A water pump that leaks even a little is on its last legs, and one that makes rumbling or screeching noises is getting close. Another sign it’s about time to replace the pump is when the engine temperature warning light comes on. Corrosion and contaminated coolant can cause seals and internal pump parts to fail. Because the water pump keeps coolant flowing through the engine, its failure can cause the engine to overheat, creating far more expensive problems than just the cost of a new pump.