What does the strain pulley do?
A drive belt tensioner is a pulley mounted on a spring device or adjustable pivot point that is employed to keep tension on the engine belts. … Both are being used to keeptension on the engine serpentine belts so that they can travel the many engine accessories.
How do you change a tensioner pulley?
Convert the adjustment bolt privately, top or bottom of the pulley counterclockwise with the ratchet and socket until the accessory 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 guides 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 damage and damage to your belt-driven systems. You could have a failing tensioner pulley in the event that you hear any squeaking or squealing under the hood. Bearings on the pulley can wear out, causing noise and high temperature. Pulleys are usually manufactured from either plastic or metal, so verify the pulley itself for just about any damage as well. At O’Reilly Automotive Parts, we have tensioner pulleys designed for many vehicle models.
The programmed 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, so that the other equipment pulleys rotate at the same rpm (revolutions per minute) while beneath the same secure pressure. Tensioner pulleys can also absorb moderate shock loads that happen when the air conditioning unit cuts on / off. As a regularly rotating part, 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 system can rust. Rust can freeze the programmed tensioner device or rot the shaft bearings, that will cause a frozen situation in the adjustment pressure. Without the proper pressure, the belt can slip.
Debris Contamination
Rocks, gravel and other highway debris could be thrown up in to the tensioner pulley grooves and jam the mechanism. This can permit the serpentine belt to slide on the tensioner pulley and shed. Overheated pulley temperature 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 triggers the belt to flutter and skip instead of maintaining a constant pressure on the pulley. Symptoms of a fragile spring display 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 been told at the belt site.
Pulley Wobble
If the tensioner pulley wobbles on its shaft, this means the inside shaft bearings have worn. This may cause a pulley misalignment. Negative bearings trigger an audible growling noise. The outer ends of the serpentine belt will fray and stretch the belt. Sooner or later the rubberized belt grooves flatten out and trigger main slippage. An excessively wobbling pulley can throw the belt off, creating all the gadgets to quit functioning.
Lever Arm Freeplay
Some tensioner pulleys possess markings on the housing that indicate the maximum selection 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 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 measure the angle. Any off-position measurement indicates donned shaft bearings in the pulley housing.
Serpentine Belt Noise
A moderately donned serpentine belt produces a constant squeaking noises during engine idle. Belts that have worn severely project a loud chirping or squealing appear. The cause details to a glazed, donned or cracked belt. Dried out or partially frozen tensioner pulley bearings can cause such sounds 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 pressure on the belt and can manifest itself with intermittent chirping noises.