🏷️ Basic Information Identification Make: Mercedes-Benz Model: 300D Chassis Code: W123 Model Years Covered: 1976-1985 Codes Engine Code Primary: OM617 👋 Introduction Market Position Positioning: The definitive guide for owners and independent mechanics seeking to maintain and repair the robust W123 chassis Mercedes-Benz. Competitive Analysis Competitors: While other generic repair guides exist, this manual is specific to the W123 300D, offering Mercedes-Benz specific details. Key Features Value Proposition: Empowers users to perform complex repairs and diagnostics, saving significantly on labor costs associated with dealerships. Depth Of Information: Covers every system in meticulous detail, essential for preserving the longevity of these classic diesel sedans and wagons. 📋 Manual Details Coverage Areas Comprehensive Coverage: Yes Page Count Estimated Pages: 1000+ Manual Type Type: Service & Repair Shop Manual Language Language: English Format Format: Digital Download Compatibility Device Compatibility: PC, MAC, Tablets, Smartphones 📖 Manual Coverage Systems Covered Engine Mechanical: Full overhaul, cylinder head, block, crankshaft, pistons, rings, connecting rods Engine Fuel System: Diesel injection pump (Bosch VE), injectors, fuel lines, filters, glow plug system Cooling System: Radiator, water pump, thermostat, hoses, coolant specifications Lubrication System: Oil pump, oil filter, oil cooler (if applicable), oil change procedures, oil specifications Exhaust System: Manifolds, catalytic converter (later models), mufflers, pipes, mounting Transmission Manual: Clutch, gearbox overhaul, shifting mechanisms, fluid types Transmission Automatic: Service, fluid changes, torque converter, control systems (e.g., K4A/K4C series) Drivetrain: Driveshaft, universal joints, rear axle differential, hub assemblies Suspension Front: Independent suspension, control arms, ball joints, sway bar, shock absorbers, springs Suspension Rear: Semi-trailing arm independent suspension, shock absorbers, springs, alignment Steering System: Power steering system, steering box, tie rods, steering column, wheel alignment Brakes Hydraulic: Master cylinder, brake booster (vacuum assisted), brake lines, fluid specifications Brakes Friction: Front disc brakes, rear drum brakes (most models), caliper/wheel cylinder overhaul, pad/shoe replacement Electrical System: 12V system, battery, alternator, starter motor, ignition system (pre-glow), wiring diagrams Lighting System: Headlights, taillights, interior lighting, fuse box locations and functions Body Exterior: Body panel removal/installation, door mechanisms, window regulators, bumpers, trim Body Interior: Dashboard removal, seat mechanisms, headliner, carpet, sound deadening HVAC System: Heater core, ventilation controls, air conditioning system (if equipped), refrigerant (R12) Procedures Included Routine Maintenance: Oil change, filter replacements (oil, fuel, air), coolant flush, brake fluid flush, lubrication points Engine Repair: Timing chain/belt replacement, head gasket replacement, piston ring installation, valve adjustments Fuel System Repair: Diesel injection pump timing, injector testing and replacement, fuel filter bleeding Transmission Overhaul: Complete disassembly, inspection, and reassembly of manual and automatic gearboxes Brake System Repair: Brake pad/shoe replacement, caliper/wheel cylinder rebuild, bleeding procedure, rotor/drum replacement Electrical Troubleshooting: Wiring diagram interpretation, component testing (alternator, starter, relays), fault diagnosis Suspension Component Replacement: Ball joint, tie rod end, control arm, shock absorber, spring replacement Steering Component Replacement: Steering box overhaul/replacement, tie rod replacement Body Panel Adjustment: Door alignment, hood and trunk adjustments, panel replacement HVAC Component Repair: Heater core replacement, blower motor service, AC system recharge (if equipped) Troubleshooting Guides: Specific symptom-based diagnostic trees for common issues Technical Depth Depth: Professional Level (OEM Equivalent) Diagnostic Capabilities: Advanced diagnostics for engine, transmission, and electrical systems Rebuild Procedures: Detailed instructions for engine, transmission, and differential rebuilds Special Tools: Identification and usage of specialized Mercedes-Benz tools required for certain procedures 📊 Manual Specifications File Format Digital Format: PDF Print Quality Resolution Dpi: High Resolution (300+ DPI) Searchable Text: Yes Printable: Yes Binding Type Digital Binding: N/A (Digital) Paper Type Digital Paper Type: N/A (Digital) ⚙️ Engine Specifications Primary Engine Engine Type: Inline 5-cylinder, Naturally Aspirated Diesel Displacement: 2.998 liters (3.0L) Bore X Stroke: 87.0 mm x 84.0 mm Compression Ratio: 21.0:1 Performance Horsepower Net Est: 72-80 hp @ 4200 rpm (varies slightly by year/market) Torque Net Est: 125-130 lb-ft @ 2400 rpm (varies slightly by year/market) Fuel System Injection System: Bosch VE Rotary Injection Pump Fuel Type: Diesel Fuel (See manual for specific grade recommendations) Lubrication Oil Capacity W Filter: 7.5 Liters (approx. 8 US quarts) Recommended Oil Viscosity: 15W-40 or 10W-40 (refer to manual for seasonal variations and specific MB approvals) 🔧 Transmission Standard Transmission Type: 4-speed Manual (initially), 4-speed Automatic became more common/standard over the years Optional Optional Transmission: 4-speed Automatic (e.g., 4G-Tronic K4A series) Features Automatic Features: Hydraulic torque converter, shift lock (on some models), vacuum modulator for shift control Fluid Specifications Automatic Transmission Fluid: MB 236.3 Specification (e.g., Dexron II or equivalent - consult manual for precise MB approval) 📐 Dimensions Exterior Wheelbase: 2812 mm (110.7 in) Length: 4725 mm (186.0 in) Width: 1785 mm (70.3 in) Height: 1420 mm (55.9 in) Weights Curb Weight Est: 1450 - 1550 kg (3197 - 3417 lbs), varies by body style and equipment Gross Vehicle Weight Rating Gvw: Varies by model, consult vehicle data plate 🛡️ Safety Features Ratings Crash Test Information: Modern crashworthiness standards were evolving; the W123 featured significant passive safety...