with a cassette player....