🏷️ Basic Information

Make:

Mercedes-Benz

Model:

300 D Turbo

Model Codes:

W123 chassis (specific body styles not detailed in product info, but typically Sedan, Wagon, Coupe, Cabriolet)

Engine Codes:

OM615, OM616, OM617 (Note: Product info mentions 615, 617, 110 M115. OM615 and OM617 are diesel engines. M115 is a gasoline engine. The manual title specifies '300 D Turbo', strongly implying diesel. It's possible the manual covers related gasoline variants or has broader engine family coverage.)

Engine Designation:

OM617 (for 300 D Turbo)

👋 Introduction

Target Audience:

Home mechanics, professional technicians, owners of classic Mercedes-Benz vehicles seeking to maintain or repair their vehicles.

Value Proposition:

Provides essential technical information to accurately diagnose, maintain, and repair Mercedes-Benz W123 models, saving on labor costs and ensuring proper vehicle function.

Alternative Resources:

Haynes, Chilton, factory service bulletins, online forums. This manual likely offers a higher level of detail than consumer-oriented manuals and is more specific than general automotive repair books.

Scope Of Coverage:

Extensive coverage of diesel engines (OM617), with potential inclusion of related gasoline engines (OM615, M115), covering mechanical, electrical, and chassis systems.

📋 Manual Details

Manual Type:

Service and Repair Manual

Language:

English (assumed based on product description's common usage)

Format:

Digital (likely PDF, common for online sales)

Page Count:

Not specified in product information. Typical comprehensive service manuals for this era can range from 500-1500+ pages.

📖 Manual Coverage

Engine Mechanical:

Detailed engine overhaul, component identification, fuel injection system, cooling system, lubrication system, engine management (diesel).

Engine Electrical:

Ignition system (for M115, if covered), starter system, charging system, glow plug system (for diesel).

Transmission:

Manual and automatic transmission overhaul, clutch system, torque converter, gear shift mechanisms, fluid specifications.

Drivetrain:

Driveshaft, differential, rear axle assembly, wheel bearings.

Suspension:

Front and rear suspension components, springs, shock absorbers, control arms, bushings, alignment specifications.

Steering:

Steering gear, power steering system, tie rods, steering column, steering wheel.

Brakes:

Hydraulic system, brake calipers, master cylinder, wheel cylinders, brake lines, parking brake, ABS (if equipped on later models within scope).

Fuel System:

Fuel tank, fuel lines, fuel filter, injection pump (diesel), injectors (diesel).

Exhaust System:

Exhaust manifolds, catalytic converter (if applicable), mufflers, exhaust pipes.

Cooling System:

Radiator, water pump, thermostat, coolant hoses, fan.

Electrical System:

Battery, alternator, starter motor, wiring diagrams, fuse box, lighting system, relays, switches.

Body And Interior:

Body panel removal and installation, door mechanisms, window regulators, seat removal, dashboard components.

HVAC:

Heating, ventilation, and air conditioning system service (if equipped).

Routine Maintenance:

Oil changes, filter replacements, fluid checks and top-offs, belt adjustments, spark plug replacement (for gasoline), glow plug checks (for diesel).

Troubleshooting:

Diagnostic procedures for common faults, symptom-based troubleshooting guides.

Component Overhaul:

Detailed step-by-step instructions for rebuilding major components like engines, transmissions, differentials, brake calipers.

Electrical Diagnostics:

Use of multimeters, testing circuits, diagnosing electrical faults, interpreting wiring diagrams.

Tune Up Procedures:

Valve adjustments, timing checks, fuel system adjustments.

Safety Systems Service:

Brake bleeding, parking brake adjustments, power steering system bleeding.

Depth Of Information:

Comprehensive. Covers everything from basic maintenance to complete engine and transmission rebuilds, including torque specifications, clearances, and diagnostic procedures.

