What does the strain pulley do?
A drive belt tensioner is a pulley mounted on a spring device or adjustable pivot point that is 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 adjust a tensioner pulley?
Turn 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 eliminate. Tighten the tensioner pulley by turning the adjustment bolt clockwise with the ratchet and socket before belt is tight.
How do I 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 can cause power damage and damage to your belt-driven devices. You may have a failing tensioner pulley if you hear any squeaking or squealing beneath the hood. Bearings on the pulley can degrade, causing noise and warmth. Pulleys are usually manufactured from either plastic or steel, so verify the pulley itself for just about any damage as well. At O’Reilly Automobile Parts, we have tensioner pulleys available 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 accessory pulleys rotate at the same rpm (revolutions per minute) while under the same safe pressure. Tensioner pulleys can also absorb gentle shock loads that happen when the air conditioning unit cuts on / off. As a regularly rotating element, the pulley tensioner can give off some indicators 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 mechanism can rust. Corrosion can freeze the computerized tensioner device or rot the shaft bearings, that may cause a frozen posture in the adjustment pressure. Without the correct pressure, the belt can slide.
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 slip on the tensioner pulley and burn up. Overheated pulley temperatures results, and eventually the serpentine belt will melt and snap off.
Pulley Tensioner Spring
The pulley tensioner spring inside housing may become weak from age 
and repeated contact with heat. This triggers the belt to flutter and skip rather than maintaining a constant strain on the pulley. Symptoms of a weak spring demonstrate as glazing on the lower of the serpentine belt, with an intermittent flickering of the dashboard’s charging lumination indicator. Squealing or squeaking will become noticed 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. Bad bearings cause 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 trigger main slippage. An excessively wobbling pulley can throw the belt off, creating all the extras 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, it indicates a stretched belt or a lever arm which has jammed in one 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 facial skin of the tensioner pulley, and then flushing it against another equipment pulley, can measure the angle. Any off-angle measurement indicates donned shaft bearings in the pulley casing.
Serpentine Belt Noise
A moderately put on serpentine belt produces a constant squeaking noise during engine idle. Belts which have worn severely job a loud chirping or squealing appear. The cause factors to a glazed, donned or cracked belt. Dry or partially frozen tensioner pulley bearings could cause such noises by deteriorating the belt prematurely.
Lever Arm Oscillation
A lever arm that repeatedly oscillates backwards and forwards 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 noises.