🏷️ Basic Information

Make:

Mercedes-Benz

Model:

300 D Turbo

Model Code:

W124 (specific chassis designation for this generation)

Model Variant:

Sedan (likely, but the manual might cover other body styles of the W124 platform)

Engine Code General:

OM603

Production Years Covered:

1986-1987

👋 Introduction

Positioning:

Premium diesel sedan known for durability, comfort, and fuel efficiency, competing with other European luxury brands. The 'Turbo' designation signifies enhanced performance over non-turbocharged diesel variants.

Competitors:

BMW 5 Series Diesel variants, Audi 100/200 Diesel variants (less common).

Durability:

OM603 engine renowned for its robust construction and longevity.

Comfort:

W124 chassis known for its refined ride quality and excellent sound insulation.

Fuel Efficiency:

Excellent fuel economy for its class, especially for highway driving, making it popular for long distances.

Value:

Essential for owners and independent mechanics to maintain and repair this sophisticated vehicle, saving on dealership costs and preserving its legendary reliability.

📋 Manual Details

Primary Coverage:

Comprehensive service and repair for Mercedes-Benz 300 D Turbo (W124 chassis)

Engine Coverage:

3.0L Turbocharged Diesel (OM603 engine)

Transmission Coverage:

Automatic Transmission (likely 722.3 or similar)

Chassis Coverage:

Suspension, Steering, Brakes, Body

Electrical Coverage:

Wiring diagrams, components, diagnostics

Estimated Pages:

Over 1000 pages (typical for comprehensive factory-level manuals)

Type:

Factory Service Manual / Repair Manual

Language:

English

Format:

Digital (likely PDF), potentially printed

📖 Manual Coverage

Engine Management:

Fuel injection system (Bosch VE rotary pump), turbocharger system, glow plug system, engine diagnostics, emissions control

Drivetrain:

Automatic transmission overhaul, differential, drive shafts

Suspension:

Front and rear suspension components, shock absorbers, springs, control arms, ball joints, wheel alignment specifications

Brakes:

Hydraulic system, brake calipers, master cylinder, ABS (if equipped), brake pad replacement, rotor specifications

Steering:

Power steering system, steering gear, tie rods, steering column

Electrical System:

12V electrical system, battery, alternator, starter, lighting, instrumentation, power windows, central locking, HVAC controls, detailed wiring diagrams

Body And Trim:

Body panel repair, door mechanisms, interior trim removal and installation, glass replacement, bumpers

Maintenance:

Scheduled maintenance, oil changes, filter replacements, fluid checks and top-offs, belt inspections and replacement

Troubleshooting:

Diagnostic flowcharts, symptom-based troubleshooting for engine, transmission, and electrical issues

Repair Overhaul:

Engine internal component replacement (pistons, rings, bearings), cylinder head removal and repair, turbocharger rebuild, transmission overhaul, brake component replacement

Diagnostics:

Engine timing, compression testing, fuel pressure testing, electrical system testing using multimeter and oscilloscopes

Depth:

Factory-level, including detailed torque specifications, tolerances, diagnostic procedures, and component removal/installation sequences

Diagnostic Tools:

Mention of specific diagnostic tools or techniques recommended by Mercedes-Benz for the era

📊 Manual Specifications

Digital Format:

PDF (typically searchable and bookmarkable)

Quality:

High-resolution scans of original documentation, ensuring clarity of diagrams and text

Physical Binding:

Not applicable for digital, but original manuals were often bound (e.g., spiral-bound, case-bound)

Physical Paper:

Not applicable for digital, but original manuals used durable paper stock

⚙️ Engine Specifications

Engine Type:

Inline-6 Cylinder, Turbocharged Diesel

Displacement:

2.996 liters (3.0 Liters)

Bore X Stroke:

87.0 mm x 84.0 mm

Compression Ratio:

22.0:1

Fuel Delivery:

Bosch VE Rotary Injection Pump

Valvetrain:

Single Overhead Camshaft (SOHC), 2 valves per cylinder

Horsepower Gross:

Approx. 147 hp (110 kW) at 4600 rpm (Europe/US spec may vary)

Torque Gross:

Approx. 236 lb-ft (320 Nm) at 2400 rpm (Europe/US spec may vary)

Fuel Type:

Diesel Fuel

Intake System:

Turbocharged with intercooler

Cooling Type:

Liquid-Cooled

Oil Capacity:

Approx. 7.5 liters (with filter change)

Oil Type Specification:

MB 228.1 or 228.3 (multi-grade diesel engine oil, e.g., 15W-40 or 10W-40 depending on climate)

🔧 Transmission

Type:

4-Speed Automatic Transmission (e.g., 722.3 series)

Type:

5-Speed Manual Transmission (less common for this specific diesel turbo variant in many markets)

Automatic Features:

Lock-up torque converter, hydraulic control, potentially a sport/economy mode selector.

