When water pumps fail, it’s normally shaft seal failure that leaks coolant all over the driveway. Water pumps also lose effectiveness over time because impeller blades corrode. Passages can become clogged from corrosion and sometimes excessive amounts of gasket sealer that have found their way into water jackets. This hurts pumping efficiency. Always opt for a high-flow water pump in either a cast-iron stock replacement or aluminum aftermarket, as offered by Edelbrock (shown here).