The Buick water pump's job is to pump coolant fluid through the cooling system. The Buick pump relies on a belt that is hooked up to the crankshaft of the engine. When the engine is running, the pump circulates fluid. On average, your water pump can be expected to fail sometime around 100,000 miles on your car, or sooner. Some of the reasons for failure can be traced to bad impellers, deteriorated belt or wrong tension, worn out bearings, an undersized or oversized pulley. You will notice water pump failure when the gasket (or seal) behind the water pump begins to leak, or bearing for the pulley dies. The signs of water pump failure usually begin with loud noises, such as groaning or screeching. To determine if the noise is coming from the water pump, remove its belt and turn on the engine. If the noise still persists, look elsewhere for problems in the cooling system. But if the noise is gone, it is time to replace your Buick water pump. When pumps fail, it is not worth your time to diagnose and fix the pump parts - it's easier and cheaper to replace the entire pump at once. And, while you are at it -replace the timing belt, which runs the pump. If it fails, your pump will be destroyed anyway. The labor that is required to replace your water pump is pretty close to the labor time needed to replace the timing belt, so it is smart to save time and hassle by replacing both items at the same time.