Before starting the work, refer to the warnings given. To check the water pump's operation while it's installed on the engine, there are three methods: while the engine is running at normal operating temperature, squeezing the radiator top hose should result in a pressure surge when released if the water pump is working properly; check for coolant leaks from the weep or vent holes on the water pump, which indicate a failure in the pump seal; and listen for howling sounds at the drivebelt end of the engine while it's running, which could signal water pump shaft bearing failure, and verify shaft wear by rocking the water pump pulley up and down. If the water pump is defective, it should be replaced with a new or rebuilt unit. For removal, disconnect the negative battery cable, drain the cooling system, and loosen the water pump pulley bolts (a strap wrench may be needed to hold the pulley). Remove the auxiliary drivebelt and the water pump pulley, and on SPI engines, remove the timing belt, replacing it if necessary due to coolant contamination or approaching scheduled replacement. On non-SPI engines, the water pump can be removed without removing the timing belt, except for Zetec-E engines where the timing belt must be removed to access the water pump housing bolts if replacement is needed. Disconnect the coolant hose and unbolt the timing belt idler pulley before removing the water pump mounting bolts and, if necessary, the water pump housing. Clean the pump mating surfaces carefully, replace the gasket whenever disturbed, and ensure a new O-ring and clean coolant are used for water pumps with an O-ring seal. For installation, tighten all fittings to the specified torque settings, check the timing belt for contamination, and refill the cooling system upon completion.