How Do You Change a Differential Seal on a Semi Truck?

Changing a differential seal on a semi truck isn’t an easy task, but it is possible for a determined do-it-yourselfer. Before attempting this repair, make sure you have all the necessary tools and supplies on hand. You will also need to know how the differential works and understand how to properly disassemble and reassemble it.

Step 1:

To begin, you will need to prepare the semi truck for the differential seal replacement process. Start by raising the vehicle off the ground using a jack and jack stands, then remove any components that are blocking access to the differential assembly. This may include exhaust pipes and other components mounted near the differential.

Step 2:

Once you have gained access to the differential assembly, start by draining all of the lubricant from it using a container or drain pan. Then remove any bolts or fasteners that are holding the differential cover in place.

Step 3:

After removing all of the fasteners, carefully remove the cover from the differential assembly. This will expose the old seal, which should be carefully removed with a screwdriver or pry bar.

Once it is removed, clean up any debris or dirt that has accumulated around where it was located.

Step 4:

Next, install your new seal onto the axle shaft with a seal installation tool. Make sure that it is installed correctly and securely before reassembling everything else.

Step 5:

Reinstall all of the components you removed earlier, including any bolts and fasteners that were holding them in place. Then refill your differential assembly with fresh lubricant before putting everything back together.



Changing a differential seal on a semi truck isn’t an easy job, but with careful preparation and attention to detail it can be done successfully. It’s important to understand how your truck’s differentials work so you can complete this repair correctly without damaging any of its components.

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James Gardner