Q: How Do Belt Tensioners Work?

asked by on November 30, 2015

How do belt tensioners work?

Drive Belt Tensioner Replacement $134.81 - $573.33 Get a Quote

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.

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

What others are asking

How often should I change the drive belt

Hello. Your car was equipped with an EPDM-based (ethylene propylene diene monomer) serpentine belt that theoretically can last the lifetime of that vehicle. It will certainly last at least ten years or 150,000 miles, whichever comes first. Nevertheless, belts can...

Driving on freeway around 60 mph loud pop then truck died wants to turn over but dont.

answering

2004 acura mdx timing belt service: what components do you recommend replacing

Hello, thank you for writing in. When changing the timing belt, it is often recommended to change the water pump, chain tensioner, and the gaskets involved with accessing the timing chain. The price is vary greatly depending on what kind...

We have changed the fuel pump, air filter, battery, spark plugs on my nissan xtrail and the car still wont start

Hi. I'm thinking you have a broken timing belt causing the SUV not to start. If the timing belt breaks the engine jumps time and the engine has to be in time for it run. If the timing belt is...

High Pitched Squeal

From what you described, this problems sounds like it is likely due to a worn serpentine belt. You may need to have your belt replaced to get rid of the high pitched squeal. If you would like help replacing the...

serpintine belt and tensioner pulley replacement.

Hello. Thanks for writing in. Obviously you will want to clear some room to have access to the tensioner. This is easiest done by removing the radiator. Once you have the old tensioner removed, you simply reverse the process to...

Car makes cricket type sounds

If the noise is coming from the front of the engine in the drive belt area, then quite possibly one of the engine peripherals such as the alternator, power steering pump, or AC compressor is at fault. An engine...

1999 Pontiac Grand AM runs rough and smells weird

Hello. An engine running rough at idle could be a vacuum leak creating the wrong fuel ratio for the engine to operate correctly. The smell is probably unburned fuel caused by the vacuum leak issue. The belt shredding could be...

Belt squealing

This is a pretty common problem for your vehicle. Your serpentine belts are likely worn out. In addition it is highly likely that you could have a bad pulley or belt tensioner. If any one of these things are a...

Related articles

Common Signs Your Drive Belt Is Loose
The most common sign of a loose drive belt is noise, and it can range from a barely audible squeak to an...
How to Increase the Lifespan of Your Suspension
Car suspension is under constant load. Check your tire alignment, shocks and struts, and steering system to make your suspension system last longer.
Understanding the Cadillac Oil Life Monitor and Service Indicator Lights
Car symbols, or dashboard lights, are a car service reminder. The Cadillac Oil Life Monitor system indicates when and what service your car needs.