Understanding the Challenges: A Deep Dive into the Subaru EE20 Diesel Engine's Block and Crankshaft Issues

The Subaru EE20 diesel engine, a flat-four diesel engine, was first introduced by Subaru in the European market in 2008. This engine is known for its distinctive boxer configuration, where the pistons move horizontally in pairs, a hallmark of Subaru's engineering. Despite its innovative design and initial promise, the EE20 engine has gained a certain notoriety for issues related to block and crankshaft damage. Here's an overview of this engine's characteristics, the problems it faced, and their implications.

Overview of the Subaru EE20 Diesel Engine

Design and Specifications

  • Engine Type: Horizontally opposed (Boxer) 4-cylinder turbo diesel
  • Displacement: 2.0 liters
  • Power Output: Varies by model, approximately 110 kW (147 hp)
  • Torque: Approximately 350 Nm
  • Introduced: 2008, in models like the Subaru Legacy and Outback

Key Features

  • Boxer Layout: Offers a lower center of gravity, contributing to better balance and handling.
  • Turbocharged: Improved efficiency and power output.
  • Common Rail Injection: Provides finer control of fuel injection for efficiency.

Notorious Issues: Block and Crankshaft Damage

Block Damage

  • Cracks and Warping: Some EE20 engines experienced block cracking and warping, often attributed to overheating and stress.
  • Cooling System Design Flaws: Inadequate cooling in certain areas of the engine block was sometimes cited as a contributing factor.
  • Material and Manufacturing Quality: Questions arose regarding the quality and durability of materials used for the engine block.

Crankshaft Damage

  • Bearing Failures: The EE20 was prone to bearing failures, leading to crankshaft damage.
  • Imbalanced Forces: The unique boxer configuration, while advantageous in some respects, also introduced complex vibrational forces that could stress the crankshaft.
  • Maintenance and Operation: Poor maintenance practices and harsh operating conditions were also factors in some cases of crankshaft damage.

Implications and Subaru's Response

Impact on Owners

  • Costly Repairs: Engine block and crankshaft repairs are often expensive, leading to significant costs for owners.
  • Reliability Concerns: These issues have led to a perception of unreliability in what was otherwise a technologically advanced engine.

Subaru's Response

  • Technical Service Bulletins (TSBs) and Recalls: Subaru issued various TSBs and recalls to address specific issues as they became apparent.
  • Warranty Extensions: In some regions, Subaru extended warranties to cover potential engine-related failures.
  • Engineering Revisions: Subaru made engineering changes in subsequent versions of the EE20 to mitigate these problems.


The Subaru EE20 diesel engine, despite its innovative design, faced significant issues with block and crankshaft damage. These problems highlight the challenges inherent in engineering a complex and efficient diesel engine. Subaru's response to these issues, through recalls, warranty extensions, and engineering changes, aimed to address these concerns. However, the legacy of the EE20's problems has impacted the perception of Subaru's diesel engine reliability. As the automotive industry continues to evolve, the lessons learned from the EE20 will undoubtedly influence future engine designs.

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