Belts There are two types of engine belts. V-ribbed belt: Drives one accessory at a time. Serpentine belt: Drives the water pump, power steering pump, air conditioner compressor, alternator and fan (if it's not electric). When a Serpentine belt breaks it is the equivalent of as many as three regular V-belts breaking at the same time. Without a belt, the attached accessories do not work. Auto experts recommend changing all belts every four year, regardless of appearance. They should be inspected every 60,000 miles. If more than three cracks per inch are evident on the grooved underside of the belt, more than 80% of its service life is gone. Replacement is recommended. Hoses A car engine generates enough heat to destroy itself. The cooling system protects against damage by circulating liquid coolant that will keep the engine temperature within the correct operating range. During 4 years of field coolant tests on fleet vehicles, engineers for Gates belt manufacturer identified the primary cause of coolant failure as an electrochemical attack on the tube compound inside the hose. This phenomenon is known as ElectroChemical Degradation (ECD). A replacement interval of 4 years for all coolant carrying hoses, especially the upper radiator, by-pass and heater hoses can help prevent unexpected failure from ECD. The incidence of hose failure increases sharply after 4 years.