What does the strain pulley do?
A drive belt tensioner is a pulley mounted on a spring device or adjustable pivot point that can be used to keep tension on the engine belts. … Both are used to keeptension on the engine serpentine belts to ensure that they can travel the various engine accessories.

How do you change a tensioner pulley?
Transform the adjustment bolt on the side, top or bottom level of the pulley counterclockwise with the ratchet and socket until the equipment belt is loose enough to eliminate. Tighten the tensioner pulley by turning the adjustment bolt clockwise with the ratchet and socket before belt is tight.
How do you know

A tensioner pulley tutorials the belt around the tensioner and allows the belt to spin as the tensioner maintains pressure against it. A failing tensioner pulley could cause power loss and harm to your belt-driven systems. You may have a failing tensioner pulley if you hear any squeaking or squealing under the hood. Bearings on the pulley can degrade, causing noise and high temperature. Pulleys are usually made of either plastic or metal, so examine the pulley itself for just about any damage as well. At O’Reilly Auto Parts, we have tensioner pulleys designed for many vehicle models.

The automatic pulley tensioner has an internal spring-loaded mechanism that keeps the serpentine belt under regular tension. Its design enables it to keep the serpentine belt taut, in order that the other equipment pulleys rotate at the same rpm (revolutions each and every minute) while beneath the same secure pressure. Tensioner pulleys may also absorb slight shock loads that happen when the air conditioning unit cuts on / off. As a regularly rotating aspect, the pulley tensioner can provide off some indicators before failure.

Rust and Corrosion
The pulley tensioner sits subjected to the elements at the front of the engine. Put through puddled water “splash-up,” with time the tensioner arm and pulley mechanism can rust. Rust can freeze the computerized tensioner device or corrode the shaft bearings, which will cause a frozen job in the adjustment pressure. Without the proper tension, the belt can slide.
Debris Contamination
Rocks, gravel and other highway debris could be thrown up into the tensioner pulley grooves and jam the device. This can allow the serpentine belt to slide on the tensioner pulley and shed. Overheated pulley temp results, and finally the serpentine belt will melt and snap off.
Pulley Tensioner Spring
The pulley tensioner spring in the housing may become weak from age and repeated exposure to heat. This triggers the belt to flutter and skip rather than maintaining a constant strain on the pulley. Symptoms of a weak spring show as glazing on the lower of the serpentine belt, with an intermittent flickering of the dashboard’s charging mild indicator. Squealing or squeaking will end up being observed at the belt position.
Pulley Wobble
If the tensioner pulley wobbles on its shaft, this means the interior shaft bearings have worn. This will cause a pulley misalignment. Awful bearings trigger an audible growling noises. The external ends of the serpentine belt will fray and extend the belt. Sooner or later the rubber belt grooves flatten out and cause key slippage. An excessively wobbling pulley can toss the belt off, leading to all the accessories to quit functioning.
Lever Arm Freeplay
Some tensioner pulleys have markings on the housing that indicate the maximum range that the pulley can travel. If the lever arm of the tensioner rides under or over the designated mark, this implies a stretched belt or a lever arm that has jammed in a single position.
Pulley Misaligment
The tensioner pulley face must match to the other accessory pulleys with a parallel alignment. Placing an extended, straightedge ruler against the face of the tensioner pulley, and then flushing it against another accessory pulley, can gauge the angle. Any off-position measurement indicates donned shaft bearings in the pulley casing.
Serpentine Belt Noise
A moderately put on serpentine belt gives off a constant squeaking noise during engine idle. Belts which may have worn severely project a loud chirping or squealing sound. The cause details to a glazed, put on or cracked belt. Dry or partially frozen tensioner pulley bearings can cause such noises by deteriorating the belt prematurely.
Lever Arm Oscillation
A lever arm that repeatedly oscillates back and forth during idle or more speeds means the the within damper mechanism in the tensioner pulley has weakened or broken. This causes sporadic tension strain on the belt and will manifest itself with intermittent chirping sounds.