Hub Contamination
WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
If contamination (water, mud, etc.) is found in the hub cavity, look for the source. If it is due to system leaks other than the hublock, they must be found and repaired. Always install a new hublock O-ring before re-use.