Automatic Transmission Fluid Type:

MB 236.1 (Dexron II or equivalent recommended for maintenance)

Automatic Transmission Fluid Capacity:

Approx. 8.0 - 9.0 liters (total capacity, varies with torque converter drain)

📐 Dimensions

Length:

Approx. 4740 mm (186.6 inches) for Sedan

Width:

Approx. 1740 mm (68.5 inches)

Height:

Approx. 1430 mm (56.3 inches)

Curb Weight:

Approx. 1500-1600 kg (3300-3500 lbs, depending on equipment)

Gross Vehicle Weight Rating:

Typically around 2000-2100 kg

Wheelbase:

Approx. 2800 mm (110.2 inches)

Wheel Size:

Commonly 14-inch or 15-inch alloy or steel wheels

Tire Size:

e.g., 195/65 R15, 205/60 R15

Bolt Pattern:

5x112

Offset:

ET 37 to ET 49 (typical range)

🛡️ Safety Features

Crash Test Data:

While formal crash test ratings were less standardized in the 1980s, the W124 chassis was designed with significant safety features for its time, including a reinforced safety cell and crumple zones. Specific governmental ratings from this era are rare.

ABS:

Anti-lock Braking System (ABS) was an optional feature on many 300 D Turbo models.

Traction Control:

Traction Control System (ASR) was not commonly available on diesel models of this vintage.

Airbags:

Driver's airbag was an optional feature.

Seatbelts:

Pre-tensioned front seatbelts were standard.

Body Structure:

Integrated safety cage with crumple zones front and rear.

💡 Technology Features

Radio System:

Factory-installed analog radio, often with cassette player. Aftermarket head units were common upgrades.

Speaker System:

Basic speaker setup, often front door and rear parcel shelf speakers.

Cruise Control:

Standard or optional, electro-mechanical cruise control.

Climate Control:

Manual or automatic climate control (Thermatic/Thermotronic) depending on trim level, often vacuum-actuated.

Phone Integration:

None from factory. Aftermarket solutions would be required.

🔧 Maintenance

Oil Change Interval:

Typically every 10,000 km (6,000 miles) or 12 months, whichever comes first. Refer to manual for exact specifications based on driving conditions.

Air Filter Replacement:

Every 20,000 - 40,000 km (12,000 - 24,000 miles) or as needed based on inspection.

Fuel Filter Replacement:

Every 20,000 - 40,000 km (12,000 - 24,000 miles). Crucial for diesel engines to prevent injector issues.

Transmission Fluid Service:

Every 60,000 - 100,000 km (36,000 - 60,000 miles) for automatic transmissions. Check manual for specific recommendations.

Coolant Flush:

Every 2-3 years or as specified by coolant type.

Coolant Type:

MB 325.0 (Ethylene Glycol based, pink or red color, long-life coolant)

Brake Fluid Type:

DOT 3 or DOT 4 (typically)

Power Steering Fluid Type:

MB 236.3 (ATF Dexron II or similar)

Common Wear Items:

Vacuum lines for central locking and climate control, injector seals, glow plugs, suspension bushings, sway bar links, potential oil cooler seal leaks.

Diesel Specific Concerns:

Air in fuel system after filter change, injector pump timing, turbocharger wear, exhaust manifold cracks (less common).

Electrical Issues:

Wire harness degradation (especially insulation), fuse box connections, alternator, starter motor reliability.

📚 Vehicle History

Mercedes Benz Legacy:

Mercedes-Benz has a long-standing reputation for engineering excellence, durability, and safety, particularly with its diesel engines and luxury sedans.

W124 Introduction:

The W124 E-Class was introduced in 1984/1985, replacing the W123. It was a significant step forward in design, aerodynamics, and engineering, setting new standards for the mid-size luxury segment. The 300 D Turbo variant was a key part of the diesel lineup, offering a blend of performance and economy.

Diesel Engine Development:

The OM603 engine was an evolution of Mercedes-Benz's highly successful diesel engines, featuring a turbocharger and intercooler to improve power output and response, making the diesel variant a much more competitive offering in terms of acceleration.

Manufacturing Locations:

Primarily manufactured in Germany.

Production Run:

The W124 platform was produced from 1984 to 1995, with significant facelifts and updates throughout its lifespan. The 300 D Turbo was a prominent model within this range for the specified years.

🏆 Awards & Recognition

Industry Accolades:

The W124 platform as a whole received numerous accolades for its engineering, build quality, and longevity, often cited as one of the best-engineered cars of its era. Specific awards for the 300 D Turbo variant are rare, but the model contributed to the W124's overall reputation.