A failure in the water pump can cause serious engine damage due to overheating. There are two ways to check the operation of the water pump while it's installed on the engine. If the pump is defective, it should be replaced. Water pumps have weep (or vent) holes, and if a failure occurs in the pump seal, coolant will leak from this hole. To find the hole on the water pump, you'll need a flashlight and small mirror. If the water pump shaft bearings fail, there may be a howling sound, and shaft wear can be felt if the water pump pulley is rocked up and down with the engine off. Even a pump that exhibits no outward signs of a problem can still be due for replacement. Removal for close examination is the only way to know for sure. For replacement, disconnect the negative battery cable, drain the cooling system, and if the coolant is good, save and reuse it. Remove the drivebelts, the water pump pulley, the crankshaft pulley, and timing belt covers. Detach the water pump from the engine and check the impeller for corrosion or missing fins. Clean bolt threads and engine holes, compare the new pump to the old one, and clean the engine and pump mating surfaces. Apply sealant to the new pump, set a new gasket, and attach the pump to the engine. Tighten the bolts without overtightening. Reinstall all parts, refill the cooling system, check drivebelt tension, run the engine, and check for leaks.