Diagnostic Tools:

Details on necessary tools and equipment for repairs, including specialized Mercedes-Benz tools.

Wiring Diagrams:

Includes detailed electrical wiring diagrams for various systems.

📊 Manual Specifications

Digital Format:

PDF (presumed). Searchable text is highly probable for quality manuals.

Image Clarity:

Expected to be high-resolution scans of original factory manuals or well-produced digital versions, suitable for viewing diagrams and photos.

Physical Binding:

Not Applicable (as it's a digital product). If a printed version were sold, it would likely be spiral-bound or case-bound for ease of use in a workshop.

Physical Paper:

Not Applicable (as it's a digital product). Original manuals often used durable paper stock.

⚙️ Engine Specifications

Engine Type:

Inline-5 Cylinder Diesel (OM617)

Engine Displacement:

3.0 Liters (2998 cc)

Aspiration:

Turbocharged

Horsepower Typical:

Approx. 94-125 hp (depending on specific turbo setup and year)

Torque Typical:

Approx. 150-185 lb-ft (depending on specific turbo setup and year)

Acceleration 0 60:

Highly variable, typically 12-16 seconds for the 300D Turbo Sedan.

Fuel Delivery:

Bosch inline injection pump (mechanical) with vacuum-actuated turbocharger control.

Fuel Type:

Diesel

Om615 Variants:

Inline-4 Diesel, typically 2.0L or 2.2L (non-turbo). OM615.913, OM615.940.

Om616 Variants:

Inline-4 Diesel, typically 2.4L (non-turbo). OM616.912, OM616.913.

Om617 Variants:

Inline-5 Diesel, 3.0L. OM617.912 (non-turbo), OM617.952 (turbo).

M115 Variants:

Inline-4 Gasoline, typically 2.0L or 2.2L. M115.912, M115.913, M115.952.

🔧 Transmission

Transmission Type:

4-speed manual (standard on many models, especially earlier ones)

Transmission Type:

4-speed automatic (4G-TRONIC 722.1 or 722.3)

Clutch Type:

Dry single-plate clutch (manual transmission)

Automatic Transmission Features:

Hydraulic torque converter, planetary gear sets, hydraulic control unit.

Automatic Transmission Fluid:

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

Manual Transmission Fluid:

GL-4 rated gear oil, SAE 75W-90 or 80W-90

📐 Dimensions

Model Variants:

Sedan (W123.0xx), Coupe (C123.0xx), Wagon (S123.0xx), Cabriolet (A123.0xx - rare).

Wheelbase Sedan:

Approx. 2795 mm (110.0 inches)

Overall Length Sedan:

Approx. 4725 mm (186.0 inches)

Overall Width Sedan:

Approx. 1790 mm (70.5 inches)

Overall Height Sedan:

Approx. 1440 mm (56.7 inches)

Curb Weight 300D Turbo Sedan:

Approx. 1450-1550 kg (3200-3400 lbs), varies by equipment.

Gross Vehicle Weight Rating:

Typically around 2000-2100 kg (4400-4600 lbs).

Towing Capacity:

Not typically advertised by Mercedes-Benz for this model, but generally limited for heavy loads.

🛡️ Safety Features

Crash Test Results:

No formal NHTSA/IIHS ratings from the era. However, Mercedes-Benz was known for robust build quality and safety features for its time, including crumple zones.

Braking System:

Front disc brakes, rear drum brakes. Typically unassisted or with power assist (vacuum booster).

Steering System:

Recirculating ball steering, often with power assist (e.g., ZF or Bosch system).

Seat Belts:

Front 3-point seat belts, rear lap belts. Some later models may have had 3-point rear belts.

Body Structure:

Reinforced passenger cell, side impact beams (in later iterations), energy-absorbing steering column.

Lighting:

Halogen headlights (common for the era), reliable electrical system for lighting functionality.

