What does the strain pulley do?
A drive belt tensioner is a pulley mounted on a spring mechanism or adjustable pivot point that can be used to keep tension on the engine belts. … Both are being used to keeptension on the engine serpentine belts in order that they can drive the many engine accessories.
How do you change a tensioner pulley?
Switch the adjustment bolt privately, top or bottom level of the pulley counterclockwise with the ratchet and socket before item belt is loose enough to eliminate. Tighten the tensioner pulley by turning the adjustment bolt clockwise with the ratchet and socket until the belt is tight.
How do you know
A tensioner pulley courses the belt around the tensioner and allows the belt to spin as the tensioner maintains pressure against it. A failing tensioner pulley can cause power loss and harm to your belt-driven devices. You might have a failing tensioner pulley if you hear any squeaking or squealing under the hood. Bearings on the pulley can wear out, causing noise and high temperature. Pulleys are usually made of either plastic or metallic, so check the pulley itself for any damage aswell. At O’Reilly Vehicle Parts, we have tensioner pulleys available for many vehicle models.
The computerized pulley tensioner has an internal spring-loaded mechanism that keeps the serpentine belt under continuous tension. Its design enables it to keep the serpentine belt taut, so that the other accessory pulleys rotate at the same rpm (revolutions per minute) while under the same safe pressure. Tensioner pulleys may also absorb gentle shock loads that happen when the air conditioning unit cuts on / off. As a frequently rotating aspect, the pulley tensioner can give off some warning signs before failure.
Rust and Corrosion
The pulley tensioner sits exposed to the elements at the front of the engine. Put through puddled water “splash-up,” as time passes the tensioner arm and pulley device can rust. Rust can freeze the automatic tensioner device or corrode the shaft 
bearings, that may cause a frozen position in the adjustment pressure. Without the proper pressure, the belt can slip.
Debris Contamination
Rocks, gravel and other road debris can be thrown up in to the tensioner pulley grooves and jam the device. This can allow the serpentine belt to slip on the tensioner pulley and melt away. Overheated pulley heat results, and finally the serpentine belt will melt and snap off.
Pulley Tensioner Spring
The pulley tensioner spring inside the housing may become weak from age and repeated exposure to heat. This triggers the belt to flutter and skip instead of maintaining a constant pressure on the pulley. Symptoms of a weak spring display as glazing on the underside of the serpentine belt, with an intermittent flickering of the dashboard’s charging light indicator. Squealing or squeaking will become read 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 outer ends of the serpentine belt will fray and stretch the belt. Sooner or later the rubberized belt grooves flatten out and cause significant slippage. An excessively wobbling pulley can toss the belt off, triggering all the gadgets 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, it indicates a stretched belt or a lever arm that has jammed in one position.
Pulley Misaligment
The tensioner pulley face must match to the other accessory pulleys with a parallel alignment. Placing a long, straightedge ruler against the face of the tensioner pulley, and then flushing it against another accessory pulley, can gauge the angle. Any off-angle measurement indicates put on shaft bearings in the pulley housing.
Serpentine Belt Noise
A moderately donned serpentine belt produces a constant squeaking sound during engine idle. Belts that have worn severely task a loud chirping or squealing audio. The cause factors to a glazed, put on or cracked belt. Dried out or partially frozen tensioner pulley bearings can cause such noises by wearing out 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 can manifest itself with intermittent chirping sounds.