A pinion seal ensures that oil in the differential doesn't leak out, and water, dirt, or debris don’t get in. If a vehicle is maintained well, the pinion seal will remain in place and perform well. This, in turn, will keep the differential in good shape and allow it to operate optimally.

However, due to reasons like frequent submersion in mud or water and damage from trail debris, the pinion seal may fail. A faulty pinion seal will start leaking, thus causing damage to the differential and other parts like the gear if not fixed. 

Although pinion seal maintenance recommendations vary from one manufacturer to another, one thing remains true to all. It’s always best to replace the pinion seal immediately when there’s a leakage.

Fortunately, replacing a pinion seal isn't an uphill task, and with the right tools, you can do it from your garage. There are different methods to replace the rear pinion seal. In this article, we’ll look at the simple and most commonly used approach.

Materials & Equipment

To replace the pinion seal, you need to remove and install the pinion shaft nut and flange. You’ll need the following: new pinion seal, repair manual, seal puller, wrench set, ratchet, socket set, wheel chocks, breaker bar, drain pan, jack, and hammer. 

Make sure you have all the equipment before you proceed.

Procedure in Replacing the Pinion Seal

1. First, secure the vehicle by parking it on flat ground. Check the vehicle’s wheels and raise the axle such that you’ve enough space to work beneath the car.

2. Once everything is ready, set the parking brakes to stabilize the axle. Secure the driveline using a strap to ensure it doesn’t fall on you once you’ve separated it from the yoke. Next, remove the driveline mounting bolts and separate the driveline.

You have the option to tie it up or remove it entirely from the transmission. If you choose the latter, make sure to drain the fluid using the drain pan.

3. Next, remove the axle flange. You can choose to make outlines of the position of the flange and pinion shaft which will guide you when reinstalling or proceed if you know the exact marks. 

After this, disconnect the mounting nut from the flange. Set the puller until it is secure and then remove the flange slowly.

4. Place the drain pan beneath the seal area before removing the pinion seal to collect the fluid that’ll be draining out. Take the seal off using the seal puller and remove any dirt or grime inside the surface of the pinion seal mounts. 

5. Get the new pinion seal ready for installation. Smear the silicone on the mating surface of the seal and then position it for fitting against the axle housing.

6. One by one, reinstall the components you removed in their order. Start with the axle flange and remember to rub on the silicone to the inside of the flange. You’ll also need to lubricate the surface going into the pinion seal.

7. Use a mallet for seating the flange in such a way that there's enough room for the washer and nut. Once again, apply a thin layer of the silicone on the washer, and then install it and the nut on the pinion tightly. Make sure it is as tight as it was when you were unfastening it.

8. The next step is now to install the driveline and mount it to the flange. Fasten the mounting bolts once the flange is in place. Remember, if you had removed the driveline entirely, you'd first need to insert it to the transmission extension housing.

You're now done with the hardest part. Check the axle fluid and top it up to the required level. Carefully release the jack to lower the vehicle and proceed to release the parking brakes.

Conclusion

It is crucial to replace the pinion seal right after you notice the first signs of a faulty rear pinion seal. It will prevent further damage and save you from incurring expenses on major repairs. 

If you feel that the process is too complicated or you lack the necessary equipment, it is best to leave it to the professionals. Make an appointment at the nearest auto repair shop to get it replaced. 

Most car owners rarely inspect their car’s undercarriage unless a problem arises. To them, it’s a classic case of out-of-sight out-of-mind. Nonetheless, it is good practice to look around for any issues in the undercarriage once in a while. 

If you need to replace parts, don’t let the high cost of car spare parts discourage you. CarPart can help you access high-quality yet cheap auto spares through its free Car Part Finder. Read more about this tool and see how it works by requesting a part today!

By Sam O.