Toyota Pinion Seal/Differential Pinion Seal

The differential takes the power from the drive shaft and sends it to the axles to power the wheels. The pinion seal is an oil seal at the point where the power enters the differential.

Obviously, if it’s leaking significantly, you run the risk of ruining your differential gears and bearings if it runs low on oil. However, even with slow leaks there is good reason to repair it.

Often, oil leaks are a result of seals that have gotten hard with age. These hardened seals tend to wear a groove into the sealing surface, which increases the likelihood that the metal sealing surface will need to be repaired or replaced as well.