Hey guys! Let's dive into the nitty-gritty of the 2007 Subaru Legacy 2.5i engine. If you're a Subaru enthusiast or just looking to learn more about this reliable vehicle, you've come to the right place. We'll cover everything from its specifications to common issues you might encounter. So, buckle up and let's get started!

Overview of the 2007 Subaru Legacy 2.5i Engine

The 2007 Subaru Legacy 2.5i is powered by the EJ253 engine, a 2.5-liter naturally aspirated four-cylinder boxer engine. This engine is part of Subaru's renowned EJ series, known for its durability and distinctive boxer configuration. The boxer engine, also known as a horizontally opposed engine, has pistons that move horizontally, creating a lower center of gravity for the vehicle. This design enhances the car's stability and handling, making it a favorite among driving enthusiasts.

The EJ253 engine features a single overhead camshaft (SOHC) design with four valves per cylinder. It produces around 170 horsepower and 170 lb-ft of torque, providing a good balance of performance and fuel efficiency for daily driving. The engine's design also includes Subaru's Active Valve Control System (AVCS) on the intake valves, which optimizes engine performance across various driving conditions. This system adjusts the intake valve timing to improve low-end torque and high-end power.

Subaru's decision to use the EJ253 in the 2007 Legacy 2.5i was strategic, aiming to provide a reliable and efficient engine that could handle a variety of driving conditions. The engine is known for its longevity, often lasting well over 200,000 miles with proper maintenance. However, like any engine, it has its quirks and potential issues, which we will explore in detail.

The engine's boxer configuration also contributes to its unique sound. Subaru engines have a distinct rumble that many owners find appealing. This sound is a result of the engine's firing order and exhaust system design. While the sound is generally considered a positive attribute, it can sometimes be an indicator of potential exhaust leaks or other issues.

In terms of fuel economy, the 2007 Subaru Legacy 2.5i typically achieves around 20-22 mpg in the city and 27-30 mpg on the highway. These figures can vary based on driving habits, vehicle maintenance, and road conditions. Regular maintenance, such as oil changes, air filter replacements, and spark plug replacements, is crucial for maintaining optimal fuel economy and engine performance.

The EJ253 engine is also relatively easy to work on, making it a favorite among DIY mechanics. Its straightforward design and readily available parts make it accessible for those who prefer to perform their own maintenance and repairs. However, some tasks, such as timing belt replacements, are best left to experienced professionals due to their complexity and the potential for serious engine damage if not done correctly.

Overall, the 2007 Subaru Legacy 2.5i engine is a well-engineered and reliable powerplant that offers a good balance of performance, fuel efficiency, and durability. Its unique boxer configuration and distinctive sound make it a standout engine in the automotive world. However, understanding its potential issues and maintenance requirements is essential for ensuring its longevity and optimal performance.

Key Engine Specifications

When it comes to understanding your 2007 Subaru Legacy 2.5i engine, knowing the specifications is crucial. These specs give you insight into what makes your engine tick and help you diagnose potential problems. Let's break down the key specifications of the EJ253 engine:

• Engine Code: EJ253
• Displacement: 2.5 liters (2457 cc)
• Cylinder Configuration: Horizontally opposed (Boxer)
• Number of Cylinders: 4
• Valvetrain: Single Overhead Camshaft (SOHC), 4 valves per cylinder
• Horsepower: Approximately 170 hp at 6,000 rpm
• Torque: Approximately 170 lb-ft at 4,400 rpm
• Compression Ratio: 10.0:1
• Fuel System: Multi-point fuel injection
• Fuel Type: Regular Unleaded Gasoline
• Bore x Stroke: 99.5 mm x 79 mm
• Firing Order: 1-3-2-4

The compression ratio of 10.0:1 indicates that the engine is designed to efficiently compress the air-fuel mixture, enhancing combustion and power output. This compression ratio also means that the engine is optimized for regular unleaded gasoline, making it economical to run.

The multi-point fuel injection system ensures that fuel is delivered precisely to each cylinder, improving fuel efficiency and reducing emissions. This system is a critical component of the engine's overall performance and reliability.

The bore and stroke measurements (99.5 mm x 79 mm) provide insight into the engine's characteristics. The relatively large bore and short stroke contribute to the engine's ability to rev quickly and produce power at higher RPMs. This design also helps to reduce piston speed, which can improve engine longevity.

