A Water Pump is the part that pushes coolant around the engine so it stays at the right temperature. We bolt it to the engine block and spin its impeller with a belt. As it turns, coolant flows from the radiator into the engine and back again, carrying heat away. Made of cast iron or aluminum, it needs tight seals to prevent leaks. If the seal fails, coolant drips and the engine can boil over. We swap it out fast and refill coolant so things run cool.