Inspect the water pump for signs of contact with engine oil. Engine oil may cause the water pump gasket to swell, which may lead to a coolant leak. If water pump replacement is necessary, ensure that any engine oil is thoroughly cleaned off, prior to water pump installation. Please note that when replacing the water pump or opening the cooling system, there is a special bleed procedure that has to be performed. Vacuum bleed the cooling system for 10 minutes. Start the engine and let idle until the thermostat opens and the cooling fan runs, before driving vehicle or raising engine RPM.