💡 Technology Features

Audio System:

Factory AM/FM radio or cassette player. Often single-DIN units. Manual may cover removal/installation and basic troubleshooting.

Cruise Control:

Often a vacuum-operated or electronic cruise control system was available. Manual details its operation and troubleshooting.

Original Features:

Focus is on mechanical and electrical systems, not modern connectivity features like Bluetooth or USB.

🔧 Maintenance

Oil Change Interval:

Typically every 3,000-5,000 miles (5,000-8,000 km) or 6-12 months, depending on driving conditions and oil type used. Manual will specify exact interval and oil viscosity.

Fuel Filter Replacement:

Recommended every 15,000-30,000 miles (24,000-48,000 km) or as per manual recommendations.

Air Filter Replacement:

Inspect every oil change, replace as needed, typically every 15,000-30,000 miles (24,000-48,000 km).

Transmission Fluid Change:

Automatic: 30,000-60,000 miles (50,000-100,000 km). Manual: Check for leaks, fluid change generally not scheduled unless for service.

Coolant Flush:

Every 2-3 years or 30,000-50,000 miles (50,000-80,000 km).

Valve Adjustment:

Diesel engines typically do not require regular valve adjustments, but gasoline engines (M115) do. Manual will provide procedure and interval.

Engine Oil:

API CD or CE classification diesel oil (e.g., 15W-40 or 10W-40 depending on climate). Manual will specify precise viscosity and API rating.

Coolant:

Ethylene Glycol based antifreeze (50/50 mix with distilled water). Mercedes-specific coolant may be recommended.

Brake Fluid:

DOT 3 or DOT 4 hydraulic brake fluid.

Power Steering Fluid:

ATF fluid meeting MB 236.3 specification, or a Dexron compatible fluid.

Diesel Injection Pump:

Vacuum diaphragm failure in the injection pump can cause performance issues or leaks. Manual covers repair/replacement.

Heater Control Valve:

Common failure point causing no heat or stuck heat. Manual details diagnosis and replacement.

Climate Control Actuators:

Vacuum operated actuators for air vents can degrade, leading to incorrect air distribution. Manual shows how to test and replace.

Rust Corrosion:

Common on older vehicles, especially in areas exposed to salt. Manual may cover body repair basics.

Oil Leaks:

Can occur from valve cover gaskets, oil pan gaskets, or crankshaft seals. Manual provides torque specs and gasket replacement procedures.

📚 Vehicle History

Manufacturer Legacy:

Mercedes-Benz has a long history dating back to the invention of the automobile, renowned for engineering excellence, durability, and luxury.

W123 Generation:

The W123 (and its variants) was produced from 1976 to 1985. It succeeded the W114/W115 and was replaced by the W124. It established Mercedes-Benz's reputation for robust, reliable diesel engines and excellent build quality, becoming a benchmark for mid-size luxury sedans.

300D Turbo Introduction:

The turbocharged version of the OM617 engine was introduced to offer improved performance while retaining the diesel's fuel efficiency and durability. This made the 300D Turbo a popular model, especially in markets where fuel economy was a priority.

Production Years:

1976-1985 (for the W123 chassis). The 300D Turbo variant was available within this period.

Manufacturing Locations:

Primarily Germany, with some assembly in other international locations.

Sales Figures Significance:

The W123 series was a major sales success for Mercedes-Benz, with over 2.7 million units produced across all body styles, highlighting its market appeal.

🏆 Awards & Recognition

Industry Reputation:

The W123 series, particularly the diesel variants like the 300D Turbo, is widely recognized for its exceptional durability, reliability, and build quality. Often cited as one of the most over-engineered and longest-lasting Mercedes-Benz models.

Longevity Awards:

Frequently appears on lists of 'Cars Built to Last' or 'Most Reliable Cars of All Time' by automotive publications.

Dealer Service Information:

The manual is derived from or is equivalent to the information used by authorized Mercedes-Benz service centers during the vehicle's production and service life.