🏷️ Basic Information

Make:

Mercedes-Benz

Model:

300TD

Year:

1985

Chassis Code:

W123

Engine Code:

OM617.952

👋 Introduction

Vehicle Segment:

Mid-size luxury sedan/wagon, known for robust engineering and durability.

Competitors:

BMW 5 Series (e.g., E28), Audi 100, Volvo 240/740, Cadillac Seville/Brougham.

Diesel Powertrain:

The OM617 turbodiesel engine offered impressive torque and fuel economy for its era, making it a popular choice for long-distance touring and those prioritizing reliability and running costs.

Build Quality:

W123 chassis vehicles are renowned for their over-engineered construction, exceptional longevity, and resistance to rust when properly maintained.

Body Styles:

Available as a sedan, coupe, convertible (230/300CE Cabriolet), and the highly practical station wagon (T-model).

📋 Manual Details

Languages:

English

Regions Covered:

Global (North America, Europe, etc.)

Estimated Pages:

Approximately 700-900 pages (typical for this era's comprehensive manuals)

Type:

Service and Repair Manual

Digital Format:

Downloadable PDF

📖 Manual Coverage

Engine:

Detailed breakdown of the OM617.952 3.0L inline-5 cylinder turbocharged diesel engine, including fuel injection system, cooling, lubrication, and emissions.

Transmission:

Coverage for both the 4-speed automatic and 4-speed manual transmissions, including hydraulic systems, clutch operation, and gear shifting mechanisms.

Drivetrain:

Front suspension, rear axle assembly, differential, driveshafts, and wheel bearings.

Brakes:

Hydraulic brake system, including front disc brakes, rear drum brakes, parking brake, master cylinder, and power brake booster.

Steering:

Recirculating ball steering system, power steering pump, steering gear, and linkage.

Electrical:

Complete wiring diagrams, battery, alternator, starter, lighting system, ignition system (glow plug system for diesel), instruments, and auxiliary components.

Body:

Body panel removal and installation, door mechanisms, glass, upholstery, and structural components.

Climate Control:

HVAC system, including heater core, ventilation, and air conditioning (if equipped).

Maintenance:

Oil changes, filter replacements, fluid checks and top-offs, lubrication points, and general inspection procedures.

Engine Repair:

Engine removal and installation, cylinder head overhaul, piston and ring replacement, camshaft and valve train service.

Transmission Service:

Transmission fluid and filter changes, seal replacements, torque converter service, and manual transmission rebuilds.

Brake Repair:

Brake pad/shoe replacement, rotor/drum machining or replacement, caliper/wheel cylinder rebuilding, bleeding the brake system.

Suspension Steering Repair:

Shock absorber replacement, ball joint service, tie rod end replacement, steering box adjustment.

Electrical Diagnostics:

Troubleshooting electrical circuits, component testing, starter and alternator diagnosis, glow plug circuit testing.

Fuel System Service:

Diesel injection pump calibration, injector testing and replacement, fuel filter replacement, bleeding the fuel system.

Troubleshooting:

Diagnostic procedures for common problems, symptom-based troubleshooting charts.

Depth:

Comprehensive, suitable for professional mechanics and advanced DIY enthusiasts. Covers everything from routine maintenance to complete engine and transmission rebuilds, including diagnostic procedures and specifications.

📊 Manual Specifications

Format:

PDF (Portable Document Format)

Searchability:

Likely text-searchable PDF for easy information retrieval.

Resolution:

High resolution, suitable for printing individual pages or sections.

Binding:

N/A (Digital Format)

Paper Type:

N/A (Digital Format)

⚙️ Engine Specifications

Engine Type:

Inline 5-cylinder, naturally aspirated or turbocharged diesel

Displacement:

3.0 Liters (2998 cc)

Bore X Stroke:

87.0 mm x 88.0 mm

Compression Ratio:

21.0:1 (Typical for OM617.952)

Fuel Delivery:

Bosch inline mechanical fuel injection pump

Horsepower:

Approximately 88 hp (DIN) @ 4000 rpm (for naturally aspirated) / Approximately 125 hp (DIN) @ 4350 rpm (for turbocharged 300TD)

Torque:

Approximately 170 Nm (125 lb-ft) @ 2400 rpm (for naturally aspirated) / Approximately 250 Nm (184 lb-ft) @ 2400 rpm (for turbocharged 300TD)

Fuel Type:

Diesel

Fuel Capacity:

Approximately 70 liters (18.5 US gallons)

Oil Capacity:

Approximately 8.0 liters (8.5 US quarts) with filter change

Coolant Capacity:

Approximately 10.0 liters (10.6 US quarts)

🔧 Transmission

Transmission Type:

4-speed automatic (722.3) or 4-speed manual

Optional Transmission:

5-speed manual transmission became available on later W123 models, but 4-speed was common for 1985 300TD.

