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Kate on Cars - Aug 2013 - Automotive Belt Basics


Kate on Cars - Aug 2013 - Automotive Belt Basics

by Kate Jonasse

I had originally intended to write an article on automotive belts and hoses together, because they are often spoken of together. But they are really very different, so they’ll each need their own articles.

Your car probably has at least one belt. More than likely, it has several. The two main categories of belt are accessory belts and timing belts. They operate in pretty much the same manner by connecting two or more spinning pulleys together to transfer power between them. This lets the spinning crankshaft deliver power to accessories like the alternator, power steering pump, water pump, and air-conditioning compressor, and also to the camshaft(s) through a timing belt.

Accessory belts come in a variety of shapes and styles. One of the most common types of accessory belt is the serpentine belt. A belt is considered serpentine if it is a single belt that weaves around the engine accessories like the one in the engine in this picture:

Having one automatically adjusting serpentine belt is better than having several belts that require periodic adjustment. Not only is there less maintenance with a serpentine belt, but there is less chance of having a belt break and the driver not notice it. On some older vehicles with multiple belts, the water pump belt could break and the driver wouldn’t notice until the engine overheated. If a serpentine belt breaks, it’s instantly obvious to the driver, who would instantly lose power steering and have the charging system light come on in the dash as a warning that something was wrong. It may be inconvenient to lose power steering if your serpentine belt breaks, and you’ll still want to call a tow truck. But it’s probably a lot better than having to replace your engine because you didn’t notice it was overheating until it was too late. Would you agree?

It’s important to have your belts inspected regularly, like every 3 months. A certified technician can spot a worn belt, and advise its replacement before it breaks and leaves you stranded. Serpentine belts need to be replaced anywhere from about 30,000 - 100,000 miles/3-5 years depending on what type of car you have and under what conditions it’s driven.

Another type of belt your vehicle likely has is a timing belt (although many engines have timing chains instead). A timing belt connects the engine’s crankshaft to its camshaft or camshafts. It has teeth on it to keep your engine properly timed so it can run and get you from here to there. It’s vital to have the timing belt replaced by the manufacturer’s recommended interval by mileage or by time – whichever comes first. You do not want to mess around with putting off a timing belt replacement, because if the timing belt breaks it can cause expensive engine damage, especially if your car has an interference engine. With an interference engine, if the timing belt breaks, it is likely that the pistons will hit the valves, which means the cylinder head needs to come off, potentially costing thousands of dollars and a week or more that your vehicle will need to be in the shop. This is something you can avoid by making sure you get your timing belt replaced when it’s due – anywhere from 60,000-105,000 miles, or 3-5 years depending on what type of car you have. Your shop will be able to tell you when your vehicle’s timing belt is due for replacement.

Having your vehicle’s belts inspected periodically (at least every 3 months) and replaced when necessary means your less likely to be stranded on side of the road with a broken belt. And remember, you can also ask your certified technician if you have any questions about your engine’s belts. They’ll be glad to answer your questions.