DIY Guide: How to Replace the Timing Belt on Your Subaru EJ25 Engine

If you own a Subaru EJ25 engine, then you already know that it is a reliable and powerful engine. However, even the most durable engines are subject to wear and tear, and one of the most critical components that often needs replacing is the timing belt.

Replacing the timing belt on your Subaru EJ25 engine might seem like a challenging task, but with the right tools and some basic mechanical know-how, you can do it yourself. Not only will you save money by doing it yourself, but you will also feel a sense of accomplishment knowing that you completed this essential task.

Why Should You Replace the Timing Belt on Your Subaru EJ25 Engine

The timing belt is a critical part of your engine’s operation, and when it fails, it can cause severe damage to your engine. The timing belt keeps the engine’s camshaft and crankshaft synchronized and running smoothly. If the timing belt snaps, it can cause the pistons to collide with the valves, causing significant damage to the engine. That’s why it’s essential to replace the timing belt on schedule, usually around every 60,000 miles.

Tools Needed to Replace the Timing Belt on Your Subaru EJ25 Engine

Before you begin the replacement process, you’ll need these tools:

  • Socket Set: You’ll need metric sockets ranging from 8mm to 19mm, including a deep socket.
  • Torque Wrench: You’ll need a torque wrench to tighten the bolts precisely.
  • Timing Belt Tensioner Tool: You will need the proper tool to tighten the timing belt tensioner.
  • Crankshaft Pulley Holder: You’ll need a quality crankshaft pulley holder to keep the pulley from turning.
  • Breaker Bar: You’ll need a breaker bar to help remove the crankshaft pulley bolt.
  • Timing Light: You’ll need a timing light to make sure the timing is set correctly.
  • New Timing Belt and Tensioner: You’ll need to purchase a new timing belt and tensioner kit.
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Step-by-Step Guide for Replacing the Timing Belt on Your Subaru EJ25 Engine

Now that you have all the necessary tools let’s get started on the step-by-step guide.

Step 1: Remove the Negative Battery Cable

Your safety is essential during this process, and the first step is to disconnect the negative battery cable to avoid any electrical accidents.

Step 2: Remove the Engine Covers

Remove the engine covers that conceal the timing belt area.

Step 3: Remove the Drive Belts

You’ll need to remove any drive belts that are obstructing access to the timing belt.

Step 4: Remove the Timing Belt Covers

Remove the timing belt covers to gain access to the timing belt.

Step 5: Remove the Crankshaft Pulley Bolt

Use your breaker bar and crankshaft pulley holder to remove the crankshaft pulley bolt.

Step 6: Remove the Old Timing Belt and Tensioner

Remove the old timing belt and tensioner. You’ll use the timing belt tensioner tool to release the tension on the old belt, then remove it along with the tensioner.

Step 7: Install the New Timing Belt and Tensioner

Install the new timing belt and tensioner by following the manufacturer’s instructions. Use the timing belt tensioner tool to tighten the tensioner correctly.

Step 8: Reinstall the Crankshaft Pulley and Bolt

Reinstall the crankshaft pulley and bolt, making sure to torque the bolt to the precise specifications recommended by Subaru.

Step 9: Check the Timing

Use your timing light to check that the timing is correct. You’ll need to adjust the timing if it’s not set correctly, then re-check with the timing light.

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Step 10: Reinstall Everything in Reverse Order

Reinstall the timing belt covers, drive belts, and engine covers. Finally, reconnect the negative battery cable once you’ve finished.

Tips for Ensuring the Timing is Set Correctly

Here are some essential tips to keep in mind to make sure the timing is set correctly:

  • Take your time, and double-check each step as you go along.
  • Ensure that the crankshaft and camshafts are correctly aligned and that you have no slack on the timing belt.
  • Use a torque wrench to torque all bolts precisely.
  • Always consult your Subaru owner’s manual for specific instructions and torque values.

Common Mistakes to Avoid During the Process

Here are a few common mistakes to avoid when replacing the timing belt:

  • Not using the correct tools: Make sure to purchase the proper tools specifically designed for the Subaru EJ25 engine to ensure you complete this task correctly.
  • Failing to replace the tensioner: Always replace the timing belt tensioner when you replace the timing belt to ensure optimal performance and protection of your engine.
  • Not setting the timing correctly: The timing must be set precisely, or it can cause significant damage to your engine.


Replacing the timing belt on your Subaru EJ25 engine might seem like a daunting task, but with the proper tools and a bit of mechanical know-how, it’s a task that you can do yourself. By following this guide, you can save money and add a valuable skill to your DIY car maintenance repertoire. Remember to check for common mistakes and follow all the steps carefully to ensure your engine continues to run smoothly.

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Peter Banks

With years of experience as a professional mechanic and Subaru specialist, Peter is one of the most respected members of our team. He's written several articles on Subaru maintenance and repair, and his advice and tips are always practical and helpful. When he's not working on cars, he enjoys cooking and trying out new recipes.

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