A failure in the water pump can cause serious engine damage due to overheating. The water pump is driven by the timing belt and is located beneath the timing belt cover. Water pump leaks are harder to detect with this design. Look for coolant coming out the lower timing belt cover. Water pumps are equipped with weep (or vent) holes. If a failure occurs in the pump seal, coolant will leak from the hole. With the timing belt cover removed, use a flashlight and small mirror to find the hole on the water pump from underneath to check for leaks. If there is coolant on any of the timing belt components or covers, consider this evidence of a severe leak. If the water pump shaft bearings fail, there may be a howling sound at the pump while it's running. Shaft wear can be felt with the timing belt removed if the water pump pulley is rocked up and down(with the engine off). Don't mistake drivebelt slippage, which causes a squealing sound, for water pump bearing failure. Even a pump that exhibits no outward signs of a problem, such as noise or leakage, can still be due for replacement. Removal for close examination is the only sure way to tell. Sometimes the fins on the back of the impeller can corrode to the point that cooling efficiency is hampered. If the pump is defective, replace it with a new or rebuilt unit.