4 Symptoms Of A Failing Drive Belt Tensioner

Here are four signs of drive belt tensioner failure:

1. Squeaky Engine Noise

Here’s what a faulty tensioner or drive belt may sound like:

• A failing belt tensioner may make a chirping or squeaking noise 
• Bad tensioner bearings will make a whining noise 
• A failing automatic tensioner may make a rattling noise
• A broken belt will make a slapping noise 

So, if you hear a worrying noise coming from your vehicle’s engine bay, you may want to have its drive belt tensioner checked out. If it’s not the tensioner, you could have a bad serpentine belt or v-belt.

Tip: Note the belt noise you hear and mention it to the mechanic when taking your vehicle for any servicing.

2. Visibly Worn Belts

On inspecting the drive belt, you may discover visible belt wear and tear. 

This may be due to:

• A bad belt tensioner 
• A defective idler pulley
• Worn-out tensioner or pulley bearings
• A misaligned pulley

This wear and tear may also appear in the form of rust or cracks on the tensioner housing or a loose tensioner arm. If ignored, tensioner housing cracks could result in belt failure or destroy parts in front of it, like the radiator.

Additionally, a worn-out belt tensioner pulley or tensioner spring won’t apply proper belt tension, making the belt lose functionality.

So, it’s best to get a belt tensioner and drive belt replacement as soon as possible.

3. Lit Warning Lights

When the drive belt loses tension, your vehicle may experience issues, like charging failure and engine overheating.

In this case, certain dashboard warning lights, like the check engine light and battery light, may turn on. The temperature gauge may also spike. 

If that happens, you might have to get the drive belt tensioner assessed at your local auto repair shop.

4. Performance Problems

A failing tensioner may lead to alternator issues or performance problems in certain elements of your car, like the water pump, power steering, and air conditioning.

These problems will also be highlighted by the lit warning lights mentioned above.

Both are a sign that your drive belt tensioner needs a replacement.

How Urgent Is A Drive Belt Tensioner Replacement?

A failed or loose tensioner can hamper the performance of your car or even leave you with a dead battery. And if the issue is left unresolved, other engine parts could be damaged, and your car’s condition may worsen.

That’s why it’s best to address tensioner and belt wear issues as soon as possible and get an entire tensioner replacement if needed.

How Much Does A Drive Belt Tensioner Replacement Cost?

A belt tensioner replacement can cost anywhere between $140 to $400, depending on the parts needed (idler pulley, bearings, etc.) and the labor costs.

Usually, labor costs around $70 to $80 when the replacement takes about an hour. However, the entire tensioner replacement can take longer for certain cars like a Nissan Maxima or Chrysler Pacifica, which may drive up the labor costs.

Moreover, the amount of damage and cost of repairs can increase when the issue is left unresolved for too long.

Tip: Do check your manufacturer’s warranty to see if it covers replacement costs.

4 FAQs On Drive Belt Tensioner Replacement

Here are answers to four queries on drive belt tensioners and their replacement:

1. What Is A Drive Belt Tensioner? Why Does It Need Replacement?

A drive belt tensioner or an idler pulley is a component in the engine bay that maintains tension on the drive belt — which could be a serpentine belt or v-belt. 

Why does the drive belt require tension?
The drive belt transfers power to various engine accessories, like the ac compressor, the power steering pump (ps pump), and the alternator (via alternator pulley). The belt tension helps the belt transfer power and stay functional by keeping it in contact with the crankshaft pulley.

However, the tensioner assembly and the drive belt can wear out over time, becoming less effective. This, in turn, can result in belt failure or reduced belt tension, which affects your car’s accessories like the alternator, and subsequently, the battery.

So, a worn-out tensioner needs to be replaced at the earliest.

Note: A vehicle may have a manual or automatic belt tensioner (spring-loaded idler pulley). It’s typically accompanied by a pulley that may also need replacement. And in most cases, a mechanic may replace an old belt as well.

2. What Are The Benefits Of Drive Belt Tensioner Replacement?

A bad v-belt or serpentine belt tensioner will reduce the performance of your car, so replacing it will mean your car will work as it should. But there are a couple of other benefits to consider, including:

• It’ll help the engine run smoothly
• It’ll keep the power steering (via ps pump) and cooling system (coolant pump, coolant radiator, etc.) functional
• It’ll prevent the engine from overheating

And as mentioned above, a bad tensioner could lead to other engine damage. So, it’s helpful to get a tensioner and an old belt replacement as soon as possible.

3. When Should You Replace The Drive Belt Tensioner?

A drive belt tensioner is designed to last the entire lifespan of a vehicle. So, you won’t need to replace it often. In fact, it’s more likely you’ll need a v-belt or serpentine belt replacement before you need a tensioner replacement.

On average, belt tensioners need a replacement once your vehicle nears the 125,000 miles mark. However, you could need a replacement as early as 50,000 miles due to unexpected wear and tear.

Typically, you’ll be able to determine whether you need a replacement if you notice a strange belt noise or any other symptoms. But you could also have it reviewed when you’re getting any automotive service, like a drive belt or timing belt replacement.

4. How To Replace A Drive Belt Tensioner: A General How-To

Whether you own a Camry, Chevrolet, or a Mazda, here’s a general idea of the steps involved in replacing a tensioner in any car:

• To remember where everything goes, take a picture of the belt routing. You can also find the routing diagram in your owner’s manual.
• Remove the engine mount retainer nuts and mounting bolt.
• Remove the engine mount to access the tensioner assembly.
• Release the belt tensioner (or tensioner pulley) with a breaker bar or ratchet and remove the old belt.
• Remove the old tensioner by unfastening the tensioner bolt (or pulley bolt). Use the right wrench size here to prevent rounding off the bolt head.
• Install the new tensioner onto the engine using the torque wrench to fasten the tensioner bolt (pulley bolt). 
• Reattach the mounting bolt.
• Install the new belt (if the old drive belt needs replacement) and tighten the new tensioner or idler pulley according to the manufacturer’s specifications. Ensure that there’s proper belt tension. 
• Reinstall the engine mount parts.
• Crank up your engine to check if the power steering, air conditioner, and other alternator-powered parts are functioning well. 

Some of these steps may be difficult to do at home without the right tools. So, it’s helpful to enlist a car repair service instead of attempting a DIY repair. Moreover, professional service can be a safer bet to ensure that your vehicle runs as it should.