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How to Replace a Pinion Seal Leak

Pinion Seal Leak, Replace Pinion Seal Leak
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Published: 11/01/11

One of the most important parts of your vehicles drive train is the differential assembly which includes a pinion and seal. The pinion connects the rear axle and drive shaft allowing the wheels to spin when the axle gears are turned. The pinion seal keeps fluid in the differential assembly so the wheels can turn properly. Many vehicles develop a leak in the pinion seal over time but this should not be ignored because the gears need to be well lubricated to handle the friction from them turning. It is time to replace your pinion seal if you see fluid leaking from your rear axle, the steering wheel sticks in a certain spot, or if your power steering fluid is low quickly after adding power steering fluid.

Save yourself the hassle of a major repair down the road and use our easy guide on how to replace a differential pinion seal leak.
Before starting the replacement of the differential pinion seal it is important to make sure the bearing is in good condition. To do this rotate and shake the U-joint to ensure the pinion flange, where the U-joint connects to the differential, does not move up and down. If the differential bearing is not moving then proceed with the directions below.

1.    Remove the 4 bolts holding the drive shaft with a wrench
2.    Move the drive shaft forward to free up the pinion flange
3.    Make a note of the pinion flange parts
       a.    Count the number of threads exposed on the end of the pinion gear. You will need to put the nut on the exact same way it is now.
       b.    Mark the location of the pinion flange in relation to the nut and the gear. Make a straight line on these three parts to ensure they are placed in their proper positions again.
4.    Remove the nut and washer
       a.    Use an impact wrench to remove the nut.
       b.    The washer will just slide off once the nut is removed.
5.    Remove the pinion flange
       a.    Use a pinion flange puller and impact wrench on the center bolt of the pinion flange puller.
6.    Remove the pinion seal
       a.    Use a hammer and chisel, seal puller, or screw driver. Be sure not to scratch surrounding parts in the process.
       b.    When the seal is removed more liquid will drain from the pinion and bearing.
       c.    It’s best to raise the back of the vehicle higher than the front because it allows more fluid to drain from the front of the differential.

The leaking pinion seal has now been removed and we are ready to install a new pinion seal. If there is a problem with the differential bearing, additional steps would need to be taken before re-installing the new pinion seal. Be sure to look for these tips on one of our other forum posts.

1.    Clean the differential
       a.    It’s important to clean inside the front of the differential where the pinion seal once was and where the new seal will go.
       b.    Use brake fluid and a clean rag.
2.    Install the new pinion seal
       a.    The inside of the seal can be greased and a strong adhesive can be used on the outside of the seal to provide more protection from leaks.
       b.    Set the seal in the differential and tap in with a hammer until it is flush with the differential.
       c.    Wipe away the excess grease/adhesive from the differential.
3.    Re-install the pinion flange
       a.    A strong adhesive can be used on the inside of the pinion flange.
       b.    Remember to line up the marks made in step 3 and slide onto the differential.
4.    Re-tighten the pinion nut
       a.    This may take some time to line up the marks correctly.
5.    Re-install the drive shaft
       a.    Slide the drive shaft back into the pinion flange.
       b.    Tighten the 4 bolts to connect the drive shaft and pinion flange.
6.    Re-fill the transmission fluid
       a.    Pull the fill plug located on the differential and fill it with synthetic gear oil. This should be filled until it comes out of the fill plug.
       b.    Tighten the fill plug.
7.    Clean the differential
       a.    Remove any power steering fluid, dirt, etc from the differential and drive shaft.
8.    Fill the transmission fluid reservoir
       a.    Put the car back on the ground and fill the vehicle with transmission fluid to the correct level.

We hope you found these DIY tips helpful. Please let us know if you have any questions or car repairs that you would like us to cover in a forum posting. Be sure to watch the additional car maintenance tips that we have covered on our YouTube channel - http://www.youtube.com/user/TheTimkenCompany .
Thanks for visiting Timken Connect.

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