The idler pulley system drives a car’s alternator and is part of a belt and pulley system that also covers power steering, the air compressor, and other devices. The pulley is essential; with all of the important equipment that it keeps moving, it would be very detrimental to the vehicle if this particular part failed. However, this pulley does deteriorate and when it does you should replace it immediately.
You should often inspect the face of the idler pulley for damage and wear and tear, and keeping it lubricated is a must as well. When the idler pulley is damaged, the movement of the belt going to the crankshaft can get jerky, which causes engine disruption and could even lead to accidents if the driver loses control of the vehicle.
Some precautions to keep in mind when buying an idler pulley:
Size: When you’re choosing a new idler pulley, keep the dimensions that you will need in mind. Manufacturers create pulleys in a wide range of sizes, so you will need to measure the width as well as the thickness of the belt drive on your vehicle. If the pulley is too wide, it can cause undue stress; while a small pulley will not power everything that needs to be powered.
Durability: Pulleys are given quite a load, and in order to handle the stress you need to look for an incredibly durable part – preferably one with flanges to add to the strength.
Quality: Some well-known brands of idler pulleys are solid, without flanges, and may be just as tough as those with flanges.
Pulley options: Keeping the belt secure on the pulley can be challenging, so some pulleys have grooves lining them to provide friction to keep the belt in place. Others have a slightly raised edge, like a guardrail, that helps keep the pulley in place.
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This article originally appeared on YourMechanic.com as How to Buy a Good Quality Idler Pulley and was authored by Valerie Johnston.