To maneuver your car, the steering wheel connects to a steering shaft, which runs through the dash and then down to the gearbox where it also joins the power steering system. Because the power steering system in most cars today is hydraulic, seals need to be used to prevent fluid from leaking out. The power steering input shaft seal is designed to ensure that fluid isn’t lost from the junction point of the steering shaft and power steering system.

There are actually two seals here. The outer seal is really just a dust cover, and it’s designed to prevent dirt, dust and debris from damaging the inner seal. The inner one is the actual power steering input shaft seal. Its job is to keep fluid in the system, while preventing contaminants from entering.

Like other seals on your car, the power steering input shaft seal doesn’t really have an “active” or “inactive” state. It’s always working, because there is always fluid in the system. There is no lifespan for this seal, and it’s not part of regular maintenance service, either.

With that being said, this seal is definitely subject to wear and tear, as well as exposure to caustic power steering fluid. Over time, it will become brittle and crack, allowing fluid to seep out. A more serious leak might allow fluid to leave the system in quantities significant enough to affect your steering.

It’s important to know the signs and symptoms that indicate a possible leak from the power steering input shaft. There aren’t that many, but a few things you can watch for include the following:

  • Low power steering fluid (this indicates a leak somewhere in the system)
  • Power steering fluid under the car near the back of the engine area (where the power steering rack is located)
  • Turning the steering wheel produces a whining noise from the power steering pump (a symptom of low power steering fluid)

If you notice any of these symptoms, the entire power steering system needs to be checked, including the power steering input shaft seal. A certified mechanic can help to diagnose and replace your power steering input shaft seal if required.

This article originally appeared on YourMechanic.com as How Long Does a Power Steering Input Shaft Seal Last? and was authored by Valerie Johnston.


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