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 accessories, like the power steering pump, air-con compressor, water pump, or cooling fans. Toothed timing belts and timing chains, too, are accustomed to transmit power from the crankshaft to the camshafts, plus some from the camshaft to camshaft, based on engine design.

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

Tightening or Loosening
Sometimes, maintenance or restoration will demand tightening or loosening a tensioner pulley. Replacing a drive belt or timing belt, for instance, would need you to loosen a tensioner pulley to make room for the brand new belt, as the new belt is smaller sized compared to the worn drive belt.

You’ll need to tighten a tensioner pulley, in most cases, after the installation of a fresh drive belt, or even to adjust for a stretched drive belt that hasn’t worn enough to warrant replacement. Stretch out belts don’t require tensioner pulleys but are “stretched” into place utilizing a special tool-always use the special tool to prevent belt damage.

Tensioner pulleys generally fall into two categories: accessory-integrated (AI) and non-accessory-integrated (NAI). Think about AI tensioners as adjustable accessories, 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 susceptible to failure. There is one caveat, however, as mechanical tensioner pulleys need manual adjustment. This makes them susceptible to user error, leading to insufficient or excessive belt tension. Additionally, they have to be adjusted to pay for belt stretch over time.