1993 Mercury Sable Water pump

Did you replace with a new or a re-manufactured unit? Reman unit tends to have a higher fail rate. Usually the bearing is what causing the pump to go bad. Sometimes, that unfortunately happens.

This is how your water pump looks like. Inside the water pump shaft (red rectangle) is the bearing that has gone bad. The bearing (an integral part of the water pump) connects the impeller (not seen on picture - little fins that "paddle" the water around) to the shaft (at the very top of the picture) where it is connected to the water pump pulley to be driven by the serpentine belt.