A pump will indicate when its seals have failed by leaking coolant from the weep hole at the bottom of the housing. Check for signs of moisture or mineral deposits below the shaft area on the housing. There is a coolant seal located behind the impeller within the pump. The shaft (as seen in this cutaway) is supported by a bearing assembly that is pressed into the cast housing. The fairly long structure helps support the side load from the pulley loading. Pump bearing wear is evident if there is any side play in the water pump shaft and this can lead to pump failure.