The idler pulley guides the drive belt, serpentine belt, or timing belt around accessories like your power steering pump, water pump, alternator, and AC compressor.
Depending on your vehicle, you have one or more of these pulleys, keeping your belts tensioned and running smoothly.
When they start to go out, you’ll see broken belts, slipping belts, and even a stopped engine.
In most cases, the average cost of replacing an idler pulley is about $150. That includes $10-$80 for the pulley itself. You’ll also pay for about an hour of labor, which ranges from $15-$200 depending on location, but averages at $60.
The table below shows a quick price comparison of idler pulley replacement cost estimates from reputable suppliers:
How Much Does Idler Pulley Replacement Cost?*
The cost of your idler pulley heavily depends on factors like the cost of labor, the vehicle you choose, and what OEM parts cost.
In addition, you might pay slightly more or less depending on what kind of pulleys you have. E.g., some pulleys require a pulley puller and others only require a socket or a hex wrench to remove.
The following chart covers the costs of replacing the idler tensioner pulley in popular vehicles.
|Vehicle||Idler Pulley Cost||Labor Cost|
*Note: Prices are estimates and were correct at the time of writing (April 2022). Cost estimates may have changed since, our figures should be used as a starting point for your own research.
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Idler Pulley Replacement Price Factors
In most cases, replacing an idler tensioner pulley will cost around $150.
However, depending on factors like the make and model of your car, the brand of the part, performance, or the number of pulleys you have, that could change.
The following price factors are very likely to influence the cost of the work.
Damage to Other Parts
It’s not uncommon to have to replace other belts when replacing a pulley. That’s because the pulley can damage the serpentine belt, cause it to slip, or even cause other issues.
E.g., if the idler pulley is not doing its job properly and the serpentine or drive belt starts to slip, the cooling might not work properly.
This could result in engine overheating and steam pressure causing leaks. Your serpentine belt may have to be replaced.
In most cases, you’ll only really have to replace the pulley and maybe the drive belt. However, if things go wrong, the AC compressor, air pump, water pump, power steering pump, and alternator might all suffer if the belt isn’t being tensioned correctly.
If you’re having issues in any of those systems after replacing the pulley, you may have more to repair.
Number of Pulleys
If you’re just replacing the idler pulley, you’ll likely have to replace one pulley.
However, some vehicles have separate idler pulleys for the AC and for the other accessories. E.g., the Corvette C6 uses an A/C Idler and an Accessory Idler.
Other vehicles might use more than two. However, that is rare.
At the same time, the idler pulley is likely to go bad at around the same time as the other pulleys. If you’re taking one off, it’s relatively simple to replace them all at once.
You might want to inspect all of your pulleys to decide if you should replace them all at once. Here, your vehicle may have anywhere from 4-12+.
So, if you end up replacing all of them, at an average of $30 each, that can end up costing quite a bit. However, it won’t add too much to labor costs, because taking off a pulley is relatively simple once you have the belt off.
Complexity of System
The more complex your system, the more you’ll spend on total repairs. For example, if your AC has its own belt, you’ll have to work around that to get the serpentine belt off.
If you have a single serpentine driving everything, you’ll have to check tension across everything when you put the belt back on.
The number of accessories on your belt will determine how long the job takes, what is likely to go wrong, and how much the total job will cost.
Make and Model of Part/Vehicle
Belt tensioners and idlers are relatively easy to buy from nearly anywhere and for nearly any brand.
Here, you can often choose universal parts, which are designed to fit most vehicles. These normally start at $15-$20 and will likely perform the same function as your original pulley – although you do want to ensure it’s a good fit.
That’s a big difference from Original Equipment Manufacture pulleys, which normally cost anywhere from $60-$120. Of course, that isn’t always true. Ford sells OEM pulleys starting from about $37.99.
But, it does mean you have options, depending on what you or your mechanic feel is a good idea.
Here, it may be important to consider the age of your vehicle, resale, or even the warranty on a non-OEM part if you’re looking at universal or made-to-fit parts.
Replacing an idler pulley will normally take less than an hour of time. Most mechanics can likely do the full job in 20 minutes or less.
However, you will have to expect to pay the minimum shop rate, which is often an hour of work. Here, you’ll pay an average of $60 + shop fees of 5-20% of the total job. So, with parts and labor, you might pay $120-$150 for the job.
Of course, you can also choose to do the job yourself. You’ll want to check if your vehicle needs a pulley puller for this, as buying one will normally cost around $20.
You might also be able to rent or borrow one if needed. However, many pulleys can also be taken off with nothing more than a socket set, so you might not have this consideration.
6 Symptoms of a Bad Idler Pulley
If your idler pulley is going bad, the first thing you’ll likely notice is noises. However, you’ll also likely see things like attached accessories not working as well, visible wear, or even broken belts.
The following 6 symptoms are good indications it’s time to check the pulley and possibly replace it.
1. Squealing or Chirping
If your belts or pulleys are squealing, chirping, or clattering, it usually means the bearings are going out. Here, the only option is to replace them.
Normally, these sounds are highest during idle or when the vehicle is starting up. If your pulleys are making noise while driving, the problem is likely very bad, and you should act quickly.
