The Chevrolet water pumps that come with your car new from the factory will last a number of years. In time the seal on the shaft for which the impeller of this pump rotates on will fail and cause coolant to leak from a hole in the bottom. This is the only reason for a water pump to be replaced on your Chevrolet engine. On older model Chevrolets, the water pump is visible in the center front of the engine. Its pulley, where the belt is attached, is just above the harmonic balancer. Most of the newer engines being produced by Chevrolet, the view of this coolant part is obstructed by other components under the hood. What has not changed is that most of the other components on the front of the engine will have to be removed or at least loosened to remove the water pump and replace it. Because the view of the Chevrolet water pump is covered up for the most part, when the seal is leaking on the shaft, it cannot be directly seen. Generally the first indication there is a problem is when the coolant level in the overflow tank is beginning to drop. There should also be a coolant puddle on the pavement just below the front middle section of your engine. On older models, the fan is connected to the water pump. If the leaking seal is ignored for too great a time, the shaft the impeller is on will begin to wobble. With the fan in close proximity to the radiator, the two could make contact making your coolant problem even worse. With the introduction of an electric fan on the front of the new engines, this is no longer a worry. The only danger is the belt becoming displaced when the seal totally fails and the pulley on the pump cannot longer function.