Every car’s design includes numerous components that ensure its stable operation. One such part is the accessory belt drive, also known as the auxiliary or drive belt. Its main function is to transfer rotation from the crankshaft to various auxiliary engine components.
The accessory belt drive powers elements such as the alternator, which charges the battery, the power steering pump, the air conditioning compressor, and in some models, the water pump, provided it is not operated by the timing belt. This belt is easily recognized by its distinctive shape: it is long, flat, has longitudinal grooves on one side, and is made from reinforced rubber for added strength and durability.
There are various reasons for the failure of a service belt drive. Most often, it wears out naturally—over time, the rubber loses its elasticity and develops cracks. Incorrect tension also accelerates wear: if the belt is overtightened, it ages faster; with insufficient tension, it can slip off the pulleys, leading to overheating and damage. The condition of the bearings and pulleys also affects service life—their malfunction causes uneven operation and premature wear. Motor fluids, such as oil or antifreeze, as well as exposure to high temperatures, especially heat, negatively impact the rubber. In cold weather, cracks can lead to breakage. Installation errors can cause the part to malfunction or fail.
The replacement cost depends on the car type, the complexity of the work, and whether related components need to be changed. The belt itself usually costs between 20 and 60 euros, a set with rollers—60 to 100 euros, and labor—from 40 to 120 euros. On average, the total amount can range from 100 to 250 euros.
Scheduled replacement of the accessory belt drive is recommended every 60,000-100,000 kilometers, or every 4-6 years, depending on the manufacturer’s guidelines. However, these intervals may vary based on operating conditions, part quality, and the vehicle’s condition. Using more durable materials reduces the risk of sudden failure, which can lead to the car stalling and damage to other components such as the alternator or power steering. Regular inspections and preventive replacement at the first signs of wear help avoid serious problems.
The accessory belt drive differs from the timing belt in several aspects. It is located outside the engine and is easily accessible for inspection, while the timing belt is hidden under a protective cover. The accessory drive powers auxiliary components, whereas the timing belt synchronizes the operation of the valves and pistons. If the accessory drive fails, auxiliary systems stop working, while a timing belt failure can cause severe engine damage. The materials used also differ: the accessory belt has longitudinal grooves, while the timing belt has a toothed surface.
