Mercedes OM617 Engine – Specifications, Variants, and Technical Overview

 

OM617 Engine – General Description

The Mercedes-Benz OM617 is a five-cylinder diesel engine produced from the mid-1970s to the early 1990s. It is widely recognized for its exceptional durability, mechanical simplicity, and long service life. The engine earned a global reputation for reliability in passenger cars, commercial vehicles, and industrial applications.

Its ability to operate for hundreds of thousands of kilometers with minimal maintenance made it a preferred choice for taxi fleets, off-road vehicles, and regions with harsh operating conditions.

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1. Engine Background

The OM617 was developed as an evolution of the OM615 and OM616 diesel engines. Mercedes-Benz designed it to increase power output while maintaining the proven reliability and mechanical simplicity of earlier models.

Production Period: 1974–1991

2. Engine Design Overview

The OM617 is a 3.0-liter, inline five-cylinder diesel engine available in naturally aspirated and turbocharged configurations. The design prioritizes durability, serviceability, and long-term reliability.

2.1 Key Design Features

• Cast-iron cylinder block and cylinder head
• Mechanical inline fuel injection pump
• Gear-driven timing components
• Large oil capacity for improved lubrication
• Low specific power output for extended service life

3. Engine Variants

3.1 OM617 Naturally Aspirated

• Power Output: approx. 80–88 hp
• Applications: W123 series
• Characteristics: simple, long service life

3.2 OM617 Turbocharged (OM617A)

• Power Output: approx. 120–125 hp
• Applications: W126 300SD, W123 Turbo (North America)
• Characteristics: reinforced internals, improved cooling

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4. Technical Specifications

Specification	Value
Engine Type	Inline 5-cylinder diesel
Displacement	3.0 L
Bore × Stroke	90.9 mm × 92.4 mm
Compression Ratio	Approx. 21.5:1
Fuel Injection	Mechanical inline pump
Valvetrain	SOHC, 2 valves per cylinder
Cooling System	Water-cooled
Fuel Type	Diesel

5. Engine Applications

5.1 Passenger Vehicles

• W123 300D / 300CD / 300TD
• W126 300SD

5.2 Off-Road and Utility Vehicles

• G-Class (460 series)
• Military and UN vehicles

5.3 Industrial and Marine Use

• Stationary generators
• Industrial pumps
• Auxiliary power units

6. Reliability Characteristics

6.1 Overbuilt Components

• Thick cylinder walls
• Heavy-duty rotating assembly
• High-strength block design

6.2 Mechanical Fuel System

• No ECU or electronic controls
• High tolerance for poor fuel quality
• Simple field-serviceable components

6.3 Long Service Life

• Typical lifespan: 500,000 km+
• Documented cases exceeding 1,000,000 km

7. Summary

The OM617 engine is recognized for its mechanical simplicity, robust construction, and exceptional service life. Its proven performance in passenger vehicles, off-road platforms, and industrial applications has made it one of the most respected diesel engines produced by Mercedes-Benz.

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