For decades, drive belts, V-belts, multi-vee-belts, and serpentine belts have already been used to transmit power from the engine crankshaft pulley to components, like the power steering pump, air-con compressor, water pump, or cooling fans. Toothed timing belts and timing chains, too, are used to transmit power from the crankshaft to the camshafts, and some from the camshaft to camshaft, depending on engine design.

The drive belt, timing belt, or timing chain won’t work very well, or for very long, if at all, with incorrect tension. A loose drive belt won’t drive the accessory reliably, slipping and making noise. Conversely, an excessively restricted belt may cause accessory or pulley bearing damage. Various forms of tensioner pulley keep long-term engine and item quietness and reliability.

Tightening or Loosening
Sometimes, maintenance or repair will require tightening or loosening a tensioner pulley. Replacing a drive belt or timing belt, for instance, would need you to loosen a tensioner pulley to create room for the brand new belt, as the new belt is smaller than the worn drive belt.

You will have to tighten a tensioner pulley, in most cases, after the installation of a new drive belt, or even to adapt for a stretched drive belt that hasn’t worn enough to warrant replacement. Stretch belts don’t need tensioner pulleys but are “stretched” into place using a special tool-always utilize the special tool to avoid belt damage.

Tensioner pulleys generally fall into two categories: accessory-integrated (AI) and non-accessory-integrated (NAI). Think about AI tensioners as adjustable components, such as for example an alternator, and NAI tensioners as adjustable idler pulleys. There are three types of tensioner pulleys and several methods to loosen them.
Mechanical tensioner pulleys will be the simplest, the majority of common, and least Car Pulley Belt susceptible to failure. There is one caveat, however, as mechanical tensioner pulleys need manual adjustment. This makes them prone to user error, resulting in insufficient or excessive belt pressure. Additionally, they have to be adjusted to compensate for belt stretch as time passes.