For many years, drive belts, V-belts, multi-vee-belts, and serpentine belts have 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 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 well, or for lengthy, if, with incorrect tension. A loose drive belt won’t drive the accessory reliably, slipping and making noise. Conversely, an excessively restricted belt may cause item or pulley bearing harm. Various types of tensioner pulley keep long-term engine and accessory quietness and reliability.
Tightening or Loosening
Sometimes, maintenance or repair will demand tightening or loosening a tensioner pulley. Replacing a drive belt or timing belt, for example, would need you to loosen a tensioner pulley to create room for the brand new belt, as the brand new belt is smaller sized compared to the worn drive belt.
You’ll need to tighten a tensioner pulley, generally, after the installing 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 need 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 groups: accessory-integrated (AI) and non-accessory-integrated (NAI). Think of AI tensioners as adjustable add-ons, 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 are the simplest, the majority of common, and least susceptible to failure. There is Car Pulley Belt certainly one caveat, however, as mechanical tensioner pulleys require manual adjustment. This makes them prone to user error, resulting in insufficient or extreme belt stress. Additionally, they have to be adjusted to compensate for belt stretch over time.