What does the strain pulley do?
A drive belt tensioner is a pulley mounted on a spring mechanism or adjustable pivot point that is employed 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 adjust a tensioner pulley?
Transform the adjustment bolt on the side, top or bottom of the pulley counterclockwise with the ratchet and socket before accessory belt is loose enough to remove. Tighten the tensioner pulley by turning the adjustment bolt clockwise with the ratchet and socket until the belt is tight.
How do I 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 reduction and harm to your belt-driven systems. You could have a failing tensioner pulley in the event that you hear any squeaking or squealing beneath the hood. Bearings on the pulley can degrade, causing noise and warmth. Pulleys are usually made of either plastic or metal, so verify the pulley itself for any damage as well. At O’Reilly Vehicle 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 frequent tension. Its design permits it to keep the serpentine belt taut, to ensure that the other item pulleys rotate at the same rpm (revolutions each and every minute) while under the same secure pressure. Tensioner pulleys can also absorb gentle shock loads that happen when the air conditioning unit cuts on / off. As a frequently rotating aspect, the pulley tensioner can provide off some warning signs before failure.
Rust and Corrosion
The pulley tensioner sits exposed to the elements at the front of the engine. Subjected to puddled water “splash-up,” with time the tensioner arm and pulley mechanism can rust. Rust can freeze the automatic tensioner device or rot the shaft bearings, which will cause a frozen job in the adjustment pressure. Without the proper pressure, the belt can slip.
Debris Contamination
Rocks, gravel and other road debris could be thrown up into the tensioner pulley grooves and jam the device. This can permit the serpentine belt to slip on the tensioner pulley and burn off. Overheated pulley temperatures results, and eventually the serpentine belt will melt and snap off.
Pulley Tensioner Spring
The pulley tensioner spring within the housing may become weak from age and repeated contact with heat. This causes 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 intermittent flickering of the dashboard’s charging mild indicator. Squealing or squeaking will be observed at the belt location.
Pulley Wobble
If the tensioner pulley wobbles on its shaft, it means the inside shaft bearings have worn. This will cause a pulley misalignment. Negative bearings cause an audible growling sound. The external ends of the serpentine belt will fray and stretch the belt. At some point the rubberized belt grooves flatten out and trigger key slippage. An excessively wobbling pulley can toss the belt off, causing all the equipment to quit functioning.
Lever Arm Freeplay
Some tensioner pulleys possess markings on the casing that indicate the utmost 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 which has jammed in one 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 flushing it against another item pulley, can measure the angle. Any off-position measurement indicates donned shaft bearings in the pulley casing.
Serpentine Belt Noise
A moderately worn serpentine belt gives off a constant squeaking sound during engine idle. Belts that have worn severely project a loud chirping or squealing sound. The cause items to a glazed, donned 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 triggers sporadic tension strain on the belt and can manifest itself with intermittent chirping sounds.