Automatic Features:

Hydraulic torque converter, planetary gear sets, governed by vacuum modulation and throttle pressure.

Manual Features:

Traditional clutch and gearshift mechanism.

Automatic Transmission Fluid:

MB 236.1 specification (e.g., Dexron II compatible)

Manual Transmission Fluid:

API GL-4, SAE 80W/90 gear oil

📐 Dimensions

Length:

Approximately 4725 mm (186.0 in) for Sedan

Width:

Approximately 1788 mm (70.4 in) for Sedan

Height:

Approximately 1425 mm (56.1 in) for Sedan

Wheelbase:

Approximately 2795 mm (110.0 in) for Sedan

Curb Weight:

Approximately 1500-1600 kg (3300-3530 lbs) depending on body style and options.

🛡️ Safety Features

Crash Test Information:

No formal crash test ratings (like NHTSA/Euro NCAP) were consistently applied in the same way as modern vehicles. However, the W123 chassis was known for its robust safety cage and crumple zones for its time.

Braking System:

Power-assisted hydraulic brakes, typically with front discs and rear drums. ABS was not standard on most models of this era.

Seatbelts:

Standard 3-point seatbelts for front occupants, lap belts for rear.

Steering Column:

Collapsible steering column designed to absorb impact energy.

💡 Technology Features

Audio System:

Typically featured analog radios, often with cassette players. Upgrades to modern head units are common for enthusiasts.

Cruise Control:

Optional on some models.

Connectivity Features:

None in the modern sense. Features were mechanical or analog electrical.

🔧 Maintenance

Oil Change Interval:

Every 10,000 km (6,000 miles) or 12 months, whichever comes first.

Air Filter Replacement:

Every 20,000 km (12,000 miles) or as needed based on driving conditions.

Fuel Filter Replacement:

Every 20,000 km (12,000 miles) or annually.

Coolant Flush:

Every 2 years or 40,000 km (24,000 miles).

Transmission Service Interval:

Automatic: Every 40,000 km (24,000 miles) for fluid and filter change. Manual: Inspect fluid levels annually.

Engine Oil:

API CD or higher, SAE 15W-40 or 20W-40 diesel engine oil recommended. Check manual for specific viscosity based on climate.

Coolant:

Ethylene glycol based antifreeze, mixed 50/50 with distilled water. MB Specification 325.0 or equivalent.

Diesel Specific:

Glow plug system reliability, injector pump seals, and fuel injector tip wear can occur with high mileage. Also, early signs of turbocharger wear on heavily used vehicles.

Body Rust:

Despite Mercedes' robust rustproofing for the era, common areas for rust include wheel arches, rocker panels, under the battery tray, and around window seals.

Suspension Wear:

Worn control arm bushings, ball joints, and tie rod ends are common due to age and mileage.

Electrical Issues:

Corroded grounds, failing vacuum lines for central locking and self-leveling suspension (if equipped), and aging wiring harnesses can cause intermittent problems.

Oil Filter Example:

Mann Filter W114/1, Mahle KL117/3, or Mercedes-Benz OEM 001 180 1209 (ensure exact part number for specific vehicle)

Air Filter Example:

Mann Filter C2423, Mahle LX46, or Mercedes-Benz OEM 115 090 01 56 (ensure exact part number for specific vehicle)

Fuel Filter Example:

Mann Filter WK80, Mahle KL113, or Mercedes-Benz OEM 000 090 13 51 (ensure exact part number for specific vehicle)

📚 Vehicle History

Mercedes Benz History:

Founded in 1926, Mercedes-Benz has a long-standing reputation for engineering excellence, luxury, and pioneering automotive technologies.

W123 Generation:

The W123 chassis was produced from 1976 to 1985. It succeeded the W114/W115 'Stroke 8' models and was known for its durability, comfort, and significant improvements in safety and engineering.

Diesel Engines Importance:

The OM617 engine, in naturally aspirated and turbocharged forms, became iconic for its reliability and longevity, with many vehicles exceeding 500,000 miles with proper care. The 300TD specifically refers to the turbodiesel wagon variant.

Production Period:

1976-1985

Manufacturing Locations:

Primarily Germany, with some assembly in other countries.

🏆 Awards & Recognition

Reputation:

The W123 series is widely regarded as one of the most reliable and durable Mercedes-Benz models ever produced, earning it a cult following among classic car enthusiasts and those seeking dependable transportation.