6 Symptoms of a Bad Timing Belt Tensioner (and Replacement Cost)

That squealing or chirping noise under the hood when you start your engine could indicate a failing timing belt tensioner. This small but critical engine part keeps the timing belt taut for proper camshaft and crankshaft synchronization.

In this article, we’ll cover common symptoms of a bad tensioner that signal replacement is needed and how much that replacement is going to cost you.

bad timing belt tensioner symptoms

Related: 5 Signs of a Bad Timing Belt

What is a Timing Belt Tensioner?

In simple terms, a timing belt tensioner is a device that maintains the proper tension on the timing belt to ensure precise timing of the camshafts and crankshaft.

Specifically, its main functions are:

  • To take up slack in the timing belt and keep it taut as components heat up and cool down. A slack belt could cause the engine to run incorrectly or stall.
  • To compensate for normal wear and stretch that occurs in the timing belt over time. Proper tension is crucial for maintaining correct valve timing.
  • To absorb shocks and isolate the timing belt from other components in the system. This helps prevent damage and extends belt life.

Timing belt tensioners work by using either a spring-loaded arm or hydraulic pressure to push against the timing belt and counteract any loosening or slackening. This keeps the belt under consistent tension to synchronize the opening and closing of the intake and exhaust valves with the piston movements.

Without an adequately functioning tensioner, valve timing could become thrown off with potentially damaging consequences.

Top 6 Bad Timing Belt Tensioner Symptoms

Here are five of the most common signs that your timing belt tensioner has failed and needs replacing. If you notice a combination of any of these, then it is likely time to replace your tensioner.

#1 – Squealing Noise

whining noise when accelerating

A squealing or chirping noise coming from the timing belt area can potentially indicate an issue with the timing belt tensioner.

As a timing belt tensioner begins to wear out and lose its ability to properly maintain tension on the timing belt, it can start making noise as the belt slaps or rubs against other components in the system. This is because the tensioner is no longer able to take up slack and absorb shocks in the belt like it should.

The noise from a bad tensioner may get louder or occur more frequently when the vehicle is first started from cold. This is due to engine components needing time to reach normal operating temperatures and expansion. At colder temperatures, there is more fluctuation in tension that the worn tensioner can no longer adequately compensate for.

Squealing or chirping sounds may also happen intermittently or only under certain loads and RPMs as the belt tension varies more without proper damping. Removing the timing belt cover can sometimes help pinpoint that the noise is radiating directly from the tensioner pulley area as well.

While a squeal or chirp alone does not always mean the tensioner needs replacing, it is certainly a warning sign that the timing system components should be inspected, especially when accompanied by other problems, to prevent potential engine damage.

Read Also: Timing Belt vs Serpentine Belt

#2 – Check Engine Light

check engine light

If the timing belt is loose because of a bad tensioner, then the timing of the valves will be off. This means problems in the engine, which will then result in the check engine light illuminating on the dashboard.

Since the check engine light alone can mean a million things, you can use scan for any trouble codes via a car scanner to confirm the issue.

#3 – Knocking Sounds

When the timing belt gets loose, it will start to knock around and hit the timing cover and the other parts inside of it. If it does not exactly sound like knocking, then it might be more of a slapping sound instead. The sound should not be confused with rod knock.

#4 – Engine Fails to Turn Over

car won't start

The camshaft and crankshaft cannot synchronize when you have a loose timing belt caused by a bad tensioner. Because of this, you won’t be able to ignite the fuel and air mixture in the chamber.

You may hear the motor after you turn the key in the ignition but you won’t be able to turn the engine over.

Related:  Causes of a Vehicle That Cranks But Won’t Start

#5 – Grinding Sounds

If the timing belt doesn’t have a firm grip on the pulleys, then it will cause the pulleys themselves to make grinding or rattling noises. This will definitely happen if the pulley bearing goes bad.

#6 – Engine Misfires

cylinder misfire causes

If the valves of the cylinder open or close too prematurely, then it will result in an engine misfire. This will happen if the timing belt is not able to rotate the camshaft and crankshaft at the same time.

Timing Belt Tensioner Replacement Cost

Best places to order parts?  See: 19 Best Online Auto Parts Stores

timing belt tensioner replacement cost

The replacement cost of the timing belt tensioner can be anywhere from $150 to $500. Parts can range from $60 to $350 depending on the vehicle and whether the tensioner is OEM or aftermarket.

Expect to pay around $90 to $150 for labor. Taxes and fees may be added to these prices.

See Also:  Timing Belt vs Timing Chain

How Long Does a Timing Belt Tensioner Last?

Unlike the timing belt itself, the tensioner doesn’t necessarily have a manufacturer’s recommended change interval. In almost all cases, the timing belt tensioner should be replaced at the same time as the timing belt which is generally between 75,000 and 100,000 miles.

The actual lifespan of the tensioner is much longer than the timing belt, but because it’s usually quite difficult to get to, you’ll save yourself a lot of money in the future if you replace the tensioner (as well as the water pump) during a timing belt replacement job.

Mark Stevens

9 Comments

    1. No, this is a timing belt. Serpentine belts don’t have teeth like a timing belt; they have ribs instead. You can see where the serpentine belt would normally sit on the crankshaft. The serpentine belt would ride on the ribbed pulley that sits just below the red pulley in the picture.

  1. My car is from timing set and it’s now overheating after few miles now and then. What can be the problem?

  2. Good advice but it’s late for me. Wish you posted this last year.

    I had this problem with my 97 honda civic. the car won’t start. I checked regular items: battery, starter, spark plug wire, distributor cap, rotor, and electrical connections etc. all in vain. i’ve never seen this problem before. After a few days of intensive research, finally i found a piece of info that says worn timing belt can cause the car not to start. my car’s timing belt is not broken, but maybe worn cause it’s running for over 80k miles. so i opened the timing cover and found the timing belt tensioner is loose, not putting pressure on the belt, timing belt is still OK.

  3. I have Audi A4T and the tensioner become so that is mean my valves are damaged cause it seems like there is no compression

    1. Defective tensioners are common with many Audi’s. Being a inteference engine that’s all it takes to destroy valves and pistons. The problem was so bad Audi issued recalls and class action lawsuits were filed. I never buy a used vehicle without a quick google search for KNOWN defects and reliability history ! Recently interested in a beautiful Nissan that looked immaculate and ran drove perfectly. Very first previous owner comment “the biggest POS i have ever owned” followed mostly bad but mixed reviews. I’ll take their word for it. Sorry to hear about the car, I know the sick disgu$ted feeling all too well.

      1. Audi built by vehicle are said by vehicle mechanics as the worst car ever. They don’t own them . They buy Toyotas

  4. My 2011 Chevy Silverado makes a ticking noise in the mornings then when it warms up it stops and I don’t hear it anymore??

    What causes this noise

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