Transfer Case Output Shaft Seal Replacement

Introduction

This tutorial provides step-by-step instructions for replacing the transfer case output shaft seal and the companion flange seal on a 3rd Gen Toyota 4Runner or a 1st Gen Tacoma. Following these instructions will help prevent leaks and ensure the proper functioning of your vehicle's transfer case.

Step 1: Gather Necessary Tools and Parts

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

Parts Needed

• Rear Output Shaft Seal: #90311-41007
• Companion Flange Seal: #90312-23001
• Companion Flange Nut: #90179-22016

Tools Required

• Gear Wrench X-Long Ratcheting Box End Wrench Set
• Camshaft and Crankshaft Tool Kit
• Universal Press/Pull Sleeve Kit
• OTC Long Prybar Set
• Plastic Mallet
• 30mm 1/2" Drive Socket
• Torque Wrench
• Grease

You can find many of these tools on Amazon or other retailers.

Step 2: Prepare the Vehicle

1. Lift the Vehicle: Use a jack to raise the vehicle and secure it with jack stands.
2. Remove the Driveshaft: Unbolt the driveshaft from the transfer case to access the output shaft.
3. Clean the Area: Wipe down the area around the transfer case to prevent dirt from entering during the seal replacement.

Step 3: Remove the Old Seal

1. Locate the Output Shaft Seal: This is typically found at the rear of the transfer case.
2. Use a Prybar: Carefully insert a prybar under the old seal and gently pry it out. Take care not to damage the surrounding area.
3. Inspect the Flange: Once the seal is removed, check the companion flange for any wear or damage.

Step 4: Install the New Rear Output Shaft Seal

1. Prepare the New Seal: Apply a thin layer of grease to the outer edge of the new seal.
2. Align the Seal: Position the new seal in the output shaft housing.
3. Press the Seal In: Use a seal installer tool or a suitable size socket to evenly press the seal into place until it is flush with the housing.

Step 5: Replace the Companion Flange Seal

1. Remove the Companion Flange Nut: Use the appropriate wrench to unscrew the nut holding the companion flange in place.
2. Remove the Flange: Gently pull the flange off the output shaft.
3. Replace the Seal: Follow the same procedure as in Step 4 to install the new companion flange seal.

Step 6: Reassemble the Components

1. Reattach the Companion Flange: Position the flange back onto the output shaft and secure it with the companion flange nut. Torque it to the manufacturer's specifications.
2. Reinstall the Driveshaft: Position the driveshaft back onto the transfer case and bolt it securely.
3. Lower the Vehicle: Carefully remove the jack stands and lower the vehicle.

Conclusion

Replacing the transfer case output shaft seal and the companion flange seal is a manageable task that can prevent costly leaks and ensure your vehicle runs smoothly. Always remember to keep your workspace clean and organized to avoid any contamination. After completing the replacement, check for leaks and ensure everything functions correctly. If you encounter any difficulties, consider consulting a professional mechanic.