Skip the auto shop - Our mechanics make house calls

Q: How Do Belt Tensioners Work?

asked by on

How do belt tensioners work?

The belt tensioners in your car work to ensure that there is enough tension on your serpentine belt, or other drive belts, so that everything in your engine compartment (your alternator, water pump, air conditioning compressor, etc.) operates the way it should. If the belt is too loose, it won’t drive the pulleys properly.

Belt tensioners come in two varieties; automatic and manual.

The automatic belt tensioner is a spring-loaded idler pulley that maintains constant tension on the drive belt at all engine speeds. The faster that the engine turns, the belt gets stretched more which actually makes the belt loose. The automatic tensioner keeps the belt from becoming loose when the engine speed increases.

Manual belt tensioners are idler pulleys that are tensioned by either tightening a threaded rod or a bolt. These tensioners do not maintain constant belt tension when the belt stretches, so they must be checked periodically and adjusted as needed.

If you think you’re having a problem with the belt tensioner, you will want to have the car checked as soon as possible to prevent any further damage. A technician from YourMechanic can help you service or replace your belt tensioner for you if necessary.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: My car makes a weird squeaking sound when I hit the accelerator.

We had a 2012 Forte and recently traded it for a 2016 Forte. Great cars. Squealing under hood can be caused by a few different reasons. The serpentine belt can be a common cause. The A/C compressor, water pump, alternator,...

Q: Hi im looking into a used infiniti, the owner gave me the description below, how much would all of the cost me and is it worth it?

Hello, thank you for writing in. It is nearly impossible to tell what kind of costs you are looking at with this old of a vehicle. 220,000 miles is a lot, but it sounds as if the car was maintained...

Q: Timing off in vehicle

In the interest of your safety, I would avoid driving your car. According to Chevrolet, the motor in that particular car is an interference engine. This means that, if the timing is off, the valves can make contact with the...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.