What does the tension pulley do?
A travel belt tensioner is a pulley mounted on a spring system or adjustable pivot point that can be 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 many engine accessories.

How do you adjust a tensioner pulley?
Flip 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 remove. 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 while 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 in the event that you hear any squeaking or squealing beneath the hood. Bearings on the pulley can wear out, causing noise and temperature. Pulleys are usually manufactured from either plastic or metallic, so check the pulley itself for just about any damage aswell. At O’Reilly Automotive Parts, we have tensioner pulleys designed for many vehicle models.

The computerized pulley tensioner comes with an internal spring-loaded mechanism that keeps the serpentine belt under continuous tension. Its design permits it to keep carefully the serpentine belt taut, so that the other equipment pulleys rotate at the same rpm (revolutions each and every minute) while beneath the same safe pressure. Tensioner pulleys may also absorb moderate shock loads that happen when the air conditioning unit cuts on and off. As a frequently rotating component, 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. Subjected to puddled water “splash-up,” as time passes the tensioner arm and pulley device can rust. Corrosion can freeze the automated tensioner device or corrode the shaft bearings, that will cause a frozen placement in the adjustment pressure. Without the correct tension, the belt can slide.
Debris Contamination
Rocks, gravel and other road debris can 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. Overheated pulley temp 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 triggers the belt to flutter and skip instead of maintaining a constant pressure on the pulley. Symptoms of a poor spring demonstrate as glazing on the lower of the serpentine belt, with an occasional flickering of the dashboard’s charging lumination indicator. Squealing or squeaking will become read at the belt area.
Pulley Wobble
If the tensioner pulley wobbles on its shaft, it means the inside shaft bearings have worn. This may cause a pulley misalignment. Terrible bearings cause an audible growling noise. The outer ends of the serpentine belt will fray and stretch the belt. Ultimately the rubber belt grooves flatten out and trigger major slippage. An excessively wobbling pulley can toss the belt off, causing all the extras to quit functioning.
Lever Arm Freeplay
Some tensioner pulleys have markings on the housing that indicate the maximum 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 a long, straightedge ruler against the facial skin of the tensioner pulley, and then flushing it against another accessory 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 produces a constant squeaking noise during engine idle. Belts that contain worn severely job a loud chirping or squealing sound. The cause tips to a glazed, worn or cracked belt. Dried out or partially frozen tensioner pulley bearings can cause such sounds by wearing out the belt prematurely.
Lever Arm Oscillation
A lever arm that repeatedly oscillates back and forth during idle or higher 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.