What does the strain pulley do?
A drive belt tensioner is a pulley mounted on a spring mechanism or adjustable pivot point that is used to keep tension on the engine belts. … Both are used to keeptension on the engine serpentine belts in order 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 of the pulley counterclockwise with the ratchet and socket before item belt is loose enough to remove. 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 courses 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 damage and harm to your belt-driven systems. You could have a failing tensioner pulley if you hear any squeaking or squealing under the hood. Bearings on the pulley can degrade, causing noise and heating. Pulleys are usually manufactured from either plastic or metal, so verify the pulley itself for any damage as well. At O’Reilly Auto Parts, we’ve tensioner pulleys available for many vehicle models.
The automatic pulley tensioner comes with an internal spring-loaded mechanism that keeps the serpentine belt under constant tension. Its design allows it to keep carefully the serpentine belt taut, in order that the other equipment pulleys rotate at the same rpm (revolutions each and every minute) while under the same safe pressure. Tensioner pulleys may also absorb mild shock loads that happen when the air conditioner cuts on and off. As a regularly rotating component, the pulley tensioner can give off some warning signs before failure.
Rust and Corrosion
The pulley tensioner sits subjected to the elements at the front end of the engine. Subjected to puddled water “splash-up,” with time the tensioner arm and pulley system can rust. Rust can freeze the automated tensioner device or rot the shaft bearings, that may cause a frozen posture in the adjustment pressure. Without the proper tension, the belt can slip.
Debris Contamination
Rocks, gravel and other street 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 burn 
off. Overheated pulley temp results, and finally the serpentine belt will melt and snap off.
Pulley Tensioner Spring
The pulley tensioner spring inside housing may become weak from age and repeated exposure to heat. This causes the belt to flutter and skip instead of maintaining a constant pressure on the pulley. Symptoms of a weak spring show as glazing on the lower of the serpentine belt, with an occasional flickering of the dashboard’s charging mild indicator. Squealing or squeaking will be listened to at the belt location.
Pulley Wobble
If the tensioner pulley wobbles on its shaft, it means the interior shaft bearings have worn. This will cause a pulley misalignment. Awful bearings cause an audible growling noises. The outer ends of the serpentine belt will fray and extend the belt. Eventually the rubberized belt grooves flatten out and cause major slippage. An excessively wobbling pulley can throw the belt off, creating all the add-ons to quit functioning.
Lever Arm Freeplay
Some tensioner pulleys have markings on the housing that indicate the utmost range that the pulley can travel. If the lever arm of the tensioner rides under or higher 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 up to the other accessory pulleys with a parallel alignment. Placing an extended, straightedge ruler against the face of the tensioner pulley, and 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 gives off a constant squeaking noises during engine idle. Belts that contain worn severely job a loud chirping or squealing sound. The cause points to a glazed, put on or cracked belt. Dried out or partially frozen tensioner pulley bearings could 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 will manifest itself with intermittent chirping sounds.