What does the strain pulley do?
A travel 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 travel the many engine accessories.

How do you adapt a tensioner pulley?
Change the adjustment bolt on the side, top or bottom level of the pulley counterclockwise with the ratchet and socket until the accessory 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 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 reduction and harm to your belt-driven devices. You may have a failing tensioner pulley if you hear any squeaking or squealing under the hood. Bearings on the pulley can degrade, causing noise and heat. Pulleys are usually made of either plastic or metal, so check the pulley itself for just about any damage aswell. At O’Reilly Auto 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, in order that the other item pulleys rotate at the same rpm (revolutions each and every minute) while under the same secure pressure. Tensioner pulleys may also absorb gentle shock loads that happen when the air conditioner cuts on / off. As a regularly rotating part, the pulley tensioner can provide 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,” as time passes the tensioner arm and pulley device can rust. Corrosion can freeze the automatic tensioner device or rot the shaft bearings, that may cause a frozen placement in the adjustment pressure. Without the correct stress, the belt can slip.
Debris Contamination
Rocks, gravel and other highway debris could be thrown up into the tensioner pulley grooves and jam the mechanism. This can permit the serpentine belt to slide on the tensioner pulley and lose. 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 exposure to heat. This causes the belt to flutter and skip instead of maintaining a constant strain on the pulley. Symptoms of a fragile spring show as glazing on the lower of the serpentine belt, with an intermittent flickering of the dashboard’s charging lumination indicator. Squealing or squeaking will be heard at the belt area.
Pulley Wobble
If the tensioner pulley wobbles on its shaft, it means the interior shaft bearings have worn. This will cause a pulley misalignment. Negative bearings trigger an audible growling noises. The external ends of the serpentine belt will fray and extend the belt. At some point the rubberized belt grooves flatten out and cause key 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 casing that indicate the utmost selection 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 up to the other accessory pulleys with a parallel alignment. Placing an extended, straightedge ruler against the facial skin of the tensioner pulley, and flushing it against another item pulley, can gauge the angle. Any off-position measurement indicates worn shaft bearings in the pulley housing.
Serpentine Belt Noise
A moderately worn serpentine belt gives off 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, worn or cracked belt. Dry 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 backwards and forwards during idle or higher speeds means the the inside damper mechanism in the tensioner pulley has weakened or broken. This triggers sporadic tension strain on the belt and will manifest itself with intermittent chirping sounds.