The firing order of 1-3-2-4 is specific to the EJ253 engine and is crucial for its smooth operation. This firing order ensures that the engine's cylinders fire in a balanced sequence, minimizing vibrations and maximizing power output. Deviations from this firing order can indicate potential issues with the engine's timing or ignition system.

Understanding these specifications allows you to better appreciate the engineering behind the 2007 Subaru Legacy 2.5i engine. It also helps you to identify potential issues and perform maintenance tasks more effectively. For example, knowing the correct spark plug gap and torque specifications is essential for a successful spark plug replacement.

Furthermore, these specifications are valuable when sourcing replacement parts for your engine. Ensuring that you are using the correct parts is crucial for maintaining the engine's performance and reliability. Using incorrect parts can lead to decreased performance, increased fuel consumption, and even engine damage.

In summary, the key engine specifications of the 2007 Subaru Legacy 2.5i provide a comprehensive overview of its design and capabilities. By understanding these specifications, you can better maintain your engine and ensure its longevity.

Common Problems and Issues

No engine is perfect, and the 2007 Subaru Legacy 2.5i engine is no exception. While the EJ253 engine is generally reliable, it does have some common problems and issues that owners should be aware of. Knowing these issues can help you diagnose problems early and prevent costly repairs. Let's dive into some of the most frequent concerns:

1. Head Gasket Failures: This is perhaps the most well-known issue with the EJ253 engine. The original head gaskets were prone to failure, often leading to coolant leaks and overheating. Symptoms include white smoke from the exhaust, coolant loss, and engine overheating. Replacing the head gaskets with an updated design can mitigate this issue.

2. Oil Leaks: The EJ253 engine is also known for oil leaks, particularly from the valve covers, oil pan, and front crankshaft seal. These leaks can be messy and, if left unattended, can lead to low oil levels and engine damage. Regularly checking for oil leaks and replacing worn seals and gaskets can help prevent this issue.

3. Timing Belt Issues: The timing belt is a critical component of the EJ253 engine, and if it fails, it can cause catastrophic engine damage. Subaru recommends replacing the timing belt every 105,000 miles. Neglecting this maintenance can lead to the timing belt snapping, causing the valves to collide with the pistons. This is a very common and expensive repair.

4. Oxygen Sensor Failures: Oxygen sensors play a crucial role in regulating the engine's air-fuel mixture. Over time, these sensors can become contaminated or fail, leading to poor fuel economy, rough idling, and a check engine light. Replacing the oxygen sensors can restore the engine's performance and fuel efficiency.

5. Catalytic Converter Problems: The catalytic converter is responsible for reducing harmful emissions. Over time, it can become clogged or damaged, leading to decreased engine performance and a check engine light. Replacing the catalytic converter can be an expensive repair, but it is necessary for maintaining emissions compliance.

6. EGR Valve Issues: The Exhaust Gas Recirculation (EGR) valve helps to reduce emissions by recirculating exhaust gases back into the intake manifold. Over time, the EGR valve can become clogged with carbon deposits, leading to rough idling, poor acceleration, and a check engine light. Cleaning or replacing the EGR valve can resolve these issues.

7. Idle Air Control (IAC) Valve Problems: The IAC valve controls the engine's idle speed. If it becomes dirty or malfunctioning, it can cause the engine to idle erratically or stall. Cleaning the IAC valve can often resolve these issues.

8. Knock Sensor Issues: The knock sensor detects engine knocking or pinging. If it fails, it can cause the engine to run poorly and reduce its performance. Replacing the knock sensor can restore the engine's performance and prevent potential damage.

9. Coolant Leaks: Besides head gasket failures, coolant leaks can also occur from the radiator, hoses, and water pump. Regularly checking the coolant level and inspecting the cooling system for leaks can help prevent overheating and engine damage.

10. Spark Plug and Ignition Coil Issues: Worn spark plugs and failing ignition coils can cause misfires, rough idling, and poor acceleration. Replacing the spark plugs and ignition coils can restore the engine's performance and fuel efficiency.

Knowing these common issues can help you stay ahead of potential problems and keep your 2007 Subaru Legacy 2.5i running smoothly. Regular maintenance and timely repairs are essential for preventing these issues and ensuring the longevity of your engine.