2. Accessories Stop Working
Bad pulleys can result in insufficient tensioning on the serpentine belt, meaning that accessories like the AC or the water pump stop working.
You might also get intermittent problems such as an AC that works and then doesn’t or which does not perform consistently.
If just one accessory stops working, the pulley probably isn’t the issue. But if all of them do, it is very likely to be the serpentine belt or the pulleys.
3. Visibly Worn Pulley
You can always open the hood and take a look at the pulleys on the serpentine belt. If they’re visibly worn, damaged, or cracked, they have to be replaced.
This type of inspection usually only takes a few moments and you can do it yourself. Of course, in some cases, you’ll have to move hoses out of the way or even a cover for the belts.
Either way, a quick inspection will give you a good idea if there is physical or visible damage.
4. The Pulley is Frozen
If the pulley stops, doesn’t turn at all, or is very difficult to move by hand, it’s a good sign it’s going bad.
You might have to test this by hand to see if it’s actually frozen. If it is, taking it out and replacing it with a new pulley is the only option.
5. Belts Loose or Wobbling
If your serpentine belt is loose, if it wobbles while running, or if it’s otherwise not fully attached, you might be having issues with the pully.
However, this issue might also mean your serpentine belt is poorly threaded or poorly put on.
Here, one of the biggest things to check is if the belt is installed upside down, which would mean the groove is not fitted into the belt.
6. Damaged Pulley Mount
If the pulley mount is damaged, bent, or torn, it will cause issues with the pulley.
You should always look for this while inspecting the physical pulley. However, this might not mean the actual pulley has to be replaced.
How To Replace An Idler Pulley: 8 Steps
If you want to replace an idler pulley, you can normally do so with very little extra effort. However, it’s always a good idea to look up your vehicle to determine if you need a pulley puller. If so, you can rent or buy one for relatively cheap.
However, most pulleys use a socket system, allowing you to simply remove them by unbolting the pulley nut. You can usually inspect this to check. Otherwise, specific vehicles do require special tools.
Things You’ll Need:
- Ratchet and socket set
- Flat screwdriver
- Replacement pulley
- Car’s manual
- Torque wrench
Replacing Your Idler Pulley
Replacing your idler pulley is relatively simple. However, you should always start by parking your car, turning the engine off, and taking the key out of the ignition.
Then, with the key out of the ignition, unplug the battery from the negative battery post. Tuck the cable up out of the way.
- Open your hood and check for the drive belt. There might be a protective case around it. In this case, unbolt the case and take it out.
- Check if the belt is connected to the alternator. If so, you’ll have to loosen the alternator to take the belt off. You can do so by unbolting the two bolts on the bottom bracket.
- Then check if the pulley is connected to the engine block. If so, you’ll have to loosen that bolt and slide the pulley forward.
- Loosen the tension adjustment bolt with a socket. Then, you can remove the serpentine belt.
- Unbolt the retaining bolt while holding the pulley so it doesn’t spin.
- Pull the old pulley out and compare it with the new one to make sure it fits.
- Replace the new pulley and add the center bolt. Use a torque wrench to tighten it to the specifications of your car, as found in the manual.
- Replace the parts you took off and put the serpentine belt back into place. You may want to inspect the belt first to ensure it doesn’t have to be replaced. Then, replace the case if there was one.
From there, you can reconnect the battery and test your new pulley.
If you hear a whine, if the belt brakes, or if something else goes wrong, it’s a good sign that something has gone wrong. Ideally, you should see the belt running smoothly, with no wobble and no noise.
If you still have questions, these answers should help.
Can you drive with a bad idler pulley?
It’s a bad idea to drive with a bad idler pulley because it could fail. This could cause the serpentine belt to fail.
That could result in the alternator, the water pump, and the power steering pump failing. So, driving with a bad idler pulley can cause significant damage to your vehicle.
It can also be dangerous if everything goes out while you’re driving.
How long does it take to replace idler pulley?
Normally you can replace the idler pulley in 20-30 minutes at home.
However, if you’ve never done the work before, you might want to set aside at least an hour for the work.
Is idler pulley same as tensioner?
A tensioner pulley puts tension on the inside of the belt, keeping it at an ideal pressure using a spring-loaded mounting bolt.
Idlers are used to keep the belt moving while keeping it in place – meaning they don’t usually exert pressure on the belt.
How do I test my idler pulley?
You can physically inspect your idler pulley, test if it turns, and check how the belt works. Here, the damage is most likely to happen to the sheave, the external ring.
You might also have failing bearings. In this case, the pulley is less likely to turn well or might make noise when turning.
How many miles do idler pulleys last?
Idler pulleys should normally last between 50,000 and 100,000 miles. In some cases, they can last the lifetime of the car.
If your idler pulley is failing, it usually means something is going wrong, such as a cracked sheave, bad bearings, etc., rather than normal wear and tear.
Replacing an idler pulley is a quick job and you can often do it for very cheap. If you take your car to a mechanic, it will normally cost you around $150 including parts and labor.
You can also choose to do the work yourself. However, it’s also important that you inspect the belt and the other pulleys because they are likely to fail all at once.
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