How do you replace the water pump on a 1989 Isuzu Trooper?

To replace the water pump on a 1989 Isuzu Trooper, first disconnect the battery and drain the coolant. Remove the serpentine belt, then unbolt the water pump from the engine block, taking care to remove any old gasket material. Install the new water pump with a new gasket, reassemble the components in reverse order, refill the coolant, and reconnect the battery. Be sure to check for leaks after running the engine.