How To Change A Subaru DOHC EJ20 EJ25 Timing Belt

Introduction

This tutorial provides a comprehensive guide on changing the timing belt on Subaru DOHC EJ20 and EJ25 engines, commonly found in models such as the Impreza, WRX, STI, RS, Legacy, and Forrester. You'll learn the necessary steps to replace the timing belt, align the components correctly, and also change the water pump, ensuring your engine operates smoothly.

Step 1: Gather Necessary Tools and Parts

Before starting, ensure you have all the required tools and components:

• Timing belt kit (including the timing belt, tensioner, and idler pulleys)
• Water pump (if replacing)
• Socket set
• Wrenches
• Screwdrivers
• Torque wrench
• Timing belt alignment tool (optional)
• Oil and coolant for refilling

Step 2: Prepare the Engine

• Disconnect the battery to prevent electrical issues.
• Drain the engine coolant and oil to avoid spills.

Step 3: Remove Necessary Components

• Remove the front engine cover by unscrewing the bolts.
• Take off the accessory belts connected to the alternator and power steering.
• Remove the crankshaft pulley. You may need a puller for this.
• Detach the timing belt cover by unscrewing and lifting it off.

Step 4: Align the Timing Marks

• Rotate the crankshaft using a socket on the crankshaft bolt until the timing marks on the cam gears and crankshaft align.
• Verify that the marks are correctly positioned for accurate installation of the new timing belt.

Step 5: Remove the Old Timing Belt

• Loosen the tensioner bolt and remove the tension on the old timing belt.
• Carefully remove the old belt from the cam gears and crankshaft.

Step 6: Install the New Timing Belt

• Place the new timing belt around the crankshaft and cam gears, ensuring it follows the correct path.
• Adjust the tensioner and apply tension to the belt according to the manufacturer's specifications.
• Double-check the alignment marks to ensure they remain aligned.

Step 7: Replace the Water Pump (Optional)

If you are replacing the water pump:

• Remove the old water pump from the engine block by unscrewing it.
• Clean the mounting surface and install the new water pump with a new gasket.
• Reattach any hoses or connectors removed during the process.

Step 8: Reassemble the Engine

• Reattach the timing cover and secure it with bolts.
• Reinstall the crankshaft pulley and torque it to the specified settings.
• Put back the accessory belts and tighten them properly.
• Refill the engine oil and coolant.

Conclusion

You have successfully changed the timing belt and, if applicable, the water pump on your Subaru DOHC EJ20 or EJ25 engine. Make sure to double-check all connections and ensure proper fluid levels before starting the engine. Regular maintenance like this can enhance your vehicle's performance and longevity. If you have any questions or need further guidance, refer to your vehicle's service manual.