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?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. How Do Belt Tensioners Work?

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: Broken belts oil leak

This vehicle uses only one belt and an automatic tensioner. You didn't say what engine you have, but the V8 engines are known for having problems with the harmonic balancer coming loose or falling apart. This could be one reason...

Q: Has 135000 miles on original spark plugs. Car runs smooth and averages 23 mpg. It's hard for me to fix it if it ain't broke.

Spark plugs are replaced on a manufacturer specified maintenance schedule, in part due to plug gap erosion. Regular replacement at the 90,000 mile service interval interval that is specified for you model year also prevents a circumstance where the plug...

Q: Timing belt problem - 2004 Nissan Maxima

Actually yes it is normal. I will go through a few things that you may or may not have done and hopefully we can get your issue resolved. When you put your crankshaft pulley on did you use an impact?...

Related articles

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...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.