Possible Causes:
* Power Steering Pump Failure: This is the most likely culprit, especially given the whining noise. Internal pump components may have failed, leading to cavitation (air in the fluid) and loss of pressure. The whining is the pump struggling to move the aerated fluid.
* Low Fluid Level (Pre-existing but unnoticed): A low fluid level could have existed before the problem became severe. Running the pump with low fluid causes overheating and aeration, leading to the symptoms you describe. The overflow might be a result of the pump struggling and forcing fluid out.
* Leak in the System: A leak *could* be causing low fluid which in turn leads to the pump problems. Check carefully for leaks around the pump, hoses, lines, and the steering rack itself.
* Power Steering Fluid Contamination: Contamination with dirt, debris, or the wrong type of fluid can damage the pump.
* Seized or Damaged Steering Rack: A very stiff or seized steering rack can put excessive strain on the pump, leading to failure.
Before Replacing the Pump:
1. Check the Fluid Level: With the engine OFF, check the power steering fluid reservoir. If it's significantly low, that could be the primary problem. Adding the correct type and amount of fluid might resolve the issue (temporarily, at least). If the reservoir was full last night, the sudden overflow is a clue to a pump or system failure.
2. Inspect for Leaks: Carefully examine all hoses, lines, and connections for leaks. Look for wet spots, fluid drips, or signs of pressure escaping.
3. Check the Fluid: If you can access some of the old fluid, examine its color and consistency. Is it dark, discolored, or gritty? Contaminated fluid can damage the pump.
4. Try Turning the Steering Wheel: With the engine OFF, try turning the steering wheel from lock to lock. If it feels excessively stiff or binds, there may be a problem with the steering rack.
If the above checks don't reveal a simple fix, then a failing power steering pump is highly probable. Replacement is likely necessary. However, replacing the pump without addressing a potential underlying cause (like a leak) would be a waste of time and money. A professional mechanic can diagnose the root cause more accurately.
