* Power Steering Pump: The pump itself can fail internally, even without leaking fluid. This is a common culprit. A failing pump might make whining or groaning noises before complete failure.
* Power Steering Gearbox (Steering Gear): Internal seals within the gearbox can wear out, leading to a loss of assist even without external leaks. This often manifests as stiff steering. Internal components can also break or wear, causing failure.
* Pressure Switch: A faulty pressure switch may prevent the pump from engaging properly.
* Pressure Hose (Internal failure): While you might not see an external leak, a hose could have an internal rupture or collapse.
* Low Fluid (despite no visible leak): A very slow leak might not be immediately obvious. Fluid could be escaping in a way that's hard to see, or it could be evaporating. Always check the fluid level.
* Electrical Issues (for models with electronic assist): While less common in 1997 models, a wiring problem, sensor failure, or ECU issue could affect the power steering system in some cases.
Troubleshooting Steps:
Before replacing parts, it's crucial to troubleshoot:
1. Check the Power Steering Fluid Level: Even without a visible leak, low fluid is a possibility.
2. Listen for Noises: Whining, groaning, or squealing noises from the pump area are indicative of a problem.
3. Inspect the Belts: Ensure the power steering pump belt is properly tensioned and not damaged.
4. Check for Stiffness: How stiff is the steering? This helps pinpoint whether the problem is with the pump or the gearbox.
5. Professional Diagnosis: If you're not comfortable troubleshooting yourself, taking it to a mechanic is strongly recommended. They have the tools and experience to diagnose the problem accurately.
In summary, while a leak is a common cause of power steering failure, internal component failure is equally, if not more, likely in a 1997 GMC Sierra. A proper diagnosis is needed to determine the exact cause.
