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You should always have a professional technician look at your belts and hoses as part of your regular maintenance schedule. And, to prevent premature engine wear and extend your vehicle’s life, you should do a basic belt inspection once a month.

Types of Belts

Serpentine Belts

Serpentine belts are commonly found on modern vehicles. Identifiable by their small thickness and wide surface area, a serpentine belt drives most, if not all, of your vehicle’s accessories.


V-belts get their name from their appearance. V-belts have a narrow outside surface and get thicker before tapering down. If your vehicle is equipped with V-belts, it will probably have multiple belts driving the accessories.

Timing Belts

Your timing belt cannot be seen because it is encased behind the front engine cover. The timing belt is the connection between the engine’s crankshaft and camshaft. As it rotates around the crankshaft and camshaft sprockets, proper timing is maintained. On some engines, the timing belt may also drive the water and oil pump, or a balance shaft. Some engines may have timing gears or a timing chain rather than timing belts.

Just like an alternator or air conditioning drive belt, the timing belt can fail. There is, however, one major difference. If the timing belt breaks or slips, the engine may not run and serious internal engine damage can occur. Many vehicles have clearance built into the engine components, so that if a timing belt malfunction occurs, it will not result in internal engine damage. This is called a non-interference engine. Vehicles that can have serious damage to internal engine parts due to timing belt malfunctions are called interference engines. Common problems caused by a broken or slipped timing belt on an interference engine are bent valves and piston damage. These types of repairs are costly, but can be prevented. Refer to your owner’s manual for information on timing belt care and recommended replacement intervals.

Belt Inspection

Check your vehicle’s belts with the engine off. When the engine is cold, you avoid accidental burns from a hot engine component or injuries caused by moving engine parts.

Carefully inspect the belts including edges and undersides for any signs of wear (see “Visual Signs of Wear” below). Any visible sign of wear indicates a belt may need to be replaced or a belt-driven component may be failing.

Belt tension should be checked and adjusted on a regular basis. If the belt tension is too tight, it can cause bearings in the accessory components, or the engine itself, to wear prematurely. If it is too loose, the belt will slip and squeal, causing the accessory components to work less efficiently. Inadequate tension also will cause the belt to wear excessively. The most accurate way to check tension is with a belt tension gauge, but you can estimate correct tension by pressing on the belt along its longest straight section. If the tension is correct, the belt will only have about 1/2 inch to 1 inch of play.

Drive belts are necessary to operate the accessory components attached to the engine, such as the alternator, power steering pump, air conditioner compressor, and the water pump. To fully assess the condition of the belts, do a visual inspection and test the belt tension.

Visual Signs of Wear

Glazing: The side or contact area of the belt becomes slick and shiny when a loose belt slips in the pulley. The glazed belt no longer grips adequately and the belt slips even more. Grease and oil on the pulley also can cause glazing.

Oil-soaked: Grease, oil, and other engine fluids on the belt or in the pulley grooves will glaze the belt and increase slippage. The fluid contamination also may deteriorate the belt.

Pilling: The belt’s rubber compound wears off and builds up on the drive pulleys (the wheel that is driven by or drives the belt). Lack of tension, misalignment, or worn pulleys can cause this condition.