I have a 1999 Ford Explorer. The front driver's side wheel is making a whistling sound. We have replaced the brake pads and rotors recently. I suspect it may be a wheel bearing. The whistling occurs only when the car is moving and continues even when you step on the brakes.
I was told by a mechanic that you can't replace just the wheel bearing. He indicated that their is a sealed hub with a sensor and the whole mechanism must be replaced. Is this correct or can you replace just the wheel bearing?